STGW

SEC source: 0001104659-21-147255 · tm2134791-1_4seq1.xml · nonDerivative · entry 2

Samaha Eli · CIK 0001877589 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnote

Disclosed balance after: 5,753,210

F2 · price: The purchase price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $7.58 to $8.30, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in this footnote.

F3 · ownership.nature: These shares are held by Madison Avenue Partners, LP. The Reporting Person is the managing partner of Madison Avenue Partners, LP. The Reporting Person disclaims beneficial ownership of these securities, except to the extent of the Reporting Person's pecuniary interest therein. The filing of this statement shall not be deemed an admission that, for purposes of Section 16 of the Securities Exchange Act of 1934, as amended, or otherwise, the Reporting Person is the beneficial ownership of such securities.

SEC source: 0001104659-21-147255 · tm2134791-1_4seq1.xml · nonDerivative · entry 1

Samaha Eli · CIK 0001877589 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnote

Disclosed balance after: 5,462,914

F1 · price: The purchase price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $7.84 to $7.85, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in this footnote.

F3 · ownership.nature: These shares are held by Madison Avenue Partners, LP. The Reporting Person is the managing partner of Madison Avenue Partners, LP. The Reporting Person disclaims beneficial ownership of these securities, except to the extent of the Reporting Person's pecuniary interest therein. The filing of this statement shall not be deemed an admission that, for purposes of Section 16 of the Securities Exchange Act of 1934, as amended, or otherwise, the Reporting Person is the beneficial ownership of such securities.

SEC source: 0001104659-21-146008 · tm2134496-1_4seq1.xml · nonDerivative · entry 3

Samaha Eli · CIK 0001877589 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnote

Disclosed balance after: 5,460,249

F3 · price: The purchase price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $7.405 to $7.81, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in this footnote.

F4 · ownership.nature: These shares are held by Madison Avenue Partners, LP. The Reporting Person is the managing partner of Madison Avenue Partners, LP. The Reporting Person disclaims beneficial ownership of these securities, except to the extent of the Reporting Person's pecuniary interest therein. The filing of this statement shall not be deemed an admission that, for purposes of Section 16 of the Securities Exchange Act of 1934, as amended, or otherwise, the Reporting Person is the beneficial ownership of such securities.

SEC source: 0001104659-21-146008 · tm2134496-1_4seq1.xml · nonDerivative · entry 2

Samaha Eli · CIK 0001877589 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnote

Disclosed balance after: 5,345,249

F2 · price: The purchase price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $7.475 to $8.00, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in this footnote.

F4 · ownership.nature: These shares are held by Madison Avenue Partners, LP. The Reporting Person is the managing partner of Madison Avenue Partners, LP. The Reporting Person disclaims beneficial ownership of these securities, except to the extent of the Reporting Person's pecuniary interest therein. The filing of this statement shall not be deemed an admission that, for purposes of Section 16 of the Securities Exchange Act of 1934, as amended, or otherwise, the Reporting Person is the beneficial ownership of such securities.

SEC source: 0001104659-21-146008 · tm2134496-1_4seq1.xml · nonDerivative · entry 1

Samaha Eli · CIK 0001877589 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnote

Disclosed balance after: 5,114,849

F1 · price: The purchase price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $7.395 to $7.55, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in this footnote.

F4 · ownership.nature: These shares are held by Madison Avenue Partners, LP. The Reporting Person is the managing partner of Madison Avenue Partners, LP. The Reporting Person disclaims beneficial ownership of these securities, except to the extent of the Reporting Person's pecuniary interest therein. The filing of this statement shall not be deemed an admission that, for purposes of Section 16 of the Securities Exchange Act of 1934, as amended, or otherwise, the Reporting Person is the beneficial ownership of such securities.

SEC source: 0000895345-21-000953 · form4.xml · derivative · entry 2

Gross Bradley J. · CIK 0001447253 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See of Explanation of Responses

Disclosed balance after: 0

Underlying: Class A Common Stock · 20,948,746 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · derivative.exercise_price: On September 23, 2021, the 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Issuer (the "Series 8 Preferred Stock"), held in the aggregate by Broad Street Principal Investments, L.L.C. ("BSPI"), StoneBridge 2017, L.P., a Delaware limited partnership ("SB Employee Fund") and StoneBridge 2017 Offshore, L.P., a Cayman Islands exempted limited partnership ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds"), converted automatically into 20,948,746 shares of Class A Common Stock of the Issuer and had no expiration date.

F1 · price: On September 23, 2021, the 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Issuer (the "Series 8 Preferred Stock"), held in the aggregate by Broad Street Principal Investments, L.L.C. ("BSPI"), StoneBridge 2017, L.P., a Delaware limited partnership ("SB Employee Fund") and StoneBridge 2017 Offshore, L.P., a Cayman Islands exempted limited partnership ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds"), converted automatically into 20,948,746 shares of Class A Common Stock of the Issuer and had no expiration date.

F1 · derivative.exercise_date: On September 23, 2021, the 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Issuer (the "Series 8 Preferred Stock"), held in the aggregate by Broad Street Principal Investments, L.L.C. ("BSPI"), StoneBridge 2017, L.P., a Delaware limited partnership ("SB Employee Fund") and StoneBridge 2017 Offshore, L.P., a Cayman Islands exempted limited partnership ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds"), converted automatically into 20,948,746 shares of Class A Common Stock of the Issuer and had no expiration date.

F1 · derivative.expiration_date: On September 23, 2021, the 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Issuer (the "Series 8 Preferred Stock"), held in the aggregate by Broad Street Principal Investments, L.L.C. ("BSPI"), StoneBridge 2017, L.P., a Delaware limited partnership ("SB Employee Fund") and StoneBridge 2017 Offshore, L.P., a Cayman Islands exempted limited partnership ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds"), converted automatically into 20,948,746 shares of Class A Common Stock of the Issuer and had no expiration date.

F2 · ownership.nature: The Reporting Person is a managing director of Goldman, Sachs & Co. ("Goldman Sachs"). Goldman Sachs is a subsidiary of The Goldman Sachs Group, Inc. ("GS Group"). GS Group is the direct owner of BSPI, which directly holds 17,420,458 shares of Class A Common Stock of the Issuer following the conversion reported herein, Bridge Street Opportunity Advisors, L.L.C. ("Bridge Street") is the general partner of each of SB Employee Fund, which directly holds 923,346 shares of Class A Common Stock of the Issuer following the conversion reported herein, and SB Employee Fund Offshore, which directly holds 2,604,942 shares of Class A Common Stock of the Issuer following the conversion reported herein. Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 12,933.33 shares of Class A Common Stock of the Issuer.

F3 · ownership.nature: The Reporting Person disclaims beneficial ownership of the securities reported herein except to the extent of his pecuniary interest therein, if any.

SEC source: 0000895345-21-000953 · form4.xml · nonDerivative · entry 1

Gross Bradley J. · CIK 0001447253 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See of Explanation of Responses

Disclosed balance after: 20,961,679.33

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · price: On September 23, 2021, the 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Issuer (the "Series 8 Preferred Stock"), held in the aggregate by Broad Street Principal Investments, L.L.C. ("BSPI"), StoneBridge 2017, L.P., a Delaware limited partnership ("SB Employee Fund") and StoneBridge 2017 Offshore, L.P., a Cayman Islands exempted limited partnership ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds"), converted automatically into 20,948,746 shares of Class A Common Stock of the Issuer and had no expiration date.

F2 · ownership.nature: The Reporting Person is a managing director of Goldman, Sachs & Co. ("Goldman Sachs"). Goldman Sachs is a subsidiary of The Goldman Sachs Group, Inc. ("GS Group"). GS Group is the direct owner of BSPI, which directly holds 17,420,458 shares of Class A Common Stock of the Issuer following the conversion reported herein, Bridge Street Opportunity Advisors, L.L.C. ("Bridge Street") is the general partner of each of SB Employee Fund, which directly holds 923,346 shares of Class A Common Stock of the Issuer following the conversion reported herein, and SB Employee Fund Offshore, which directly holds 2,604,942 shares of Class A Common Stock of the Issuer following the conversion reported herein. Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 12,933.33 shares of Class A Common Stock of the Issuer.

F3 · ownership.nature: The Reporting Person disclaims beneficial ownership of the securities reported herein except to the extent of his pecuniary interest therein, if any.

SEC source: 0000895345-21-000954 · form4.xml · derivative · entry 2

GOLDMAN SACHS GROUP INC · CIK 0000886982 · 10% owner

GOLDMAN SACHS & CO. LLC · CIK 0000769993 · 10% owner

Broad Street Principal Investments, L.L.C. · CIK 0001575993 · 10% owner

StoneBridge 2017, L.P. · CIK 0001698772 · 10% owner

StoneBridge 2017 Offshore, L.P. · CIK 0001698770 · 10% owner

Bridge Street Opportunity Advisors, L.L.C. · CIK 0001615636 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See of Explanation of Responses

Disclosed balance after: 0

Underlying: Class A Common Stock · 20,948,746 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F2 · derivative.exercise_price: On September 23, 2021, the 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Issuer (the "Series 8 Preferred Stock"), held in the aggregate by BSPI, and the Employee Funds, converted automatically into 20,948,746 shares of Class A Common Stock of the Issuer and had no expiration date.

F2 · price: On September 23, 2021, the 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Issuer (the "Series 8 Preferred Stock"), held in the aggregate by BSPI, and the Employee Funds, converted automatically into 20,948,746 shares of Class A Common Stock of the Issuer and had no expiration date.

F2 · derivative.exercise_date: On September 23, 2021, the 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Issuer (the "Series 8 Preferred Stock"), held in the aggregate by BSPI, and the Employee Funds, converted automatically into 20,948,746 shares of Class A Common Stock of the Issuer and had no expiration date.

F2 · derivative.expiration_date: On September 23, 2021, the 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Issuer (the "Series 8 Preferred Stock"), held in the aggregate by BSPI, and the Employee Funds, converted automatically into 20,948,746 shares of Class A Common Stock of the Issuer and had no expiration date.

F1 · ownership.nature: This statement is being filed by The Goldman Sachs Group, Inc. ("GS Group"), Goldman, Sachs & Co. LLC ("Goldman Sachs"), Broad Street Principal Investments, L.L.C. ("BSPI"), StoneBridge 2017, L.P. ("SB Employee Fund"), StoneBridge 2017 Offshore, L.P. ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds") and Bridge Street Opportunity Advisors, L.L.C ("Bridge Street"). Goldman Sachs is a subsidiary of GS Group. Goldman Sachs is the manager of BSPI and Bridge Street and the investment manager of the Employee Funds. GS Group is the direct owner of Bridge Street. Bridge Street is the general partner of each Employee Fund.

F3 · ownership.nature: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,961,679.33 shares of Class A Common Stock, consisting of (i) 17,420,458 shares of Class A Common Stock (delivered to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 2,604,942 shares of Class A Common Stock (delivered to SB Employee Fund Offshore upon conversion of the Series 8 Preferred Stock directly held by SB Employee Fund Offshore), and (iii) 923,346 shares of Class A Common Stock (delivered to SB Employee Fund upon conversion of the Series 8 Preferred Stock directly held by SB Employee Fund) and (iv) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 12,933.33 shares of Class A Common Stock of the Issuer.

SEC source: 0000895345-21-000954 · form4.xml · nonDerivative · entry 1

GOLDMAN SACHS GROUP INC · CIK 0000886982 · 10% owner

GOLDMAN SACHS & CO. LLC · CIK 0000769993 · 10% owner

Broad Street Principal Investments, L.L.C. · CIK 0001575993 · 10% owner

StoneBridge 2017, L.P. · CIK 0001698772 · 10% owner

StoneBridge 2017 Offshore, L.P. · CIK 0001698770 · 10% owner

Bridge Street Opportunity Advisors, L.L.C. · CIK 0001615636 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See of Explanation of Responses

Disclosed balance after: 20,961,679.33

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F2 · price: On September 23, 2021, the 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Issuer (the "Series 8 Preferred Stock"), held in the aggregate by BSPI, and the Employee Funds, converted automatically into 20,948,746 shares of Class A Common Stock of the Issuer and had no expiration date.

F1 · ownership.nature: This statement is being filed by The Goldman Sachs Group, Inc. ("GS Group"), Goldman, Sachs & Co. LLC ("Goldman Sachs"), Broad Street Principal Investments, L.L.C. ("BSPI"), StoneBridge 2017, L.P. ("SB Employee Fund"), StoneBridge 2017 Offshore, L.P. ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds") and Bridge Street Opportunity Advisors, L.L.C ("Bridge Street"). Goldman Sachs is a subsidiary of GS Group. Goldman Sachs is the manager of BSPI and Bridge Street and the investment manager of the Employee Funds. GS Group is the direct owner of Bridge Street. Bridge Street is the general partner of each Employee Fund.

F3 · ownership.nature: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,961,679.33 shares of Class A Common Stock, consisting of (i) 17,420,458 shares of Class A Common Stock (delivered to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 2,604,942 shares of Class A Common Stock (delivered to SB Employee Fund Offshore upon conversion of the Series 8 Preferred Stock directly held by SB Employee Fund Offshore), and (iii) 923,346 shares of Class A Common Stock (delivered to SB Employee Fund upon conversion of the Series 8 Preferred Stock directly held by SB Employee Fund) and (iv) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 12,933.33 shares of Class A Common Stock of the Issuer.

SEC source: 0001104659-21-127740 · tm2130525d5_4.xml · nonDerivative · entry 1

Greene Ryan · CIK 0001876911 · Chief Operating Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 41,000

F1 · shares: 41,000 shares of Restricted Stock (Class A Common Stock) of the Issuer were awarded on October 15, 2021. The shares will vest on March 31, 2024, subject to achievement of financial performance targets and continued employment.

SEC source: 0001104659-21-127710 · tm2130525d4_4.xml · nonDerivative · entry 1

Leveton Jay · CIK 0001876913 · President

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 86,000

F1 · shares: 86,000 shares of Restricted Stock (Class A Common Stock) of the Issuer were awarded on October 15, 2021. The shares will vest on March 31, 2024, subject to achievement of financial performance targets and continued employment.

SEC source: 0001104659-21-127701 · tm2130525d3_4seq1.xml · nonDerivative · entry 1

Penn Mark Jeffery · CIK 0001771735 · Director · Chief Executive Officer · 10% owner

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 1,001,051

F1 · shares: 412,000 shares of Restricted Stock (Class A Common Stock) of the Issuer were awarded on October 15, 2021. The shares will vest on March 31, 2024, subject to achievement of financial performance targets and continued employment.

SEC source: 0001104659-21-127700 · tm2130525d2_4seq1.xml · nonDerivative · entry 1

DIMAGGIO VINCENZO · CIK 0001808306 · SVP, Chief Accounting Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 86,136

F1 · shares: 19,000 shares of Restricted Stock (Class A Common Stock) of the Issuer were awarded on October 15, 2021. The shares will vest on March 31, 2024, subject to achievement of financial performance targets and continued employment.

SEC source: 0001104659-21-127699 · tm2130525d1_4seq1.xml · nonDerivative · entry 1

Lanuto Frank P · CIK 0001443237 · Chief Financial Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 286,123

F1 · shares: 92,000 shares of Restricted Stock (Class A Common Stock) of the Issuer were awarded on October 15, 2021. The shares will vest on March 31, 2024, subject to achievement of financial performance targets and continued employment.

SEC source: 0001104659-21-124224 · tm2129462-2_4seq1.xml · derivative · entry 3

Penn Mark Jeffery · CIK 0001771735 · Director · Chief Executive Officer · 10% owner

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 0

Underlying: Class A Common Stock · 12,086,700 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · derivative.exercise_price: On October 7, 2021, the 50,000 shares of Series 6 Convertible Preferred Stock of the Issuer held by Stagwell Agency Holdings LLC converted automatically into 12,086,700 shares of Class A Common Stock of the Issuer and had no expiration date.

F1 · price: On October 7, 2021, the 50,000 shares of Series 6 Convertible Preferred Stock of the Issuer held by Stagwell Agency Holdings LLC converted automatically into 12,086,700 shares of Class A Common Stock of the Issuer and had no expiration date.

F1 · derivative.exercise_date: On October 7, 2021, the 50,000 shares of Series 6 Convertible Preferred Stock of the Issuer held by Stagwell Agency Holdings LLC converted automatically into 12,086,700 shares of Class A Common Stock of the Issuer and had no expiration date.

F1 · derivative.expiration_date: On October 7, 2021, the 50,000 shares of Series 6 Convertible Preferred Stock of the Issuer held by Stagwell Agency Holdings LLC converted automatically into 12,086,700 shares of Class A Common Stock of the Issuer and had no expiration date.

F2 · ownership.nature: The Reporting Person is the controlling person of The Stagwell Group LLC ("Stagwell"). Stagwell directly holds 130,000 shares of Class A Common Stock of the Issuer. Stagwell is the manager of Stagwell Agency Holdings LLC, which directly holds 26,372,414 shares of Class A Common Stock of the Issuer following the conversion reported herein. The Reporting Person disclaims beneficial ownership of the securities reported herein except to the extent of his pecuniary interest therein, if any, and this report shall not be deemed an admission that the Reporting Person is the beneficial owner of, or has any pecuniary interest in, such securities for purposes of Section 16 of the Securities Exchange Act of 1934, as amended, or for any other purpose.

SEC source: 0001104659-21-124224 · tm2129462-2_4seq1.xml · nonDerivative · entry 1

Penn Mark Jeffery · CIK 0001771735 · Director · Chief Executive Officer · 10% owner

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 26,502,414

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · price: On October 7, 2021, the 50,000 shares of Series 6 Convertible Preferred Stock of the Issuer held by Stagwell Agency Holdings LLC converted automatically into 12,086,700 shares of Class A Common Stock of the Issuer and had no expiration date.

F2 · ownership.nature: The Reporting Person is the controlling person of The Stagwell Group LLC ("Stagwell"). Stagwell directly holds 130,000 shares of Class A Common Stock of the Issuer. Stagwell is the manager of Stagwell Agency Holdings LLC, which directly holds 26,372,414 shares of Class A Common Stock of the Issuer following the conversion reported herein. The Reporting Person disclaims beneficial ownership of the securities reported herein except to the extent of his pecuniary interest therein, if any, and this report shall not be deemed an admission that the Reporting Person is the beneficial owner of, or has any pecuniary interest in, such securities for purposes of Section 16 of the Securities Exchange Act of 1934, as amended, or for any other purpose.

SEC source: 0001104659-21-108585 · tm2125721-1_4seq1.xml · nonDerivative · entry 1

Penn Mark Jeffery · CIK 0001771735 · Director · Chief Executive Officer · 10% owner

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 14,415,714

F1 · price: The purchase price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $6.62 to $6.70, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in this footnote.

F2 · ownership.nature: The shares of Class A Common Stock purchased in this transaction were purchased directly by The Stagwell Group LLC ("Stagwell"). The Reporting Person is the controlling person of Stagwell. Following this transaction, Stagwell directly holds 130,000 shares of Class A Common Stock of the Issuer. Stagwell is the manager of Stagwell Agency Holdings LLC, which directly holds 14,285,714 shares of Class A Common Stock of the Issuer. The Reporting Person disclaims beneficial ownership of the securities reported herein except to the extent of his pecuniary interest therein, if any, and this report shall not be deemed an admission that the Reporting Person is the beneficial owner of, or has any pecuniary interest in, such securities for purposes of Section 16 of the Securities Exchange Act of 1934, as amended, or for any other purpose.

SEC source: 0001104659-21-103497 · tm2124791-3_4seq1.xml · nonDerivative · entry 2

Penn Mark Jeffery · CIK 0001771735 · Director · Chief Executive Officer · 10% owner

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 589,051

F2 · balance_after: Includes 549,051 shares of unvested Restricted Stock (Class A Common Stock) of the Issuer.

SEC source: 0001104659-21-103701 · tm2124769-5_4seq1.xml · nonDerivative · entry 1

ROGERS DESIREE G · CIK 0001182862 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 97,218

F1 · shares: The reporting person was awarded shares of restricted stock (Class A Common Stock) as a component of non-employee director compensation. The shares of restricted stock will vest in full on the first anniversary of the date of grant.

SEC source: 0001104659-21-103689 · tm2124791d2_4seq1.xml · nonDerivative · entry 1

Brandt Vaughan A. · CIK 0001877331 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 78,500

F1 · shares: The reporting person was awarded shares of restricted stock (Class A Common Stock) as a component of non-employee director compensation. The shares of restricted stock will vest in full on the first anniversary of the date of grant.

SEC source: 0001104659-21-103671 · tm2124769-6_4seq1.xml · nonDerivative · entry 1

SIMON IRWIN D · CIK 0000922748 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 113,211

F1 · shares: The reporting person was awarded shares of restricted stock (Class A Common Stock) as a component of non-employee director compensation. The shares of restricted stock will vest in full on the first anniversary of the date of grant.

SEC source: 0001104659-21-103670 · tm2124769-3_4seq1.xml · nonDerivative · entry 1

Oosterman Wade · CIK 0001587270 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 83,256

F1 · shares: The reporting person was awarded restricted stock units as a component of non-employee director compensation. Each restricted stock unit represents a contingent right to receive one share of Class A Common Stock. The restricted stock units will vest in full on the first anniversary of the date of grant.

SEC source: 0001104659-21-103669 · tm2124769-1_4seq1.xml · nonDerivative · entry 1

BARSHEFSKY CHARLENE · CIK 0001145766 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 98,256

F1 · shares: The reporting person was awarded shares of restricted stock (Class A Common Stock) as a component of non-employee director compensation. The shares of restricted stock will vest in full on the first anniversary of the date of grant.

SEC source: 0001104659-21-103637 · tm2124791-5_4seq1.xml · nonDerivative · entry 1

Samaha Eli · CIK 0001877589 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 25,000

F1 · shares: The Reporting Person was awarded shares of restricted stock (Class A Common Stock) as a component of non-employee director compensation. The shares of restricted stock will vest in full on the first anniversary of the date of grant.

SEC source: 0001104659-21-103497 · tm2124791-3_4seq1.xml · nonDerivative · entry 1

Penn Mark Jeffery · CIK 0001771735 · Director · Chief Executive Officer · 10% owner

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 584,051

F1 · price: The purchase price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $5.96 to $6.02, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in this footnote.

F2 · balance_after: Includes 549,051 shares of unvested Restricted Stock (Class A Common Stock) of the Issuer.

SEC source: 0001104659-21-104073 · tm2124791d1_4seq.xml · nonDerivative · entry 1

SLATER RODNEY E · CIK 0001231982 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 25,000

F1 · shares: The reporting person was awarded shares of restricted stock (Class A Common Stock) as a component of non-employee director compensation. The shares of restricted stock will vest in full on the first anniversary of the date of grant.

SEC source: 0000895345-21-000694 · form4.xml · derivative · entry 4

Gross Bradley J. · CIK 0001447253 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnoes

Disclosed balance after: 73,849

Underlying: Class A Common Stock · 20,953,333.15 shares

Expires not disclosed

F2 · derivative.exercise_price: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F4 · derivative.exercise_price: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · derivative.exercise_price: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · derivative.exercise_price: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · derivative.exercise_price: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · derivative.exercise_price: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F2 · price: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F4 · price: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · price: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · price: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · price: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · price: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F2 · derivative.exercise_date: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F3 · derivative.exercise_date: On March 6, 2017 BSPI assigned its right to purchase 11,813 and 4,187 Preference Shares of MDC Canada to StoneBridge 2017, L.P., a Delaware limited partnership ("SB Employee Fund") and StoneBridge 2017 Offshore, L.P., a Cayman Islands exempted limited partnership ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds"), respectively, pursuant to two Assignment and Assumption Agreements. GS Group is the direct owner of BSPI and Bridge Street Opportunity Advisors, L.L.C. ("Bridge Street"). Bridge Street is the general partner of each Employee Fund.

F4 · derivative.exercise_date: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · derivative.exercise_date: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · derivative.exercise_date: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · derivative.exercise_date: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · derivative.exercise_date: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F2 · derivative.expiration_date: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F3 · derivative.expiration_date: On March 6, 2017 BSPI assigned its right to purchase 11,813 and 4,187 Preference Shares of MDC Canada to StoneBridge 2017, L.P., a Delaware limited partnership ("SB Employee Fund") and StoneBridge 2017 Offshore, L.P., a Cayman Islands exempted limited partnership ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds"), respectively, pursuant to two Assignment and Assumption Agreements. GS Group is the direct owner of BSPI and Bridge Street Opportunity Advisors, L.L.C. ("Bridge Street"). Bridge Street is the general partner of each Employee Fund.

F4 · derivative.expiration_date: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · derivative.expiration_date: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · derivative.expiration_date: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · derivative.expiration_date: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · derivative.expiration_date: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F2 · derivative.underlying_shares: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F3 · derivative.underlying_shares: On March 6, 2017 BSPI assigned its right to purchase 11,813 and 4,187 Preference Shares of MDC Canada to StoneBridge 2017, L.P., a Delaware limited partnership ("SB Employee Fund") and StoneBridge 2017 Offshore, L.P., a Cayman Islands exempted limited partnership ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds"), respectively, pursuant to two Assignment and Assumption Agreements. GS Group is the direct owner of BSPI and Bridge Street Opportunity Advisors, L.L.C. ("Bridge Street"). Bridge Street is the general partner of each Employee Fund.

F4 · derivative.underlying_shares: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · derivative.underlying_shares: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · derivative.underlying_shares: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · derivative.underlying_shares: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · derivative.underlying_shares: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F2 · balance_after: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F3 · balance_after: On March 6, 2017 BSPI assigned its right to purchase 11,813 and 4,187 Preference Shares of MDC Canada to StoneBridge 2017, L.P., a Delaware limited partnership ("SB Employee Fund") and StoneBridge 2017 Offshore, L.P., a Cayman Islands exempted limited partnership ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds"), respectively, pursuant to two Assignment and Assumption Agreements. GS Group is the direct owner of BSPI and Bridge Street Opportunity Advisors, L.L.C. ("Bridge Street"). Bridge Street is the general partner of each Employee Fund.

F4 · balance_after: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · balance_after: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · balance_after: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · balance_after: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · balance_after: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F1 · ownership.nature: The Reporting Person is a managing director of Goldman, Sachs & Co. ("Goldman Sachs"). Goldman Sachs is a subsidiary of The Goldman Sachs Group, Inc. ("GS Group"). The Reporting Person disclaims beneficial ownership of the securities reported herein except to the extent of his pecuniary interest therein, if any.

F2 · ownership.nature: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F3 · ownership.nature: On March 6, 2017 BSPI assigned its right to purchase 11,813 and 4,187 Preference Shares of MDC Canada to StoneBridge 2017, L.P., a Delaware limited partnership ("SB Employee Fund") and StoneBridge 2017 Offshore, L.P., a Cayman Islands exempted limited partnership ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds"), respectively, pursuant to two Assignment and Assumption Agreements. GS Group is the direct owner of BSPI and Bridge Street Opportunity Advisors, L.L.C. ("Bridge Street"). Bridge Street is the general partner of each Employee Fund.

F4 · ownership.nature: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · ownership.nature: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · ownership.nature: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · ownership.nature: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · ownership.nature: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

SEC source: 0000895345-21-000694 · form4.xml · derivative · entry 3

Gross Bradley J. · CIK 0001447253 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnotes

Disclosed balance after: 0

Underlying: Class A Common Stock · 20,953,333.15 shares

Expires not disclosed

F2 · derivative.exercise_price: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F4 · derivative.exercise_price: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · derivative.exercise_price: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · derivative.exercise_price: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · derivative.exercise_price: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · derivative.exercise_price: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F2 · price: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F4 · price: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · price: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · price: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · price: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · price: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F2 · derivative.exercise_date: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F3 · derivative.exercise_date: On March 6, 2017 BSPI assigned its right to purchase 11,813 and 4,187 Preference Shares of MDC Canada to StoneBridge 2017, L.P., a Delaware limited partnership ("SB Employee Fund") and StoneBridge 2017 Offshore, L.P., a Cayman Islands exempted limited partnership ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds"), respectively, pursuant to two Assignment and Assumption Agreements. GS Group is the direct owner of BSPI and Bridge Street Opportunity Advisors, L.L.C. ("Bridge Street"). Bridge Street is the general partner of each Employee Fund.

F4 · derivative.exercise_date: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · derivative.exercise_date: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · derivative.exercise_date: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · derivative.exercise_date: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · derivative.exercise_date: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F2 · derivative.expiration_date: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F3 · derivative.expiration_date: On March 6, 2017 BSPI assigned its right to purchase 11,813 and 4,187 Preference Shares of MDC Canada to StoneBridge 2017, L.P., a Delaware limited partnership ("SB Employee Fund") and StoneBridge 2017 Offshore, L.P., a Cayman Islands exempted limited partnership ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds"), respectively, pursuant to two Assignment and Assumption Agreements. GS Group is the direct owner of BSPI and Bridge Street Opportunity Advisors, L.L.C. ("Bridge Street"). Bridge Street is the general partner of each Employee Fund.

F4 · derivative.expiration_date: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · derivative.expiration_date: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · derivative.expiration_date: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · derivative.expiration_date: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · derivative.expiration_date: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F2 · derivative.underlying_shares: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F3 · derivative.underlying_shares: On March 6, 2017 BSPI assigned its right to purchase 11,813 and 4,187 Preference Shares of MDC Canada to StoneBridge 2017, L.P., a Delaware limited partnership ("SB Employee Fund") and StoneBridge 2017 Offshore, L.P., a Cayman Islands exempted limited partnership ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds"), respectively, pursuant to two Assignment and Assumption Agreements. GS Group is the direct owner of BSPI and Bridge Street Opportunity Advisors, L.L.C. ("Bridge Street"). Bridge Street is the general partner of each Employee Fund.

F4 · derivative.underlying_shares: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · derivative.underlying_shares: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · derivative.underlying_shares: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · derivative.underlying_shares: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · derivative.underlying_shares: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F2 · balance_after: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F3 · balance_after: On March 6, 2017 BSPI assigned its right to purchase 11,813 and 4,187 Preference Shares of MDC Canada to StoneBridge 2017, L.P., a Delaware limited partnership ("SB Employee Fund") and StoneBridge 2017 Offshore, L.P., a Cayman Islands exempted limited partnership ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds"), respectively, pursuant to two Assignment and Assumption Agreements. GS Group is the direct owner of BSPI and Bridge Street Opportunity Advisors, L.L.C. ("Bridge Street"). Bridge Street is the general partner of each Employee Fund.

F4 · balance_after: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · balance_after: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · balance_after: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · balance_after: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · balance_after: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F1 · ownership.nature: The Reporting Person is a managing director of Goldman, Sachs & Co. ("Goldman Sachs"). Goldman Sachs is a subsidiary of The Goldman Sachs Group, Inc. ("GS Group"). The Reporting Person disclaims beneficial ownership of the securities reported herein except to the extent of his pecuniary interest therein, if any.

F2 · ownership.nature: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F3 · ownership.nature: On March 6, 2017 BSPI assigned its right to purchase 11,813 and 4,187 Preference Shares of MDC Canada to StoneBridge 2017, L.P., a Delaware limited partnership ("SB Employee Fund") and StoneBridge 2017 Offshore, L.P., a Cayman Islands exempted limited partnership ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds"), respectively, pursuant to two Assignment and Assumption Agreements. GS Group is the direct owner of BSPI and Bridge Street Opportunity Advisors, L.L.C. ("Bridge Street"). Bridge Street is the general partner of each Employee Fund.

F4 · ownership.nature: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · ownership.nature: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · ownership.nature: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · ownership.nature: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · ownership.nature: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

SEC source: 0000895345-21-000694 · form4.xml · derivative · entry 2

Gross Bradley J. · CIK 0001447253 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnotes

Disclosed balance after: 0

Underlying: Class A Common Stock · 6,001,218.02 shares

Expires not disclosed

F2 · derivative.exercise_price: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F4 · derivative.exercise_price: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · derivative.exercise_price: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · derivative.exercise_price: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · derivative.exercise_price: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · derivative.exercise_price: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F2 · price: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F4 · price: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · price: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · price: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · price: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · price: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F2 · derivative.exercise_date: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F3 · derivative.exercise_date: On March 6, 2017 BSPI assigned its right to purchase 11,813 and 4,187 Preference Shares of MDC Canada to StoneBridge 2017, L.P., a Delaware limited partnership ("SB Employee Fund") and StoneBridge 2017 Offshore, L.P., a Cayman Islands exempted limited partnership ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds"), respectively, pursuant to two Assignment and Assumption Agreements. GS Group is the direct owner of BSPI and Bridge Street Opportunity Advisors, L.L.C. ("Bridge Street"). Bridge Street is the general partner of each Employee Fund.

F4 · derivative.exercise_date: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · derivative.exercise_date: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · derivative.exercise_date: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · derivative.exercise_date: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · derivative.exercise_date: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F2 · derivative.expiration_date: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F3 · derivative.expiration_date: On March 6, 2017 BSPI assigned its right to purchase 11,813 and 4,187 Preference Shares of MDC Canada to StoneBridge 2017, L.P., a Delaware limited partnership ("SB Employee Fund") and StoneBridge 2017 Offshore, L.P., a Cayman Islands exempted limited partnership ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds"), respectively, pursuant to two Assignment and Assumption Agreements. GS Group is the direct owner of BSPI and Bridge Street Opportunity Advisors, L.L.C. ("Bridge Street"). Bridge Street is the general partner of each Employee Fund.

F4 · derivative.expiration_date: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · derivative.expiration_date: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · derivative.expiration_date: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · derivative.expiration_date: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · derivative.expiration_date: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F2 · derivative.underlying_shares: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F3 · derivative.underlying_shares: On March 6, 2017 BSPI assigned its right to purchase 11,813 and 4,187 Preference Shares of MDC Canada to StoneBridge 2017, L.P., a Delaware limited partnership ("SB Employee Fund") and StoneBridge 2017 Offshore, L.P., a Cayman Islands exempted limited partnership ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds"), respectively, pursuant to two Assignment and Assumption Agreements. GS Group is the direct owner of BSPI and Bridge Street Opportunity Advisors, L.L.C. ("Bridge Street"). Bridge Street is the general partner of each Employee Fund.

F4 · derivative.underlying_shares: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · derivative.underlying_shares: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · derivative.underlying_shares: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · derivative.underlying_shares: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · derivative.underlying_shares: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F2 · balance_after: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F3 · balance_after: On March 6, 2017 BSPI assigned its right to purchase 11,813 and 4,187 Preference Shares of MDC Canada to StoneBridge 2017, L.P., a Delaware limited partnership ("SB Employee Fund") and StoneBridge 2017 Offshore, L.P., a Cayman Islands exempted limited partnership ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds"), respectively, pursuant to two Assignment and Assumption Agreements. GS Group is the direct owner of BSPI and Bridge Street Opportunity Advisors, L.L.C. ("Bridge Street"). Bridge Street is the general partner of each Employee Fund.

F4 · balance_after: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · balance_after: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · balance_after: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · balance_after: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · balance_after: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F1 · ownership.nature: The Reporting Person is a managing director of Goldman, Sachs & Co. ("Goldman Sachs"). Goldman Sachs is a subsidiary of The Goldman Sachs Group, Inc. ("GS Group"). The Reporting Person disclaims beneficial ownership of the securities reported herein except to the extent of his pecuniary interest therein, if any.

F2 · ownership.nature: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F3 · ownership.nature: On March 6, 2017 BSPI assigned its right to purchase 11,813 and 4,187 Preference Shares of MDC Canada to StoneBridge 2017, L.P., a Delaware limited partnership ("SB Employee Fund") and StoneBridge 2017 Offshore, L.P., a Cayman Islands exempted limited partnership ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds"), respectively, pursuant to two Assignment and Assumption Agreements. GS Group is the direct owner of BSPI and Bridge Street Opportunity Advisors, L.L.C. ("Bridge Street"). Bridge Street is the general partner of each Employee Fund.

F4 · ownership.nature: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · ownership.nature: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · ownership.nature: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · ownership.nature: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · ownership.nature: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

SEC source: 0000895345-21-000694 · form4.xml · nonDerivative · entry 1

Gross Bradley J. · CIK 0001447253 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnotes

Disclosed balance after: 20,991,737.48

F2 · shares: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F3 · shares: On March 6, 2017 BSPI assigned its right to purchase 11,813 and 4,187 Preference Shares of MDC Canada to StoneBridge 2017, L.P., a Delaware limited partnership ("SB Employee Fund") and StoneBridge 2017 Offshore, L.P., a Cayman Islands exempted limited partnership ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds"), respectively, pursuant to two Assignment and Assumption Agreements. GS Group is the direct owner of BSPI and Bridge Street Opportunity Advisors, L.L.C. ("Bridge Street"). Bridge Street is the general partner of each Employee Fund.

F4 · shares: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · shares: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · shares: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · shares: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · shares: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F2 · price: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F4 · price: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · price: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · price: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · price: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · price: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F2 · balance_after: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F3 · balance_after: On March 6, 2017 BSPI assigned its right to purchase 11,813 and 4,187 Preference Shares of MDC Canada to StoneBridge 2017, L.P., a Delaware limited partnership ("SB Employee Fund") and StoneBridge 2017 Offshore, L.P., a Cayman Islands exempted limited partnership ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds"), respectively, pursuant to two Assignment and Assumption Agreements. GS Group is the direct owner of BSPI and Bridge Street Opportunity Advisors, L.L.C. ("Bridge Street"). Bridge Street is the general partner of each Employee Fund.

F4 · balance_after: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · balance_after: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · balance_after: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · balance_after: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · balance_after: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F1 · ownership.nature: The Reporting Person is a managing director of Goldman, Sachs & Co. ("Goldman Sachs"). Goldman Sachs is a subsidiary of The Goldman Sachs Group, Inc. ("GS Group"). The Reporting Person disclaims beneficial ownership of the securities reported herein except to the extent of his pecuniary interest therein, if any.

F2 · ownership.nature: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F3 · ownership.nature: On March 6, 2017 BSPI assigned its right to purchase 11,813 and 4,187 Preference Shares of MDC Canada to StoneBridge 2017, L.P., a Delaware limited partnership ("SB Employee Fund") and StoneBridge 2017 Offshore, L.P., a Cayman Islands exempted limited partnership ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds"), respectively, pursuant to two Assignment and Assumption Agreements. GS Group is the direct owner of BSPI and Bridge Street Opportunity Advisors, L.L.C. ("Bridge Street"). Bridge Street is the general partner of each Employee Fund.

F6 · ownership.nature: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · ownership.nature: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · ownership.nature: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

SEC source: 0000895345-21-000692 · form4.xml · derivative · entry 4

GOLDMAN SACHS GROUP INC · CIK 0000886982 · 10% owner

GOLDMAN SACHS & CO. LLC · CIK 0000769993 · 10% owner

Broad Street Principal Investments, L.L.C. · CIK 0001575993 · 10% owner

StoneBridge 2017, L.P. · CIK 0001698772 · 10% owner

StoneBridge 2017 Offshore, L.P. · CIK 0001698770 · 10% owner

Bridge Street Opportunity Advisors, L.L.C. · CIK 0001615636 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footenotes

Disclosed balance after: 73,849

Underlying: Class A Common Stock · 20,953,333.15 shares

Expires not disclosed

F2 · derivative.exercise_price: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F4 · derivative.exercise_price: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · derivative.exercise_price: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · derivative.exercise_price: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · derivative.exercise_price: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · derivative.exercise_price: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F2 · price: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F4 · price: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · price: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · price: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · price: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · price: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F2 · derivative.exercise_date: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F3 · derivative.exercise_date: On March 6, 2017 BSPI assigned its right to purchase 11,813 and 4,187 Preference Shares of MDC Canada to StoneBridge 2017, L.P., a Delaware limited partnership ("SB Employee Fund") and StoneBridge 2017 Offshore, L.P., a Cayman Islands exempted limited partnership ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds"), respectively, pursuant to two Assignment and Assumption Agreements. GS Group is the direct owner of BSPI and Bridge Street Opportunity Advisors, L.L.C. ("Bridge Street"). Bridge Street is the general partner of each Employee Fund.

F4 · derivative.exercise_date: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · derivative.exercise_date: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · derivative.exercise_date: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · derivative.exercise_date: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · derivative.exercise_date: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F2 · derivative.expiration_date: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F3 · derivative.expiration_date: On March 6, 2017 BSPI assigned its right to purchase 11,813 and 4,187 Preference Shares of MDC Canada to StoneBridge 2017, L.P., a Delaware limited partnership ("SB Employee Fund") and StoneBridge 2017 Offshore, L.P., a Cayman Islands exempted limited partnership ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds"), respectively, pursuant to two Assignment and Assumption Agreements. GS Group is the direct owner of BSPI and Bridge Street Opportunity Advisors, L.L.C. ("Bridge Street"). Bridge Street is the general partner of each Employee Fund.

F4 · derivative.expiration_date: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · derivative.expiration_date: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · derivative.expiration_date: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · derivative.expiration_date: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · derivative.expiration_date: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F2 · derivative.underlying_shares: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F3 · derivative.underlying_shares: On March 6, 2017 BSPI assigned its right to purchase 11,813 and 4,187 Preference Shares of MDC Canada to StoneBridge 2017, L.P., a Delaware limited partnership ("SB Employee Fund") and StoneBridge 2017 Offshore, L.P., a Cayman Islands exempted limited partnership ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds"), respectively, pursuant to two Assignment and Assumption Agreements. GS Group is the direct owner of BSPI and Bridge Street Opportunity Advisors, L.L.C. ("Bridge Street"). Bridge Street is the general partner of each Employee Fund.

F4 · derivative.underlying_shares: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · derivative.underlying_shares: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · derivative.underlying_shares: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · derivative.underlying_shares: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · derivative.underlying_shares: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F2 · balance_after: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F3 · balance_after: On March 6, 2017 BSPI assigned its right to purchase 11,813 and 4,187 Preference Shares of MDC Canada to StoneBridge 2017, L.P., a Delaware limited partnership ("SB Employee Fund") and StoneBridge 2017 Offshore, L.P., a Cayman Islands exempted limited partnership ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds"), respectively, pursuant to two Assignment and Assumption Agreements. GS Group is the direct owner of BSPI and Bridge Street Opportunity Advisors, L.L.C. ("Bridge Street"). Bridge Street is the general partner of each Employee Fund.

F4 · balance_after: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · balance_after: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · balance_after: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · balance_after: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · balance_after: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F1 · ownership.nature: This statement is being filed by The Goldman Sachs Group, Inc. ("GS Group"), Goldman, Sachs & Co. LLC ("Goldman Sachs"), Broad Street Principal Investments, L.L.C. ("BSPI"), StoneBridge 2017, L.P. ("SB Employee Fund"), StoneBridge 2017 Offshore, L.P. ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds") and Bridge Street Opportunity Advisors, L.L.C ("Bridge Street"). Goldman Sachs is a subsidiary of GS Group. Goldman Sachs is the manager of BSPI and Bridge Street and the investment manager of the Employee Funds. GS Group is the direct owner of Bridge Street. Bridge Street is the general partner of each Employee Fund.

F2 · ownership.nature: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F3 · ownership.nature: On March 6, 2017 BSPI assigned its right to purchase 11,813 and 4,187 Preference Shares of MDC Canada to StoneBridge 2017, L.P., a Delaware limited partnership ("SB Employee Fund") and StoneBridge 2017 Offshore, L.P., a Cayman Islands exempted limited partnership ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds"), respectively, pursuant to two Assignment and Assumption Agreements. GS Group is the direct owner of BSPI and Bridge Street Opportunity Advisors, L.L.C. ("Bridge Street"). Bridge Street is the general partner of each Employee Fund.

F4 · ownership.nature: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · ownership.nature: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · ownership.nature: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · ownership.nature: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · ownership.nature: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

SEC source: 0000895345-21-000692 · form4.xml · derivative · entry 3

GOLDMAN SACHS GROUP INC · CIK 0000886982 · 10% owner

GOLDMAN SACHS & CO. LLC · CIK 0000769993 · 10% owner

Broad Street Principal Investments, L.L.C. · CIK 0001575993 · 10% owner

StoneBridge 2017, L.P. · CIK 0001698772 · 10% owner

StoneBridge 2017 Offshore, L.P. · CIK 0001698770 · 10% owner

Bridge Street Opportunity Advisors, L.L.C. · CIK 0001615636 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footenotes

Disclosed balance after: 0

Underlying: Class A Common Stock · 20,953,333.15 shares

Expires not disclosed

F2 · derivative.exercise_price: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F4 · derivative.exercise_price: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · derivative.exercise_price: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · derivative.exercise_price: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · derivative.exercise_price: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · derivative.exercise_price: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F2 · price: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F4 · price: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · price: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · price: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · price: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · price: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F2 · derivative.exercise_date: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F3 · derivative.exercise_date: On March 6, 2017 BSPI assigned its right to purchase 11,813 and 4,187 Preference Shares of MDC Canada to StoneBridge 2017, L.P., a Delaware limited partnership ("SB Employee Fund") and StoneBridge 2017 Offshore, L.P., a Cayman Islands exempted limited partnership ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds"), respectively, pursuant to two Assignment and Assumption Agreements. GS Group is the direct owner of BSPI and Bridge Street Opportunity Advisors, L.L.C. ("Bridge Street"). Bridge Street is the general partner of each Employee Fund.

F4 · derivative.exercise_date: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · derivative.exercise_date: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · derivative.exercise_date: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · derivative.exercise_date: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · derivative.exercise_date: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F2 · derivative.expiration_date: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F3 · derivative.expiration_date: On March 6, 2017 BSPI assigned its right to purchase 11,813 and 4,187 Preference Shares of MDC Canada to StoneBridge 2017, L.P., a Delaware limited partnership ("SB Employee Fund") and StoneBridge 2017 Offshore, L.P., a Cayman Islands exempted limited partnership ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds"), respectively, pursuant to two Assignment and Assumption Agreements. GS Group is the direct owner of BSPI and Bridge Street Opportunity Advisors, L.L.C. ("Bridge Street"). Bridge Street is the general partner of each Employee Fund.

F4 · derivative.expiration_date: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · derivative.expiration_date: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · derivative.expiration_date: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · derivative.expiration_date: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · derivative.expiration_date: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F2 · derivative.underlying_shares: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F3 · derivative.underlying_shares: On March 6, 2017 BSPI assigned its right to purchase 11,813 and 4,187 Preference Shares of MDC Canada to StoneBridge 2017, L.P., a Delaware limited partnership ("SB Employee Fund") and StoneBridge 2017 Offshore, L.P., a Cayman Islands exempted limited partnership ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds"), respectively, pursuant to two Assignment and Assumption Agreements. GS Group is the direct owner of BSPI and Bridge Street Opportunity Advisors, L.L.C. ("Bridge Street"). Bridge Street is the general partner of each Employee Fund.

F4 · derivative.underlying_shares: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · derivative.underlying_shares: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · derivative.underlying_shares: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · derivative.underlying_shares: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · derivative.underlying_shares: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F2 · balance_after: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F3 · balance_after: On March 6, 2017 BSPI assigned its right to purchase 11,813 and 4,187 Preference Shares of MDC Canada to StoneBridge 2017, L.P., a Delaware limited partnership ("SB Employee Fund") and StoneBridge 2017 Offshore, L.P., a Cayman Islands exempted limited partnership ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds"), respectively, pursuant to two Assignment and Assumption Agreements. GS Group is the direct owner of BSPI and Bridge Street Opportunity Advisors, L.L.C. ("Bridge Street"). Bridge Street is the general partner of each Employee Fund.

F4 · balance_after: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · balance_after: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · balance_after: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · balance_after: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · balance_after: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F1 · ownership.nature: This statement is being filed by The Goldman Sachs Group, Inc. ("GS Group"), Goldman, Sachs & Co. LLC ("Goldman Sachs"), Broad Street Principal Investments, L.L.C. ("BSPI"), StoneBridge 2017, L.P. ("SB Employee Fund"), StoneBridge 2017 Offshore, L.P. ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds") and Bridge Street Opportunity Advisors, L.L.C ("Bridge Street"). Goldman Sachs is a subsidiary of GS Group. Goldman Sachs is the manager of BSPI and Bridge Street and the investment manager of the Employee Funds. GS Group is the direct owner of Bridge Street. Bridge Street is the general partner of each Employee Fund.

F2 · ownership.nature: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F3 · ownership.nature: On March 6, 2017 BSPI assigned its right to purchase 11,813 and 4,187 Preference Shares of MDC Canada to StoneBridge 2017, L.P., a Delaware limited partnership ("SB Employee Fund") and StoneBridge 2017 Offshore, L.P., a Cayman Islands exempted limited partnership ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds"), respectively, pursuant to two Assignment and Assumption Agreements. GS Group is the direct owner of BSPI and Bridge Street Opportunity Advisors, L.L.C. ("Bridge Street"). Bridge Street is the general partner of each Employee Fund.

F4 · ownership.nature: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · ownership.nature: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · ownership.nature: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · ownership.nature: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · ownership.nature: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

SEC source: 0000895345-21-000692 · form4.xml · derivative · entry 2

GOLDMAN SACHS GROUP INC · CIK 0000886982 · 10% owner

GOLDMAN SACHS & CO. LLC · CIK 0000769993 · 10% owner

Broad Street Principal Investments, L.L.C. · CIK 0001575993 · 10% owner

StoneBridge 2017, L.P. · CIK 0001698772 · 10% owner

StoneBridge 2017 Offshore, L.P. · CIK 0001698770 · 10% owner

Bridge Street Opportunity Advisors, L.L.C. · CIK 0001615636 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footenotes

Disclosed balance after: 0

Underlying: Class A Common Stock · 6,001,218.02 shares

Expires not disclosed

F2 · derivative.exercise_price: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F4 · derivative.exercise_price: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · derivative.exercise_price: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · derivative.exercise_price: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · derivative.exercise_price: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · derivative.exercise_price: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F2 · price: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F4 · price: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · price: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · price: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · price: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · price: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F2 · derivative.exercise_date: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F3 · derivative.exercise_date: On March 6, 2017 BSPI assigned its right to purchase 11,813 and 4,187 Preference Shares of MDC Canada to StoneBridge 2017, L.P., a Delaware limited partnership ("SB Employee Fund") and StoneBridge 2017 Offshore, L.P., a Cayman Islands exempted limited partnership ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds"), respectively, pursuant to two Assignment and Assumption Agreements. GS Group is the direct owner of BSPI and Bridge Street Opportunity Advisors, L.L.C. ("Bridge Street"). Bridge Street is the general partner of each Employee Fund.

F4 · derivative.exercise_date: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · derivative.exercise_date: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · derivative.exercise_date: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · derivative.exercise_date: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · derivative.exercise_date: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F2 · derivative.expiration_date: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F3 · derivative.expiration_date: On March 6, 2017 BSPI assigned its right to purchase 11,813 and 4,187 Preference Shares of MDC Canada to StoneBridge 2017, L.P., a Delaware limited partnership ("SB Employee Fund") and StoneBridge 2017 Offshore, L.P., a Cayman Islands exempted limited partnership ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds"), respectively, pursuant to two Assignment and Assumption Agreements. GS Group is the direct owner of BSPI and Bridge Street Opportunity Advisors, L.L.C. ("Bridge Street"). Bridge Street is the general partner of each Employee Fund.

F4 · derivative.expiration_date: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · derivative.expiration_date: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · derivative.expiration_date: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · derivative.expiration_date: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · derivative.expiration_date: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F2 · derivative.underlying_shares: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F3 · derivative.underlying_shares: On March 6, 2017 BSPI assigned its right to purchase 11,813 and 4,187 Preference Shares of MDC Canada to StoneBridge 2017, L.P., a Delaware limited partnership ("SB Employee Fund") and StoneBridge 2017 Offshore, L.P., a Cayman Islands exempted limited partnership ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds"), respectively, pursuant to two Assignment and Assumption Agreements. GS Group is the direct owner of BSPI and Bridge Street Opportunity Advisors, L.L.C. ("Bridge Street"). Bridge Street is the general partner of each Employee Fund.

F4 · derivative.underlying_shares: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · derivative.underlying_shares: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · derivative.underlying_shares: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · derivative.underlying_shares: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · derivative.underlying_shares: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F2 · balance_after: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F3 · balance_after: On March 6, 2017 BSPI assigned its right to purchase 11,813 and 4,187 Preference Shares of MDC Canada to StoneBridge 2017, L.P., a Delaware limited partnership ("SB Employee Fund") and StoneBridge 2017 Offshore, L.P., a Cayman Islands exempted limited partnership ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds"), respectively, pursuant to two Assignment and Assumption Agreements. GS Group is the direct owner of BSPI and Bridge Street Opportunity Advisors, L.L.C. ("Bridge Street"). Bridge Street is the general partner of each Employee Fund.

F4 · balance_after: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · balance_after: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · balance_after: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · balance_after: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · balance_after: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F1 · ownership.nature: This statement is being filed by The Goldman Sachs Group, Inc. ("GS Group"), Goldman, Sachs & Co. LLC ("Goldman Sachs"), Broad Street Principal Investments, L.L.C. ("BSPI"), StoneBridge 2017, L.P. ("SB Employee Fund"), StoneBridge 2017 Offshore, L.P. ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds") and Bridge Street Opportunity Advisors, L.L.C ("Bridge Street"). Goldman Sachs is a subsidiary of GS Group. Goldman Sachs is the manager of BSPI and Bridge Street and the investment manager of the Employee Funds. GS Group is the direct owner of Bridge Street. Bridge Street is the general partner of each Employee Fund.

F2 · ownership.nature: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F3 · ownership.nature: On March 6, 2017 BSPI assigned its right to purchase 11,813 and 4,187 Preference Shares of MDC Canada to StoneBridge 2017, L.P., a Delaware limited partnership ("SB Employee Fund") and StoneBridge 2017 Offshore, L.P., a Cayman Islands exempted limited partnership ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds"), respectively, pursuant to two Assignment and Assumption Agreements. GS Group is the direct owner of BSPI and Bridge Street Opportunity Advisors, L.L.C. ("Bridge Street"). Bridge Street is the general partner of each Employee Fund.

F4 · ownership.nature: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · ownership.nature: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · ownership.nature: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · ownership.nature: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · ownership.nature: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

SEC source: 0000895345-21-000692 · form4.xml · nonDerivative · entry 1

GOLDMAN SACHS GROUP INC · CIK 0000886982 · 10% owner

GOLDMAN SACHS & CO. LLC · CIK 0000769993 · 10% owner

Broad Street Principal Investments, L.L.C. · CIK 0001575993 · 10% owner

StoneBridge 2017, L.P. · CIK 0001698772 · 10% owner

StoneBridge 2017 Offshore, L.P. · CIK 0001698770 · 10% owner

Bridge Street Opportunity Advisors, L.L.C. · CIK 0001615636 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnotes

Disclosed balance after: 20,991,737.48

F2 · shares: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F3 · shares: On March 6, 2017 BSPI assigned its right to purchase 11,813 and 4,187 Preference Shares of MDC Canada to StoneBridge 2017, L.P., a Delaware limited partnership ("SB Employee Fund") and StoneBridge 2017 Offshore, L.P., a Cayman Islands exempted limited partnership ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds"), respectively, pursuant to two Assignment and Assumption Agreements. GS Group is the direct owner of BSPI and Bridge Street Opportunity Advisors, L.L.C. ("Bridge Street"). Bridge Street is the general partner of each Employee Fund.

F4 · shares: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · shares: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · shares: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · shares: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · shares: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F2 · price: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F4 · price: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · price: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · price: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · price: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · price: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F2 · balance_after: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F3 · balance_after: On March 6, 2017 BSPI assigned its right to purchase 11,813 and 4,187 Preference Shares of MDC Canada to StoneBridge 2017, L.P., a Delaware limited partnership ("SB Employee Fund") and StoneBridge 2017 Offshore, L.P., a Cayman Islands exempted limited partnership ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds"), respectively, pursuant to two Assignment and Assumption Agreements. GS Group is the direct owner of BSPI and Bridge Street Opportunity Advisors, L.L.C. ("Bridge Street"). Bridge Street is the general partner of each Employee Fund.

F4 · balance_after: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · balance_after: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · balance_after: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · balance_after: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · balance_after: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F1 · ownership.nature: This statement is being filed by The Goldman Sachs Group, Inc. ("GS Group"), Goldman, Sachs & Co. LLC ("Goldman Sachs"), Broad Street Principal Investments, L.L.C. ("BSPI"), StoneBridge 2017, L.P. ("SB Employee Fund"), StoneBridge 2017 Offshore, L.P. ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds") and Bridge Street Opportunity Advisors, L.L.C ("Bridge Street"). Goldman Sachs is a subsidiary of GS Group. Goldman Sachs is the manager of BSPI and Bridge Street and the investment manager of the Employee Funds. GS Group is the direct owner of Bridge Street. Bridge Street is the general partner of each Employee Fund.

F2 · ownership.nature: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F3 · ownership.nature: On March 6, 2017 BSPI assigned its right to purchase 11,813 and 4,187 Preference Shares of MDC Canada to StoneBridge 2017, L.P., a Delaware limited partnership ("SB Employee Fund") and StoneBridge 2017 Offshore, L.P., a Cayman Islands exempted limited partnership ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds"), respectively, pursuant to two Assignment and Assumption Agreements. GS Group is the direct owner of BSPI and Bridge Street Opportunity Advisors, L.L.C. ("Bridge Street"). Bridge Street is the general partner of each Employee Fund.

F4 · ownership.nature: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · ownership.nature: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · ownership.nature: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · ownership.nature: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · ownership.nature: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

SEC source: 0000895345-21-000697 · form4.xml · derivative · entry 4

GOLDMAN SACHS GROUP INC · CIK 0000886982 · 10% owner

GOLDMAN SACHS & CO. LLC · CIK 0000769993 · 10% owner

Broad Street Principal Investments, L.L.C. · CIK 0001575993 · 10% owner

StoneBridge 2017, L.P. · CIK 0001698772 · 10% owner

StoneBridge 2017 Offshore, L.P. · CIK 0001698770 · 10% owner

Bridge Street Opportunity Advisors, L.L.C. · CIK 0001615636 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footenotes

Disclosed balance after: 73,849

Underlying: Class A Common Stock · 20,953,333.15 shares

Expires not disclosed

F2 · derivative.exercise_price: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F4 · derivative.exercise_price: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · derivative.exercise_price: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · derivative.exercise_price: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · derivative.exercise_price: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · derivative.exercise_price: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F2 · price: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F4 · price: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · price: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · price: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · price: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · price: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F2 · derivative.exercise_date: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F3 · derivative.exercise_date: On March 6, 2017 BSPI assigned its right to purchase 11,813 and 4,187 Preference Shares of MDC Canada to StoneBridge 2017, L.P., a Delaware limited partnership ("SB Employee Fund") and StoneBridge 2017 Offshore, L.P., a Cayman Islands exempted limited partnership ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds"), respectively, pursuant to two Assignment and Assumption Agreements. GS Group is the direct owner of BSPI and Bridge Street Opportunity Advisors, L.L.C. ("Bridge Street"). Bridge Street is the general partner of each Employee Fund.

F4 · derivative.exercise_date: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · derivative.exercise_date: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · derivative.exercise_date: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · derivative.exercise_date: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · derivative.exercise_date: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F2 · derivative.expiration_date: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F3 · derivative.expiration_date: On March 6, 2017 BSPI assigned its right to purchase 11,813 and 4,187 Preference Shares of MDC Canada to StoneBridge 2017, L.P., a Delaware limited partnership ("SB Employee Fund") and StoneBridge 2017 Offshore, L.P., a Cayman Islands exempted limited partnership ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds"), respectively, pursuant to two Assignment and Assumption Agreements. GS Group is the direct owner of BSPI and Bridge Street Opportunity Advisors, L.L.C. ("Bridge Street"). Bridge Street is the general partner of each Employee Fund.

F4 · derivative.expiration_date: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · derivative.expiration_date: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · derivative.expiration_date: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · derivative.expiration_date: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · derivative.expiration_date: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F2 · derivative.underlying_shares: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F3 · derivative.underlying_shares: On March 6, 2017 BSPI assigned its right to purchase 11,813 and 4,187 Preference Shares of MDC Canada to StoneBridge 2017, L.P., a Delaware limited partnership ("SB Employee Fund") and StoneBridge 2017 Offshore, L.P., a Cayman Islands exempted limited partnership ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds"), respectively, pursuant to two Assignment and Assumption Agreements. GS Group is the direct owner of BSPI and Bridge Street Opportunity Advisors, L.L.C. ("Bridge Street"). Bridge Street is the general partner of each Employee Fund.

F4 · derivative.underlying_shares: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · derivative.underlying_shares: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · derivative.underlying_shares: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · derivative.underlying_shares: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · derivative.underlying_shares: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F2 · balance_after: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F3 · balance_after: On March 6, 2017 BSPI assigned its right to purchase 11,813 and 4,187 Preference Shares of MDC Canada to StoneBridge 2017, L.P., a Delaware limited partnership ("SB Employee Fund") and StoneBridge 2017 Offshore, L.P., a Cayman Islands exempted limited partnership ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds"), respectively, pursuant to two Assignment and Assumption Agreements. GS Group is the direct owner of BSPI and Bridge Street Opportunity Advisors, L.L.C. ("Bridge Street"). Bridge Street is the general partner of each Employee Fund.

F4 · balance_after: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · balance_after: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · balance_after: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · balance_after: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · balance_after: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F1 · ownership.nature: This statement is being filed by The Goldman Sachs Group, Inc. ("GS Group"), Goldman, Sachs & Co. LLC ("Goldman Sachs"), Broad Street Principal Investments, L.L.C. ("BSPI"), StoneBridge 2017, L.P. ("SB Employee Fund"), StoneBridge 2017 Offshore, L.P. ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds") and Bridge Street Opportunity Advisors, L.L.C ("Bridge Street"). Goldman Sachs is a subsidiary of GS Group. Goldman Sachs is the manager of BSPI and Bridge Street and the investment manager of the Employee Funds. GS Group is the direct owner of Bridge Street. Bridge Street is the general partner of each Employee Fund.

F2 · ownership.nature: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F3 · ownership.nature: On March 6, 2017 BSPI assigned its right to purchase 11,813 and 4,187 Preference Shares of MDC Canada to StoneBridge 2017, L.P., a Delaware limited partnership ("SB Employee Fund") and StoneBridge 2017 Offshore, L.P., a Cayman Islands exempted limited partnership ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds"), respectively, pursuant to two Assignment and Assumption Agreements. GS Group is the direct owner of BSPI and Bridge Street Opportunity Advisors, L.L.C. ("Bridge Street"). Bridge Street is the general partner of each Employee Fund.

F4 · ownership.nature: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · ownership.nature: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · ownership.nature: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · ownership.nature: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · ownership.nature: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

SEC source: 0000895345-21-000697 · form4.xml · derivative · entry 3

GOLDMAN SACHS GROUP INC · CIK 0000886982 · 10% owner

GOLDMAN SACHS & CO. LLC · CIK 0000769993 · 10% owner

Broad Street Principal Investments, L.L.C. · CIK 0001575993 · 10% owner

StoneBridge 2017, L.P. · CIK 0001698772 · 10% owner

StoneBridge 2017 Offshore, L.P. · CIK 0001698770 · 10% owner

Bridge Street Opportunity Advisors, L.L.C. · CIK 0001615636 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footenotes

Disclosed balance after: 0

Underlying: Class A Common Stock · 20,953,333.15 shares

Expires not disclosed

F2 · derivative.exercise_price: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F4 · derivative.exercise_price: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · derivative.exercise_price: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · derivative.exercise_price: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · derivative.exercise_price: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · derivative.exercise_price: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F2 · price: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F4 · price: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · price: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · price: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · price: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · price: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F2 · derivative.exercise_date: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F3 · derivative.exercise_date: On March 6, 2017 BSPI assigned its right to purchase 11,813 and 4,187 Preference Shares of MDC Canada to StoneBridge 2017, L.P., a Delaware limited partnership ("SB Employee Fund") and StoneBridge 2017 Offshore, L.P., a Cayman Islands exempted limited partnership ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds"), respectively, pursuant to two Assignment and Assumption Agreements. GS Group is the direct owner of BSPI and Bridge Street Opportunity Advisors, L.L.C. ("Bridge Street"). Bridge Street is the general partner of each Employee Fund.

F4 · derivative.exercise_date: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · derivative.exercise_date: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · derivative.exercise_date: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · derivative.exercise_date: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · derivative.exercise_date: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F2 · derivative.expiration_date: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F3 · derivative.expiration_date: On March 6, 2017 BSPI assigned its right to purchase 11,813 and 4,187 Preference Shares of MDC Canada to StoneBridge 2017, L.P., a Delaware limited partnership ("SB Employee Fund") and StoneBridge 2017 Offshore, L.P., a Cayman Islands exempted limited partnership ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds"), respectively, pursuant to two Assignment and Assumption Agreements. GS Group is the direct owner of BSPI and Bridge Street Opportunity Advisors, L.L.C. ("Bridge Street"). Bridge Street is the general partner of each Employee Fund.

F4 · derivative.expiration_date: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · derivative.expiration_date: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · derivative.expiration_date: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · derivative.expiration_date: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · derivative.expiration_date: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F2 · derivative.underlying_shares: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F3 · derivative.underlying_shares: On March 6, 2017 BSPI assigned its right to purchase 11,813 and 4,187 Preference Shares of MDC Canada to StoneBridge 2017, L.P., a Delaware limited partnership ("SB Employee Fund") and StoneBridge 2017 Offshore, L.P., a Cayman Islands exempted limited partnership ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds"), respectively, pursuant to two Assignment and Assumption Agreements. GS Group is the direct owner of BSPI and Bridge Street Opportunity Advisors, L.L.C. ("Bridge Street"). Bridge Street is the general partner of each Employee Fund.

F4 · derivative.underlying_shares: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · derivative.underlying_shares: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · derivative.underlying_shares: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · derivative.underlying_shares: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · derivative.underlying_shares: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F2 · balance_after: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F3 · balance_after: On March 6, 2017 BSPI assigned its right to purchase 11,813 and 4,187 Preference Shares of MDC Canada to StoneBridge 2017, L.P., a Delaware limited partnership ("SB Employee Fund") and StoneBridge 2017 Offshore, L.P., a Cayman Islands exempted limited partnership ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds"), respectively, pursuant to two Assignment and Assumption Agreements. GS Group is the direct owner of BSPI and Bridge Street Opportunity Advisors, L.L.C. ("Bridge Street"). Bridge Street is the general partner of each Employee Fund.

F4 · balance_after: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · balance_after: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · balance_after: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · balance_after: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · balance_after: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F1 · ownership.nature: This statement is being filed by The Goldman Sachs Group, Inc. ("GS Group"), Goldman, Sachs & Co. LLC ("Goldman Sachs"), Broad Street Principal Investments, L.L.C. ("BSPI"), StoneBridge 2017, L.P. ("SB Employee Fund"), StoneBridge 2017 Offshore, L.P. ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds") and Bridge Street Opportunity Advisors, L.L.C ("Bridge Street"). Goldman Sachs is a subsidiary of GS Group. Goldman Sachs is the manager of BSPI and Bridge Street and the investment manager of the Employee Funds. GS Group is the direct owner of Bridge Street. Bridge Street is the general partner of each Employee Fund.

F2 · ownership.nature: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F3 · ownership.nature: On March 6, 2017 BSPI assigned its right to purchase 11,813 and 4,187 Preference Shares of MDC Canada to StoneBridge 2017, L.P., a Delaware limited partnership ("SB Employee Fund") and StoneBridge 2017 Offshore, L.P., a Cayman Islands exempted limited partnership ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds"), respectively, pursuant to two Assignment and Assumption Agreements. GS Group is the direct owner of BSPI and Bridge Street Opportunity Advisors, L.L.C. ("Bridge Street"). Bridge Street is the general partner of each Employee Fund.

F4 · ownership.nature: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · ownership.nature: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · ownership.nature: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · ownership.nature: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · ownership.nature: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

SEC source: 0000895345-21-000697 · form4.xml · derivative · entry 2

GOLDMAN SACHS GROUP INC · CIK 0000886982 · 10% owner

GOLDMAN SACHS & CO. LLC · CIK 0000769993 · 10% owner

Broad Street Principal Investments, L.L.C. · CIK 0001575993 · 10% owner

StoneBridge 2017, L.P. · CIK 0001698772 · 10% owner

StoneBridge 2017 Offshore, L.P. · CIK 0001698770 · 10% owner

Bridge Street Opportunity Advisors, L.L.C. · CIK 0001615636 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footenotes

Disclosed balance after: 0

Underlying: Class A Common Stock · 6,001,218.02 shares

Expires not disclosed

F2 · derivative.exercise_price: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F4 · derivative.exercise_price: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · derivative.exercise_price: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · derivative.exercise_price: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · derivative.exercise_price: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · derivative.exercise_price: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F2 · price: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F4 · price: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · price: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · price: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · price: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · price: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F2 · derivative.exercise_date: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F3 · derivative.exercise_date: On March 6, 2017 BSPI assigned its right to purchase 11,813 and 4,187 Preference Shares of MDC Canada to StoneBridge 2017, L.P., a Delaware limited partnership ("SB Employee Fund") and StoneBridge 2017 Offshore, L.P., a Cayman Islands exempted limited partnership ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds"), respectively, pursuant to two Assignment and Assumption Agreements. GS Group is the direct owner of BSPI and Bridge Street Opportunity Advisors, L.L.C. ("Bridge Street"). Bridge Street is the general partner of each Employee Fund.

F4 · derivative.exercise_date: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · derivative.exercise_date: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · derivative.exercise_date: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · derivative.exercise_date: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · derivative.exercise_date: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F2 · derivative.expiration_date: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F3 · derivative.expiration_date: On March 6, 2017 BSPI assigned its right to purchase 11,813 and 4,187 Preference Shares of MDC Canada to StoneBridge 2017, L.P., a Delaware limited partnership ("SB Employee Fund") and StoneBridge 2017 Offshore, L.P., a Cayman Islands exempted limited partnership ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds"), respectively, pursuant to two Assignment and Assumption Agreements. GS Group is the direct owner of BSPI and Bridge Street Opportunity Advisors, L.L.C. ("Bridge Street"). Bridge Street is the general partner of each Employee Fund.

F4 · derivative.expiration_date: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · derivative.expiration_date: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · derivative.expiration_date: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · derivative.expiration_date: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · derivative.expiration_date: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F2 · derivative.underlying_shares: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F3 · derivative.underlying_shares: On March 6, 2017 BSPI assigned its right to purchase 11,813 and 4,187 Preference Shares of MDC Canada to StoneBridge 2017, L.P., a Delaware limited partnership ("SB Employee Fund") and StoneBridge 2017 Offshore, L.P., a Cayman Islands exempted limited partnership ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds"), respectively, pursuant to two Assignment and Assumption Agreements. GS Group is the direct owner of BSPI and Bridge Street Opportunity Advisors, L.L.C. ("Bridge Street"). Bridge Street is the general partner of each Employee Fund.

F4 · derivative.underlying_shares: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · derivative.underlying_shares: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · derivative.underlying_shares: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · derivative.underlying_shares: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · derivative.underlying_shares: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F2 · balance_after: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F3 · balance_after: On March 6, 2017 BSPI assigned its right to purchase 11,813 and 4,187 Preference Shares of MDC Canada to StoneBridge 2017, L.P., a Delaware limited partnership ("SB Employee Fund") and StoneBridge 2017 Offshore, L.P., a Cayman Islands exempted limited partnership ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds"), respectively, pursuant to two Assignment and Assumption Agreements. GS Group is the direct owner of BSPI and Bridge Street Opportunity Advisors, L.L.C. ("Bridge Street"). Bridge Street is the general partner of each Employee Fund.

F4 · balance_after: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · balance_after: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · balance_after: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · balance_after: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · balance_after: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F1 · ownership.nature: This statement is being filed by The Goldman Sachs Group, Inc. ("GS Group"), Goldman, Sachs & Co. LLC ("Goldman Sachs"), Broad Street Principal Investments, L.L.C. ("BSPI"), StoneBridge 2017, L.P. ("SB Employee Fund"), StoneBridge 2017 Offshore, L.P. ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds") and Bridge Street Opportunity Advisors, L.L.C ("Bridge Street"). Goldman Sachs is a subsidiary of GS Group. Goldman Sachs is the manager of BSPI and Bridge Street and the investment manager of the Employee Funds. GS Group is the direct owner of Bridge Street. Bridge Street is the general partner of each Employee Fund.

F2 · ownership.nature: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F3 · ownership.nature: On March 6, 2017 BSPI assigned its right to purchase 11,813 and 4,187 Preference Shares of MDC Canada to StoneBridge 2017, L.P., a Delaware limited partnership ("SB Employee Fund") and StoneBridge 2017 Offshore, L.P., a Cayman Islands exempted limited partnership ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds"), respectively, pursuant to two Assignment and Assumption Agreements. GS Group is the direct owner of BSPI and Bridge Street Opportunity Advisors, L.L.C. ("Bridge Street"). Bridge Street is the general partner of each Employee Fund.

F4 · ownership.nature: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · ownership.nature: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · ownership.nature: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · ownership.nature: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · ownership.nature: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

SEC source: 0000895345-21-000697 · form4.xml · nonDerivative · entry 1

GOLDMAN SACHS GROUP INC · CIK 0000886982 · 10% owner

GOLDMAN SACHS & CO. LLC · CIK 0000769993 · 10% owner

Broad Street Principal Investments, L.L.C. · CIK 0001575993 · 10% owner

StoneBridge 2017, L.P. · CIK 0001698772 · 10% owner

StoneBridge 2017 Offshore, L.P. · CIK 0001698770 · 10% owner

Bridge Street Opportunity Advisors, L.L.C. · CIK 0001615636 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnotes

Disclosed balance after: 20,991,737.48

F2 · shares: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F3 · shares: On March 6, 2017 BSPI assigned its right to purchase 11,813 and 4,187 Preference Shares of MDC Canada to StoneBridge 2017, L.P., a Delaware limited partnership ("SB Employee Fund") and StoneBridge 2017 Offshore, L.P., a Cayman Islands exempted limited partnership ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds"), respectively, pursuant to two Assignment and Assumption Agreements. GS Group is the direct owner of BSPI and Bridge Street Opportunity Advisors, L.L.C. ("Bridge Street"). Bridge Street is the general partner of each Employee Fund.

F4 · shares: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · shares: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · shares: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · shares: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · shares: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F2 · price: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F4 · price: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · price: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · price: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · price: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · price: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F2 · balance_after: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F3 · balance_after: On March 6, 2017 BSPI assigned its right to purchase 11,813 and 4,187 Preference Shares of MDC Canada to StoneBridge 2017, L.P., a Delaware limited partnership ("SB Employee Fund") and StoneBridge 2017 Offshore, L.P., a Cayman Islands exempted limited partnership ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds"), respectively, pursuant to two Assignment and Assumption Agreements. GS Group is the direct owner of BSPI and Bridge Street Opportunity Advisors, L.L.C. ("Bridge Street"). Bridge Street is the general partner of each Employee Fund.

F4 · balance_after: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · balance_after: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · balance_after: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · balance_after: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · balance_after: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

F1 · ownership.nature: This statement is being filed by The Goldman Sachs Group, Inc. ("GS Group"), Goldman, Sachs & Co. LLC ("Goldman Sachs"), Broad Street Principal Investments, L.L.C. ("BSPI"), StoneBridge 2017, L.P. ("SB Employee Fund"), StoneBridge 2017 Offshore, L.P. ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds") and Bridge Street Opportunity Advisors, L.L.C ("Bridge Street"). Goldman Sachs is a subsidiary of GS Group. Goldman Sachs is the manager of BSPI and Bridge Street and the investment manager of the Employee Funds. GS Group is the direct owner of Bridge Street. Bridge Street is the general partner of each Employee Fund.

F2 · ownership.nature: On February 14, 2017 MDC Partners Inc. ("MDC Canada") and Broad Street Principal Investments, L.L.C. ("BSPI") entered into a Securities Purchase Agreement (as amended from time to time, the "Purchase Agreement"), pursuant to which MDC Canada agreed to issue and BSPI agreed to purchase (the "Private Placement") 95,000 Series 4 Convertible Preference Shares of MDC Canada (the "Preference Shares").

F3 · ownership.nature: On March 6, 2017 BSPI assigned its right to purchase 11,813 and 4,187 Preference Shares of MDC Canada to StoneBridge 2017, L.P., a Delaware limited partnership ("SB Employee Fund") and StoneBridge 2017 Offshore, L.P., a Cayman Islands exempted limited partnership ("SB Employee Fund Offshore," and together with SB Employee Fund, the "Employee Funds"), respectively, pursuant to two Assignment and Assumption Agreements. GS Group is the direct owner of BSPI and Bridge Street Opportunity Advisors, L.L.C. ("Bridge Street"). Bridge Street is the general partner of each Employee Fund.

F4 · ownership.nature: In December 2020, MDC Canada and Stagwell Media LP ("Stagwell") entered into a transaction agreement (the "Transaction Agreement"), providing for, among other things, the redomiciliation (the "Redomiciliation") of MDC Canada from the federal jurisdiction of Canada to the State of Delaware and the subsequent combination (the "Business Combination") of MDC Canada's business with the business of the subsidiaries of Stagwell that own and operate a portfolio of marketing services companies. The Redomiciliation, the Business Combination, and a series of related transactions are referred to herein as the "Transactions", and following such Business Combination, the combined company is referred to herein as the "Combined Company" or the "Issuer".

F5 · ownership.nature: In connection with the consummation of the Transactions, each Class A Subordinate Voting Share of MDC Canada was converted into one share of Class A common stock, par value $0.001 per share of the Combined Company ("Class A Common Stock"), and each Series 4 Preference Share of MDC Canada was converted into a share of Series 4 Convertible Preferred Stock, par value $0.001 per share of the Combined Company ("Series 4 Preferred Stock").

F6 · ownership.nature: In connection with the closing of the Transactions, on August 4, 2021, (i) the Issuer redeemed 21,151 shares of Series 4 Preferred Stock from BSPI and the Employee Funds (which were convertible into 6,001,218.02 shares of Class A Common Stock) in exchange for $25 million in cash, and (ii) BSPI and the Employee Funds delivered to the issuer, and the Issuer accepted from BSPI and the Employee Funds, 73,849 shares of Series 4 Preferred Stock (which were convertible into 20,953,333.15 shares of Class A Common Stock) in exchange for the issuance to the Holders of 73,849 shares of Series 8 Convertible Preferred Stock, par value $0.001 per share of the Combined Company (the "Series 8 Preferred Stock") having the terms set forth in the certificate of designation designating the Series 8 Preferred Stock.

F7 · ownership.nature: BSPI and the Employee Funds have the right to convert the Series 8 Preferred Stock into shares of Class A Common Stock in whole at any time and from time to time, and in part at any time and from time to time, subject to certain ownership limitations.

F8 · ownership.nature: Because of the relationship by and between GS Group, Goldman Sachs, BSPI and the Employee Funds, GS Group and Goldman Sachs may be deemed (for purposes of Rule 13d-3(a) and Rule 16a-1(a) only and not for any other applicable purpose) to beneficially own an aggregate of 20,991,737.48 shares of Class A Common Stock, consisting of (i) 17,424,273.07 shares of Class A Common Stock (deliverable to BSPI upon conversion of the Series 8 Preferred Stock directly held by BSPI), (ii) 3,529,060.08 shares of Class A Common Stock (deliverable to the Employee Funds upon conversion of the Series 8 Preferred Stock directly held by the Employee Funds), and (iii) Goldman Sachs beneficially owns directly and GS Group may be deemed to beneficially own indirectly 38,404.33 shares of Class A Common Stock.

SEC source: 0001437749-21-018551 · rdgdoc.xml · derivative · entry 1

Penn Mark Jeffery · CIK 0001771735 · Director · CHIEF EXECUTIVE OFFICER · 10% owner

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 0

Underlying: Class A Common Shares · 179,970,051 shares

Expires not disclosed

F1 · derivative.exercise_price: The Reporting Person is the controlling person of Stagwell Media LP ("Stagwell Media"). Stagwell Media directly holds 160,864,073 Class C Common Shares of the Issuer. Stagwell Media is the manager of Stagwell Friends and Family LLC, which directly holds 19,105,978 Class C Common Shares of the Issuer. The Class C Common Shares are voting-only shares that have no economic interest in the Issuer and are not registered or listed shares. The holder of Class C Common Shares, may, at its option, exchange its Class C Common Shares, together with its corresponding economic interest in a wholly-owned subsidiary of the Issuer (collectively, a "Paired Equity Interest"), for Class A Common Shares on a one-to-one basis (i.e., one Paired Equity Interest for one Class A Common Share). The Class C Common Shares are subject to a lock-up agreement that prevents the holder thereof from exchanging such Class C Common Shares for Class A Common Shares until February 2, 2022.

F2 · derivative.expiration_date: The right of any holder of Class C Common Shares to exchange such shares for Class A Common Shares is not subject to an expiration date.

F1 · ownership.nature: The Reporting Person is the controlling person of Stagwell Media LP ("Stagwell Media"). Stagwell Media directly holds 160,864,073 Class C Common Shares of the Issuer. Stagwell Media is the manager of Stagwell Friends and Family LLC, which directly holds 19,105,978 Class C Common Shares of the Issuer. The Class C Common Shares are voting-only shares that have no economic interest in the Issuer and are not registered or listed shares. The holder of Class C Common Shares, may, at its option, exchange its Class C Common Shares, together with its corresponding economic interest in a wholly-owned subsidiary of the Issuer (collectively, a "Paired Equity Interest"), for Class A Common Shares on a one-to-one basis (i.e., one Paired Equity Interest for one Class A Common Share). The Class C Common Shares are subject to a lock-up agreement that prevents the holder thereof from exchanging such Class C Common Shares for Class A Common Shares until February 2, 2022.

SEC source: 0001104659-21-081548 · tm2119828d1_4seq1.xml · nonDerivative · entry 1

DIMAGGIO VINCENZO · CIK 0001808306 · SVP, Chief Accounting Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 67,136

F1 · shares: A total of 25,000 shares of restricted stock (Class A Subordinate Voting Shares) vested on June 11, 2021. The 9,555 shares were withheld by the Issuer to satisfy tax withholding requirements related to the vesting.

F2 · balance_after: Includes 31,691 shares of unvested restricted stock (Class A Subordinate Voting Shares) of the Issuer.

SEC source: 0001104659-21-030946 · tm218483-3_4seq1.xml · nonDerivative · entry 1

Lanuto Frank P · CIK 0001443237 · EVP, Chief Financial Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 194,123

F1 · shares: 99,000 shares of Restricted Stock (Class A Shares) of the Issuer were awarded to the Reporting Person on November 4, 2019, subject to achievement of financial performance targets and continued employment. 4,877 of these shares were forfeited on February 26, 2021 as a result of partial achievement of the financial performance targets. The remaining shares will vest on December 31, 2022, subject to continued employment.

F2 · balance_after: Includes 94,123 shares of unvested Restricted Stock (Class A Shares) of the Issuer.

SEC source: 0001104659-21-030943 · tm218483-2_4seq1.xml · nonDerivative · entry 1

DIMAGGIO VINCENZO · CIK 0001808306 · SVP, Chief Accounting Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 76,691

F1 · shares: 33,333 shares of Restricted Stock (Class A Shares) of the Issuer were awarded to the Reporting Person on November 4, 2019, subject to achievement of financial performance targets and continued employment. 1,642 of these shares were forfeited on February 26, 2021 as a result of partial achievement of the financial performance targets. The remaining shares will vest on December 31, 2022, subject to continued employment.

F2 · balance_after: Includes 56,691 shares of unvested Restricted Stock (Class A Shares) of the Issuer.

SEC source: 0001104659-21-030939 · tm218483-1_4seq1.xml · nonDerivative · entry 1

Penn Mark Jeffery · CIK 0001771735 · Director · Chief Executive Officer · 10% owner

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 574,051

F1 · shares: 577,500 shares of Restricted Stock (Class A Shares) of the Issuer were awarded to the Reporting Person on November 4, 2019, subject to achievement of financial performance targets and continued employment. 28,449 of these shares were forfeited on February 26, 2021 as a result of partial achievement of the financial performance targets. The remaining shares will vest on December 31, 2022, subject to continued employment.

F2 · balance_after: Includes 549,051 shares of unvested Restricted Stock (Class A Shares) of the Issuer.

SEC source: 0001104659-21-030938 · tm218483-4_4seq1.xml · nonDerivative · entry 3

Ross David Corwin · CIK 0001699282 · See Remarks

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 344,327

F3 · shares: 95,488 shares of Restricted Stock (Class A Shares) of the Issuer awarded to the Reporting Person were eligible for vesting on February 26, 2021, subject to achievement of financial performance targets and continued employment. Of these shares, 43,807 were forfeited and 51,681 vested. 26,704 of the vested shares were withheld by the Issuer to satisfy tax withholding requirements related to the vesting.

F2 · balance_after: Includes shares of unvested Restricted Stock (Class A Shares) of the Issuer.

SEC source: 0001104659-21-030938 · tm218483-4_4seq1.xml · nonDerivative · entry 2

Ross David Corwin · CIK 0001699282 · See Remarks

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 371,031

F3 · shares: 95,488 shares of Restricted Stock (Class A Shares) of the Issuer awarded to the Reporting Person were eligible for vesting on February 26, 2021, subject to achievement of financial performance targets and continued employment. Of these shares, 43,807 were forfeited and 51,681 vested. 26,704 of the vested shares were withheld by the Issuer to satisfy tax withholding requirements related to the vesting.

F2 · balance_after: Includes shares of unvested Restricted Stock (Class A Shares) of the Issuer.

SEC source: 0001104659-21-030938 · tm218483-4_4seq1.xml · nonDerivative · entry 1

Ross David Corwin · CIK 0001699282 · See Remarks

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 414,838

F1 · shares: 200,000 shares of Restricted Stock (Class A Shares) of the Issuer were awarded to the Reporting Person on November 4, 2019, subject to achievement of financial performance targets and continued employment. 9,852 of these shares were forfeited on February 26, 2021 as a result of partial achievement of the financial performance targets. The remaining shares will vest on December 31, 2022, subject to continued employment.

F2 · balance_after: Includes shares of unvested Restricted Stock (Class A Shares) of the Issuer.

SEC source: 0001104659-20-111701 · tm2032349d1_4.xml · nonDerivative · entry 2

Mirsky Jonathan B. · CIK 0001780360 · Former General Counsel

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 145,754

F2 · shares: The 105,875 shares of restricted stock were forfeited to the Issuer.

F3 · balance_after: Includes 15,125 shares of unvested restricted stock (Class A Subordinate Voting Shares) of the Issuer.

SEC source: 0001104659-20-111701 · tm2032349d1_4.xml · nonDerivative · entry 1

Mirsky Jonathan B. · CIK 0001780360 · Former General Counsel

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 251,269

F1 · shares: A total of 166,666 shares of restricted stock (Class A Subordinate Voting Shares) vested on September 30, 2020. The 80,121 shares were withheld by the Issuer to satisfy tax withholding requirements related to the vesting.

SEC source: 0001104659-20-093386 · tm2027254d5_4.xml · nonDerivative · entry 1

Oosterman Wade · CIK 0001587270 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 58,256

F1 · shares: The reporting person was awarded restricted stock units as a component of non-employee director compensation. Each restricted stock unit represents a contingent right to receive one Class A Subordinate Voting Share. The restricted stock units will vest in full on the first anniversary of the date of grant.

SEC source: 0001104659-20-093385 · tm2027254d4_4.xml · nonDerivative · entry 1

ROGERS DESIREE G · CIK 0001182862 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 72,218

F1 · shares: The reporting person was awarded shares of restricted stock (Class A Subordinate Voting Shares) as a component of non-employee director compensation. The shares of restricted stock will vest in full on the first anniversary of the date of grant.

F2 · balance_after: Includes shares of unvested restricted stock (Class A Subordinate Voting Shares).