CTOS

SEC source: 0000899243-22-007083 · doc4.xml · nonDerivative · entry 6

Blackstone Holdings III L.P. · CIK 0001404073 · Former 10% Owner

Blackstone Inc · CIK 0001393818 · Former 10% Owner

Blackstone Group Management L.L.C. · CIK 0001404071 · Former 10% Owner

SCHWARZMAN STEPHEN A · CIK 0001070844 · Former 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: 0

F1 · price: This amount represents the price per share of common stock, par value $0.0001 per share ("Common Stock"), of Custom Truck One Source, Inc. (the "Issuer") sold in a transaction exempt from registration pursuant to Rule 144 promulgated under the Securities Act of 1933, as amended.

F7 · ownership.nature: Reflects shares of Common Stock directly held by BCP CTOS Holdings L.P. ("BCP CTOS").

F9 · ownership.nature: Blackstone Energy Management Associates NQ L.L.C. ("BEMA") is the general partner of BEP NQ and BEP CTOS. Blackstone EMA-NQ L.L.C. ("BEMA NQ") is the managing member of BEMA. BEP Side-by-Side GP NQ L.L.C. ("BEP GP") is the general partner of BE NQ. Blackstone Management Associates VI-NQ L.L.C. ("BMA NQ") is the general partner of BCP VI-NQ and BCP CTOS. BMA VI-NQ L.L.C. ("BMA VI-NQ") is the managing member of BMA NQ. Blackstone Family GP L.L.C. ("BS GP") is the general partner of BE SMD. BS GP is wholly-owned by Blackstone's senior managing directors and controlled by its founder, Stephen A. Schwarzman. BCP VI-NQ Side-by-Side GP L.L.C. ("BCP GP") is the general partner of BE FIP.

F10 · ownership.nature: Blackstone Holdings III L.P. ("Holdings III") is the sole member of each of BEMA NQ, BEP GP and BMA VI-NQ. The general partner of Holdings III is Blackstone Holdings III GP L.P. ("Holdings III GP"). The general partner of Holdings III GP is Blackstone Holdings III GP Management L.L.C ("Holdings III GP Management"). Blackstone Holdings II L.P. ("Holdings II") is the sole member of BCP GP. Blackstone Holdings I/II GP L.L.C. ("Holdings I/II GP") is the general partner of Holdings II. Blackstone Inc. ("Blackstone") is the sole member of Holdings III GP Management and Holdings I/II GP. The sole holder of the Series II preferred stock of Blackstone is Blackstone Group Management L.L.C. ("BS Group Management"). BS Group Management is wholly-owned by Blackstone's senior managing directors and controlled by its founder, Stephen A. Schwarzman.

F11 · ownership.nature: Information with respect to each of the Reporting Persons is given solely by such Reporting Person, and no Reporting Person has responsibility for the accuracy or completeness of information supplied by another Reporting Person.

F12 · ownership.nature: Due to the limitations of the electronic filing system certain Reporting Persons are filing a separate Form 4.

F13 · ownership.nature: Each of the Reporting Persons (other than to the extent it directly holds securities reported herein) disclaims beneficial ownership of the securities held by the other Reporting Persons, except to the extent of such Reporting Person's pecuniary interest therein, and, pursuant to Rule 16a-1(a)(4) under the Securities Exchange Act of 1934 (the "Exchange Act"), each of the Reporting Persons (other than to the extent it directly holds securities reported herein) states that the inclusion of these securities in this report shall not be deemed an admission of beneficial ownership of all of the securities reported herein for purposes of Section 16 of the Exchange Act or for any other purpose or that the Reporting Persons are subject to Section 16 of the Exchange Act.

SEC source: 0000899243-22-007083 · doc4.xml · nonDerivative · entry 5

Blackstone Holdings III L.P. · CIK 0001404073 · Former 10% Owner

Blackstone Inc · CIK 0001393818 · Former 10% Owner

Blackstone Group Management L.L.C. · CIK 0001404071 · Former 10% Owner

SCHWARZMAN STEPHEN A · CIK 0001070844 · Former 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: 0

F1 · price: This amount represents the price per share of common stock, par value $0.0001 per share ("Common Stock"), of Custom Truck One Source, Inc. (the "Issuer") sold in a transaction exempt from registration pursuant to Rule 144 promulgated under the Securities Act of 1933, as amended.

F6 · ownership.nature: Reflects shares of Common Stock directly held by Blackstone Capital Partners VI-NQ L.P. ("BCP VI-NQ").

F9 · ownership.nature: Blackstone Energy Management Associates NQ L.L.C. ("BEMA") is the general partner of BEP NQ and BEP CTOS. Blackstone EMA-NQ L.L.C. ("BEMA NQ") is the managing member of BEMA. BEP Side-by-Side GP NQ L.L.C. ("BEP GP") is the general partner of BE NQ. Blackstone Management Associates VI-NQ L.L.C. ("BMA NQ") is the general partner of BCP VI-NQ and BCP CTOS. BMA VI-NQ L.L.C. ("BMA VI-NQ") is the managing member of BMA NQ. Blackstone Family GP L.L.C. ("BS GP") is the general partner of BE SMD. BS GP is wholly-owned by Blackstone's senior managing directors and controlled by its founder, Stephen A. Schwarzman. BCP VI-NQ Side-by-Side GP L.L.C. ("BCP GP") is the general partner of BE FIP.

F10 · ownership.nature: Blackstone Holdings III L.P. ("Holdings III") is the sole member of each of BEMA NQ, BEP GP and BMA VI-NQ. The general partner of Holdings III is Blackstone Holdings III GP L.P. ("Holdings III GP"). The general partner of Holdings III GP is Blackstone Holdings III GP Management L.L.C ("Holdings III GP Management"). Blackstone Holdings II L.P. ("Holdings II") is the sole member of BCP GP. Blackstone Holdings I/II GP L.L.C. ("Holdings I/II GP") is the general partner of Holdings II. Blackstone Inc. ("Blackstone") is the sole member of Holdings III GP Management and Holdings I/II GP. The sole holder of the Series II preferred stock of Blackstone is Blackstone Group Management L.L.C. ("BS Group Management"). BS Group Management is wholly-owned by Blackstone's senior managing directors and controlled by its founder, Stephen A. Schwarzman.

F11 · ownership.nature: Information with respect to each of the Reporting Persons is given solely by such Reporting Person, and no Reporting Person has responsibility for the accuracy or completeness of information supplied by another Reporting Person.

F12 · ownership.nature: Due to the limitations of the electronic filing system certain Reporting Persons are filing a separate Form 4.

F13 · ownership.nature: Each of the Reporting Persons (other than to the extent it directly holds securities reported herein) disclaims beneficial ownership of the securities held by the other Reporting Persons, except to the extent of such Reporting Person's pecuniary interest therein, and, pursuant to Rule 16a-1(a)(4) under the Securities Exchange Act of 1934 (the "Exchange Act"), each of the Reporting Persons (other than to the extent it directly holds securities reported herein) states that the inclusion of these securities in this report shall not be deemed an admission of beneficial ownership of all of the securities reported herein for purposes of Section 16 of the Exchange Act or for any other purpose or that the Reporting Persons are subject to Section 16 of the Exchange Act.

SEC source: 0000899243-22-007083 · doc4.xml · nonDerivative · entry 4

Blackstone Holdings III L.P. · CIK 0001404073 · Former 10% Owner

Blackstone Inc · CIK 0001393818 · Former 10% Owner

Blackstone Group Management L.L.C. · CIK 0001404071 · Former 10% Owner

SCHWARZMAN STEPHEN A · CIK 0001070844 · Former 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: 0

F1 · price: This amount represents the price per share of common stock, par value $0.0001 per share ("Common Stock"), of Custom Truck One Source, Inc. (the "Issuer") sold in a transaction exempt from registration pursuant to Rule 144 promulgated under the Securities Act of 1933, as amended.

F5 · ownership.nature: Reflects shares of Common Stock directly held by Blackstone Energy Family Investment Partnership NQ ESC L.P. ("BE NQ").

F9 · ownership.nature: Blackstone Energy Management Associates NQ L.L.C. ("BEMA") is the general partner of BEP NQ and BEP CTOS. Blackstone EMA-NQ L.L.C. ("BEMA NQ") is the managing member of BEMA. BEP Side-by-Side GP NQ L.L.C. ("BEP GP") is the general partner of BE NQ. Blackstone Management Associates VI-NQ L.L.C. ("BMA NQ") is the general partner of BCP VI-NQ and BCP CTOS. BMA VI-NQ L.L.C. ("BMA VI-NQ") is the managing member of BMA NQ. Blackstone Family GP L.L.C. ("BS GP") is the general partner of BE SMD. BS GP is wholly-owned by Blackstone's senior managing directors and controlled by its founder, Stephen A. Schwarzman. BCP VI-NQ Side-by-Side GP L.L.C. ("BCP GP") is the general partner of BE FIP.

F10 · ownership.nature: Blackstone Holdings III L.P. ("Holdings III") is the sole member of each of BEMA NQ, BEP GP and BMA VI-NQ. The general partner of Holdings III is Blackstone Holdings III GP L.P. ("Holdings III GP"). The general partner of Holdings III GP is Blackstone Holdings III GP Management L.L.C ("Holdings III GP Management"). Blackstone Holdings II L.P. ("Holdings II") is the sole member of BCP GP. Blackstone Holdings I/II GP L.L.C. ("Holdings I/II GP") is the general partner of Holdings II. Blackstone Inc. ("Blackstone") is the sole member of Holdings III GP Management and Holdings I/II GP. The sole holder of the Series II preferred stock of Blackstone is Blackstone Group Management L.L.C. ("BS Group Management"). BS Group Management is wholly-owned by Blackstone's senior managing directors and controlled by its founder, Stephen A. Schwarzman.

F11 · ownership.nature: Information with respect to each of the Reporting Persons is given solely by such Reporting Person, and no Reporting Person has responsibility for the accuracy or completeness of information supplied by another Reporting Person.

F12 · ownership.nature: Due to the limitations of the electronic filing system certain Reporting Persons are filing a separate Form 4.

F13 · ownership.nature: Each of the Reporting Persons (other than to the extent it directly holds securities reported herein) disclaims beneficial ownership of the securities held by the other Reporting Persons, except to the extent of such Reporting Person's pecuniary interest therein, and, pursuant to Rule 16a-1(a)(4) under the Securities Exchange Act of 1934 (the "Exchange Act"), each of the Reporting Persons (other than to the extent it directly holds securities reported herein) states that the inclusion of these securities in this report shall not be deemed an admission of beneficial ownership of all of the securities reported herein for purposes of Section 16 of the Exchange Act or for any other purpose or that the Reporting Persons are subject to Section 16 of the Exchange Act.

SEC source: 0000899243-22-007083 · doc4.xml · nonDerivative · entry 3

Blackstone Holdings III L.P. · CIK 0001404073 · Former 10% Owner

Blackstone Inc · CIK 0001393818 · Former 10% Owner

Blackstone Group Management L.L.C. · CIK 0001404071 · Former 10% Owner

SCHWARZMAN STEPHEN A · CIK 0001070844 · Former 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: 0

F1 · price: This amount represents the price per share of common stock, par value $0.0001 per share ("Common Stock"), of Custom Truck One Source, Inc. (the "Issuer") sold in a transaction exempt from registration pursuant to Rule 144 promulgated under the Securities Act of 1933, as amended.

F4 · ownership.nature: Reflects shares of Common Stock directly held by Blackstone Energy Family Investment Partnership SMD L.P. ("BE SMD").

F9 · ownership.nature: Blackstone Energy Management Associates NQ L.L.C. ("BEMA") is the general partner of BEP NQ and BEP CTOS. Blackstone EMA-NQ L.L.C. ("BEMA NQ") is the managing member of BEMA. BEP Side-by-Side GP NQ L.L.C. ("BEP GP") is the general partner of BE NQ. Blackstone Management Associates VI-NQ L.L.C. ("BMA NQ") is the general partner of BCP VI-NQ and BCP CTOS. BMA VI-NQ L.L.C. ("BMA VI-NQ") is the managing member of BMA NQ. Blackstone Family GP L.L.C. ("BS GP") is the general partner of BE SMD. BS GP is wholly-owned by Blackstone's senior managing directors and controlled by its founder, Stephen A. Schwarzman. BCP VI-NQ Side-by-Side GP L.L.C. ("BCP GP") is the general partner of BE FIP.

F10 · ownership.nature: Blackstone Holdings III L.P. ("Holdings III") is the sole member of each of BEMA NQ, BEP GP and BMA VI-NQ. The general partner of Holdings III is Blackstone Holdings III GP L.P. ("Holdings III GP"). The general partner of Holdings III GP is Blackstone Holdings III GP Management L.L.C ("Holdings III GP Management"). Blackstone Holdings II L.P. ("Holdings II") is the sole member of BCP GP. Blackstone Holdings I/II GP L.L.C. ("Holdings I/II GP") is the general partner of Holdings II. Blackstone Inc. ("Blackstone") is the sole member of Holdings III GP Management and Holdings I/II GP. The sole holder of the Series II preferred stock of Blackstone is Blackstone Group Management L.L.C. ("BS Group Management"). BS Group Management is wholly-owned by Blackstone's senior managing directors and controlled by its founder, Stephen A. Schwarzman.

F11 · ownership.nature: Information with respect to each of the Reporting Persons is given solely by such Reporting Person, and no Reporting Person has responsibility for the accuracy or completeness of information supplied by another Reporting Person.

F12 · ownership.nature: Due to the limitations of the electronic filing system certain Reporting Persons are filing a separate Form 4.

F13 · ownership.nature: Each of the Reporting Persons (other than to the extent it directly holds securities reported herein) disclaims beneficial ownership of the securities held by the other Reporting Persons, except to the extent of such Reporting Person's pecuniary interest therein, and, pursuant to Rule 16a-1(a)(4) under the Securities Exchange Act of 1934 (the "Exchange Act"), each of the Reporting Persons (other than to the extent it directly holds securities reported herein) states that the inclusion of these securities in this report shall not be deemed an admission of beneficial ownership of all of the securities reported herein for purposes of Section 16 of the Exchange Act or for any other purpose or that the Reporting Persons are subject to Section 16 of the Exchange Act.

SEC source: 0000899243-22-007083 · doc4.xml · nonDerivative · entry 2

Blackstone Holdings III L.P. · CIK 0001404073 · Former 10% Owner

Blackstone Inc · CIK 0001393818 · Former 10% Owner

Blackstone Group Management L.L.C. · CIK 0001404071 · Former 10% Owner

SCHWARZMAN STEPHEN A · CIK 0001070844 · Former 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: 0

F1 · price: This amount represents the price per share of common stock, par value $0.0001 per share ("Common Stock"), of Custom Truck One Source, Inc. (the "Issuer") sold in a transaction exempt from registration pursuant to Rule 144 promulgated under the Securities Act of 1933, as amended.

F3 · ownership.nature: Reflects shares of Common Stock directly held by BEP CTOS Holdings L.P. ("BEP CTOS").

F9 · ownership.nature: Blackstone Energy Management Associates NQ L.L.C. ("BEMA") is the general partner of BEP NQ and BEP CTOS. Blackstone EMA-NQ L.L.C. ("BEMA NQ") is the managing member of BEMA. BEP Side-by-Side GP NQ L.L.C. ("BEP GP") is the general partner of BE NQ. Blackstone Management Associates VI-NQ L.L.C. ("BMA NQ") is the general partner of BCP VI-NQ and BCP CTOS. BMA VI-NQ L.L.C. ("BMA VI-NQ") is the managing member of BMA NQ. Blackstone Family GP L.L.C. ("BS GP") is the general partner of BE SMD. BS GP is wholly-owned by Blackstone's senior managing directors and controlled by its founder, Stephen A. Schwarzman. BCP VI-NQ Side-by-Side GP L.L.C. ("BCP GP") is the general partner of BE FIP.

F10 · ownership.nature: Blackstone Holdings III L.P. ("Holdings III") is the sole member of each of BEMA NQ, BEP GP and BMA VI-NQ. The general partner of Holdings III is Blackstone Holdings III GP L.P. ("Holdings III GP"). The general partner of Holdings III GP is Blackstone Holdings III GP Management L.L.C ("Holdings III GP Management"). Blackstone Holdings II L.P. ("Holdings II") is the sole member of BCP GP. Blackstone Holdings I/II GP L.L.C. ("Holdings I/II GP") is the general partner of Holdings II. Blackstone Inc. ("Blackstone") is the sole member of Holdings III GP Management and Holdings I/II GP. The sole holder of the Series II preferred stock of Blackstone is Blackstone Group Management L.L.C. ("BS Group Management"). BS Group Management is wholly-owned by Blackstone's senior managing directors and controlled by its founder, Stephen A. Schwarzman.

F11 · ownership.nature: Information with respect to each of the Reporting Persons is given solely by such Reporting Person, and no Reporting Person has responsibility for the accuracy or completeness of information supplied by another Reporting Person.

F12 · ownership.nature: Due to the limitations of the electronic filing system certain Reporting Persons are filing a separate Form 4.

F13 · ownership.nature: Each of the Reporting Persons (other than to the extent it directly holds securities reported herein) disclaims beneficial ownership of the securities held by the other Reporting Persons, except to the extent of such Reporting Person's pecuniary interest therein, and, pursuant to Rule 16a-1(a)(4) under the Securities Exchange Act of 1934 (the "Exchange Act"), each of the Reporting Persons (other than to the extent it directly holds securities reported herein) states that the inclusion of these securities in this report shall not be deemed an admission of beneficial ownership of all of the securities reported herein for purposes of Section 16 of the Exchange Act or for any other purpose or that the Reporting Persons are subject to Section 16 of the Exchange Act.

SEC source: 0000899243-22-007083 · doc4.xml · nonDerivative · entry 1

Blackstone Holdings III L.P. · CIK 0001404073 · Former 10% Owner

Blackstone Inc · CIK 0001393818 · Former 10% Owner

Blackstone Group Management L.L.C. · CIK 0001404071 · Former 10% Owner

SCHWARZMAN STEPHEN A · CIK 0001070844 · Former 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: 0

F1 · price: This amount represents the price per share of common stock, par value $0.0001 per share ("Common Stock"), of Custom Truck One Source, Inc. (the "Issuer") sold in a transaction exempt from registration pursuant to Rule 144 promulgated under the Securities Act of 1933, as amended.

F2 · ownership.nature: Reflects shares of Common Stock directly held by Blackstone Energy Partners NQ L.P. ("BEP NQ").

F9 · ownership.nature: Blackstone Energy Management Associates NQ L.L.C. ("BEMA") is the general partner of BEP NQ and BEP CTOS. Blackstone EMA-NQ L.L.C. ("BEMA NQ") is the managing member of BEMA. BEP Side-by-Side GP NQ L.L.C. ("BEP GP") is the general partner of BE NQ. Blackstone Management Associates VI-NQ L.L.C. ("BMA NQ") is the general partner of BCP VI-NQ and BCP CTOS. BMA VI-NQ L.L.C. ("BMA VI-NQ") is the managing member of BMA NQ. Blackstone Family GP L.L.C. ("BS GP") is the general partner of BE SMD. BS GP is wholly-owned by Blackstone's senior managing directors and controlled by its founder, Stephen A. Schwarzman. BCP VI-NQ Side-by-Side GP L.L.C. ("BCP GP") is the general partner of BE FIP.

F10 · ownership.nature: Blackstone Holdings III L.P. ("Holdings III") is the sole member of each of BEMA NQ, BEP GP and BMA VI-NQ. The general partner of Holdings III is Blackstone Holdings III GP L.P. ("Holdings III GP"). The general partner of Holdings III GP is Blackstone Holdings III GP Management L.L.C ("Holdings III GP Management"). Blackstone Holdings II L.P. ("Holdings II") is the sole member of BCP GP. Blackstone Holdings I/II GP L.L.C. ("Holdings I/II GP") is the general partner of Holdings II. Blackstone Inc. ("Blackstone") is the sole member of Holdings III GP Management and Holdings I/II GP. The sole holder of the Series II preferred stock of Blackstone is Blackstone Group Management L.L.C. ("BS Group Management"). BS Group Management is wholly-owned by Blackstone's senior managing directors and controlled by its founder, Stephen A. Schwarzman.

F11 · ownership.nature: Information with respect to each of the Reporting Persons is given solely by such Reporting Person, and no Reporting Person has responsibility for the accuracy or completeness of information supplied by another Reporting Person.

F12 · ownership.nature: Due to the limitations of the electronic filing system certain Reporting Persons are filing a separate Form 4.

F13 · ownership.nature: Each of the Reporting Persons (other than to the extent it directly holds securities reported herein) disclaims beneficial ownership of the securities held by the other Reporting Persons, except to the extent of such Reporting Person's pecuniary interest therein, and, pursuant to Rule 16a-1(a)(4) under the Securities Exchange Act of 1934 (the "Exchange Act"), each of the Reporting Persons (other than to the extent it directly holds securities reported herein) states that the inclusion of these securities in this report shall not be deemed an admission of beneficial ownership of all of the securities reported herein for purposes of Section 16 of the Exchange Act or for any other purpose or that the Reporting Persons are subject to Section 16 of the Exchange Act.

SEC source: 0001213900-21-065461 · ownership.xml · nonDerivative · entry 1

Rich Thomas R. · CIK 0001854514 · EVP - Rentals

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 35,857

F1 · price: The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions ranging from $7.598 to $7.63, inclusive. The Reporting Person undertakes to provide to the Issuer, any securityholder 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 range set forth above.

SEC source: 0001213900-21-063942 · ownership.xml · nonDerivative · entry 2

Carlsen James · CIK 0001854934 · CIO

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 41,974

F2 · price: The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions ranging from $7.785 to $7.8199, inclusive. The Reporting Person undertakes to provide to the Issuer, any securityholder 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 range set forth above.

SEC source: 0001213900-21-063942 · ownership.xml · nonDerivative · entry 1

Carlsen James · CIK 0001854934 · CIO

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 36,974

F1 · price: The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions ranging from $7.3499 to $7.50, inclusive. The Reporting Person undertakes to provide to the Issuer, any securityholder 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 range set forth above.

SEC source: 0000899243-21-045646 · doc4.xml · nonDerivative · entry 7

Blackstone Energy Partners NQ L.P. · CIK 0001855931 · 10% owner

BEP CTOS Holdings L.P. · CIK 0001857352 · 10% owner

Blackstone Energy Family Investment Partnership SMD L.P. · CIK 0001851447 · 10% owner

Blackstone Energy Family Investment Partnership NQ ESC L.P. · CIK 0001855942 · 10% owner

Blackstone Capital Partners VI-NQ L.P. · CIK 0001855944 · 10% owner

BCP CTOS Holdings L.P. · CIK 0001857351 · 10% owner

Blackstone Family Investment Partnership VI-NQ ESC L.P. · CIK 0001856558 · 10% owner

Blackstone Energy Management Associates NQ L.L.C. · CIK 0001855939 · 10% owner

Blackstone EMA-NQ L.L.C. · CIK 0001855943 · 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: 2,264

F1 · price: This amount represents the $8.5000 public offering price per share of common stock, par value $0.0001 per share ("Common Stock"), of Custom Truck One Source, Inc. (the "Issuer"), less the underwriting discount of $0.02975 per share. The Underwriters have not yet exercised their Over-allotment Option to purchase additional shares of Common Stock.

F8 · ownership.nature: Reflects shares of Common Stock directly held by Blackstone Family Investment Partnership VI-NQ ESC L.P. ("BE FIP").

F9 · ownership.nature: Blackstone Energy Management Associates NQ L.L.C. ("BEMA") is the general partner of BEP NQ and BEP CTOS. Blackstone EMA-NQ L.L.C. ("BEMA NQ") is the managing member of BEMA. BEP Side-by-Side GP NQ L.L.C. ("BEP GP") is the general partner of BE NQ. Blackstone Management Associates VI-NQ L.L.C. ("BMA NQ") is the general partner of BCP VI-NQ and BCP CTOS. BMA VI-NQ L.L.C. ("BMA VI-NQ") is the managing member of BMA NQ. Blackstone Family GP L.L.C. ("BS GP") is the general partner of BE SMD. BS GP is wholly-owned by Blackstone's senior managing directors and controlled by its founder, Stephen A. Schwarzman. BCP VI-NQ Side-by-Side GP L.L.C. ("BCP GP") is the general partner of BE FIP.

F10 · ownership.nature: Blackstone Holdings III L.P. ("Holdings III") is the sole member of each of BEMA NQ, BEP GP and BMA VI-NQ. The general partner of Holdings III is Blackstone Holdings III GP L.P. ("Holdings III GP"). The general partner of Holdings III GP is Blackstone Holdings III GP Management L.L.C ("Holdings III GP Management"). Blackstone Holdings II L.P. ("Holdings II") is the sole member of BCP GP. Blackstone Holdings I/II GP L.L.C. ("Holdings I/II GP") is the general partner of Holdings II. Blackstone Inc. ("Blackstone") is the sole member of Holdings III GP Management and Holdings I/II GP. The sole holder of the Series II preferred stock of Blackstone is Blackstone Group Management L.L.C. ("BS Group Management"). BS Group Management is wholly-owned by Blackstone's senior managing directors and controlled by its founder, Stephen A. Schwarzman.

F11 · ownership.nature: Information with respect to each of the Reporting Persons is given solely by such Reporting Person, and no Reporting Person has responsibility for the accuracy or completeness of information supplied by another Reporting Person.

F12 · ownership.nature: Due to the limitations of the electronic filing system certain Reporting Persons are filing a separate Form 4.

F13 · ownership.nature: Each of the Reporting Persons (other than to the extent it directly holds securities reported herein) disclaims beneficial ownership of the securities held by the other Reporting Persons, except to the extent of such Reporting Person's pecuniary interest therein, and, pursuant to Rule 16a-1(a)(4) under the Securities Exchange Act of 1934 (the "Exchange Act"), each of the Reporting Persons (other than to the extent it directly holds securities reported herein) states that the inclusion of these securities in this report shall not be deemed an admission of beneficial ownership of all of the securities reported herein for purposes of Section 16 of the Exchange Act or for any other purpose or that the Reporting Persons are subject to Section 16 of the Exchange Act.

SEC source: 0000899243-21-045646 · doc4.xml · nonDerivative · entry 6

Blackstone Energy Partners NQ L.P. · CIK 0001855931 · 10% owner

BEP CTOS Holdings L.P. · CIK 0001857352 · 10% owner

Blackstone Energy Family Investment Partnership SMD L.P. · CIK 0001851447 · 10% owner

Blackstone Energy Family Investment Partnership NQ ESC L.P. · CIK 0001855942 · 10% owner

Blackstone Capital Partners VI-NQ L.P. · CIK 0001855944 · 10% owner

BCP CTOS Holdings L.P. · CIK 0001857351 · 10% owner

Blackstone Family Investment Partnership VI-NQ ESC L.P. · CIK 0001856558 · 10% owner

Blackstone Energy Management Associates NQ L.L.C. · CIK 0001855939 · 10% owner

Blackstone EMA-NQ L.L.C. · CIK 0001855943 · 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: 466,472

F1 · price: This amount represents the $8.5000 public offering price per share of common stock, par value $0.0001 per share ("Common Stock"), of Custom Truck One Source, Inc. (the "Issuer"), less the underwriting discount of $0.02975 per share. The Underwriters have not yet exercised their Over-allotment Option to purchase additional shares of Common Stock.

F7 · ownership.nature: Reflects shares of Common Stock directly held by BCP CTOS Holdings L.P. ("BCP CTOS").

F9 · ownership.nature: Blackstone Energy Management Associates NQ L.L.C. ("BEMA") is the general partner of BEP NQ and BEP CTOS. Blackstone EMA-NQ L.L.C. ("BEMA NQ") is the managing member of BEMA. BEP Side-by-Side GP NQ L.L.C. ("BEP GP") is the general partner of BE NQ. Blackstone Management Associates VI-NQ L.L.C. ("BMA NQ") is the general partner of BCP VI-NQ and BCP CTOS. BMA VI-NQ L.L.C. ("BMA VI-NQ") is the managing member of BMA NQ. Blackstone Family GP L.L.C. ("BS GP") is the general partner of BE SMD. BS GP is wholly-owned by Blackstone's senior managing directors and controlled by its founder, Stephen A. Schwarzman. BCP VI-NQ Side-by-Side GP L.L.C. ("BCP GP") is the general partner of BE FIP.

F10 · ownership.nature: Blackstone Holdings III L.P. ("Holdings III") is the sole member of each of BEMA NQ, BEP GP and BMA VI-NQ. The general partner of Holdings III is Blackstone Holdings III GP L.P. ("Holdings III GP"). The general partner of Holdings III GP is Blackstone Holdings III GP Management L.L.C ("Holdings III GP Management"). Blackstone Holdings II L.P. ("Holdings II") is the sole member of BCP GP. Blackstone Holdings I/II GP L.L.C. ("Holdings I/II GP") is the general partner of Holdings II. Blackstone Inc. ("Blackstone") is the sole member of Holdings III GP Management and Holdings I/II GP. The sole holder of the Series II preferred stock of Blackstone is Blackstone Group Management L.L.C. ("BS Group Management"). BS Group Management is wholly-owned by Blackstone's senior managing directors and controlled by its founder, Stephen A. Schwarzman.

F11 · ownership.nature: Information with respect to each of the Reporting Persons is given solely by such Reporting Person, and no Reporting Person has responsibility for the accuracy or completeness of information supplied by another Reporting Person.

F12 · ownership.nature: Due to the limitations of the electronic filing system certain Reporting Persons are filing a separate Form 4.

F13 · ownership.nature: Each of the Reporting Persons (other than to the extent it directly holds securities reported herein) disclaims beneficial ownership of the securities held by the other Reporting Persons, except to the extent of such Reporting Person's pecuniary interest therein, and, pursuant to Rule 16a-1(a)(4) under the Securities Exchange Act of 1934 (the "Exchange Act"), each of the Reporting Persons (other than to the extent it directly holds securities reported herein) states that the inclusion of these securities in this report shall not be deemed an admission of beneficial ownership of all of the securities reported herein for purposes of Section 16 of the Exchange Act or for any other purpose or that the Reporting Persons are subject to Section 16 of the Exchange Act.

SEC source: 0000899243-21-045646 · doc4.xml · nonDerivative · entry 5

Blackstone Energy Partners NQ L.P. · CIK 0001855931 · 10% owner

BEP CTOS Holdings L.P. · CIK 0001857352 · 10% owner

Blackstone Energy Family Investment Partnership SMD L.P. · CIK 0001851447 · 10% owner

Blackstone Energy Family Investment Partnership NQ ESC L.P. · CIK 0001855942 · 10% owner

Blackstone Capital Partners VI-NQ L.P. · CIK 0001855944 · 10% owner

BCP CTOS Holdings L.P. · CIK 0001857351 · 10% owner

Blackstone Family Investment Partnership VI-NQ ESC L.P. · CIK 0001856558 · 10% owner

Blackstone Energy Management Associates NQ L.L.C. · CIK 0001855939 · 10% owner

Blackstone EMA-NQ L.L.C. · CIK 0001855943 · 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: 455,487

F1 · price: This amount represents the $8.5000 public offering price per share of common stock, par value $0.0001 per share ("Common Stock"), of Custom Truck One Source, Inc. (the "Issuer"), less the underwriting discount of $0.02975 per share. The Underwriters have not yet exercised their Over-allotment Option to purchase additional shares of Common Stock.

F6 · ownership.nature: Reflects shares of Common Stock directly held by Blackstone Capital Partners VI-NQ L.P. ("BCP VI-NQ").

F9 · ownership.nature: Blackstone Energy Management Associates NQ L.L.C. ("BEMA") is the general partner of BEP NQ and BEP CTOS. Blackstone EMA-NQ L.L.C. ("BEMA NQ") is the managing member of BEMA. BEP Side-by-Side GP NQ L.L.C. ("BEP GP") is the general partner of BE NQ. Blackstone Management Associates VI-NQ L.L.C. ("BMA NQ") is the general partner of BCP VI-NQ and BCP CTOS. BMA VI-NQ L.L.C. ("BMA VI-NQ") is the managing member of BMA NQ. Blackstone Family GP L.L.C. ("BS GP") is the general partner of BE SMD. BS GP is wholly-owned by Blackstone's senior managing directors and controlled by its founder, Stephen A. Schwarzman. BCP VI-NQ Side-by-Side GP L.L.C. ("BCP GP") is the general partner of BE FIP.

F10 · ownership.nature: Blackstone Holdings III L.P. ("Holdings III") is the sole member of each of BEMA NQ, BEP GP and BMA VI-NQ. The general partner of Holdings III is Blackstone Holdings III GP L.P. ("Holdings III GP"). The general partner of Holdings III GP is Blackstone Holdings III GP Management L.L.C ("Holdings III GP Management"). Blackstone Holdings II L.P. ("Holdings II") is the sole member of BCP GP. Blackstone Holdings I/II GP L.L.C. ("Holdings I/II GP") is the general partner of Holdings II. Blackstone Inc. ("Blackstone") is the sole member of Holdings III GP Management and Holdings I/II GP. The sole holder of the Series II preferred stock of Blackstone is Blackstone Group Management L.L.C. ("BS Group Management"). BS Group Management is wholly-owned by Blackstone's senior managing directors and controlled by its founder, Stephen A. Schwarzman.

F11 · ownership.nature: Information with respect to each of the Reporting Persons is given solely by such Reporting Person, and no Reporting Person has responsibility for the accuracy or completeness of information supplied by another Reporting Person.

F12 · ownership.nature: Due to the limitations of the electronic filing system certain Reporting Persons are filing a separate Form 4.

F13 · ownership.nature: Each of the Reporting Persons (other than to the extent it directly holds securities reported herein) disclaims beneficial ownership of the securities held by the other Reporting Persons, except to the extent of such Reporting Person's pecuniary interest therein, and, pursuant to Rule 16a-1(a)(4) under the Securities Exchange Act of 1934 (the "Exchange Act"), each of the Reporting Persons (other than to the extent it directly holds securities reported herein) states that the inclusion of these securities in this report shall not be deemed an admission of beneficial ownership of all of the securities reported herein for purposes of Section 16 of the Exchange Act or for any other purpose or that the Reporting Persons are subject to Section 16 of the Exchange Act.

SEC source: 0000899243-21-045646 · doc4.xml · nonDerivative · entry 4

Blackstone Energy Partners NQ L.P. · CIK 0001855931 · 10% owner

BEP CTOS Holdings L.P. · CIK 0001857352 · 10% owner

Blackstone Energy Family Investment Partnership SMD L.P. · CIK 0001851447 · 10% owner

Blackstone Energy Family Investment Partnership NQ ESC L.P. · CIK 0001855942 · 10% owner

Blackstone Capital Partners VI-NQ L.P. · CIK 0001855944 · 10% owner

BCP CTOS Holdings L.P. · CIK 0001857351 · 10% owner

Blackstone Family Investment Partnership VI-NQ ESC L.P. · CIK 0001856558 · 10% owner

Blackstone Energy Management Associates NQ L.L.C. · CIK 0001855939 · 10% owner

Blackstone EMA-NQ L.L.C. · CIK 0001855943 · 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: 23,457

F1 · price: This amount represents the $8.5000 public offering price per share of common stock, par value $0.0001 per share ("Common Stock"), of Custom Truck One Source, Inc. (the "Issuer"), less the underwriting discount of $0.02975 per share. The Underwriters have not yet exercised their Over-allotment Option to purchase additional shares of Common Stock.

F5 · ownership.nature: Reflects shares of Common Stock directly held by Blackstone Energy Family Investment Partnership NQ ESC L.P. ("BE NQ").

F9 · ownership.nature: Blackstone Energy Management Associates NQ L.L.C. ("BEMA") is the general partner of BEP NQ and BEP CTOS. Blackstone EMA-NQ L.L.C. ("BEMA NQ") is the managing member of BEMA. BEP Side-by-Side GP NQ L.L.C. ("BEP GP") is the general partner of BE NQ. Blackstone Management Associates VI-NQ L.L.C. ("BMA NQ") is the general partner of BCP VI-NQ and BCP CTOS. BMA VI-NQ L.L.C. ("BMA VI-NQ") is the managing member of BMA NQ. Blackstone Family GP L.L.C. ("BS GP") is the general partner of BE SMD. BS GP is wholly-owned by Blackstone's senior managing directors and controlled by its founder, Stephen A. Schwarzman. BCP VI-NQ Side-by-Side GP L.L.C. ("BCP GP") is the general partner of BE FIP.

F10 · ownership.nature: Blackstone Holdings III L.P. ("Holdings III") is the sole member of each of BEMA NQ, BEP GP and BMA VI-NQ. The general partner of Holdings III is Blackstone Holdings III GP L.P. ("Holdings III GP"). The general partner of Holdings III GP is Blackstone Holdings III GP Management L.L.C ("Holdings III GP Management"). Blackstone Holdings II L.P. ("Holdings II") is the sole member of BCP GP. Blackstone Holdings I/II GP L.L.C. ("Holdings I/II GP") is the general partner of Holdings II. Blackstone Inc. ("Blackstone") is the sole member of Holdings III GP Management and Holdings I/II GP. The sole holder of the Series II preferred stock of Blackstone is Blackstone Group Management L.L.C. ("BS Group Management"). BS Group Management is wholly-owned by Blackstone's senior managing directors and controlled by its founder, Stephen A. Schwarzman.

F11 · ownership.nature: Information with respect to each of the Reporting Persons is given solely by such Reporting Person, and no Reporting Person has responsibility for the accuracy or completeness of information supplied by another Reporting Person.

F12 · ownership.nature: Due to the limitations of the electronic filing system certain Reporting Persons are filing a separate Form 4.

F13 · ownership.nature: Each of the Reporting Persons (other than to the extent it directly holds securities reported herein) disclaims beneficial ownership of the securities held by the other Reporting Persons, except to the extent of such Reporting Person's pecuniary interest therein, and, pursuant to Rule 16a-1(a)(4) under the Securities Exchange Act of 1934 (the "Exchange Act"), each of the Reporting Persons (other than to the extent it directly holds securities reported herein) states that the inclusion of these securities in this report shall not be deemed an admission of beneficial ownership of all of the securities reported herein for purposes of Section 16 of the Exchange Act or for any other purpose or that the Reporting Persons are subject to Section 16 of the Exchange Act.

SEC source: 0000899243-21-045646 · doc4.xml · nonDerivative · entry 3

Blackstone Energy Partners NQ L.P. · CIK 0001855931 · 10% owner

BEP CTOS Holdings L.P. · CIK 0001857352 · 10% owner

Blackstone Energy Family Investment Partnership SMD L.P. · CIK 0001851447 · 10% owner

Blackstone Energy Family Investment Partnership NQ ESC L.P. · CIK 0001855942 · 10% owner

Blackstone Capital Partners VI-NQ L.P. · CIK 0001855944 · 10% owner

BCP CTOS Holdings L.P. · CIK 0001857351 · 10% owner

Blackstone Family Investment Partnership VI-NQ ESC L.P. · CIK 0001856558 · 10% owner

Blackstone Energy Management Associates NQ L.L.C. · CIK 0001855939 · 10% owner

Blackstone EMA-NQ L.L.C. · CIK 0001855943 · 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: 45,860

F1 · price: This amount represents the $8.5000 public offering price per share of common stock, par value $0.0001 per share ("Common Stock"), of Custom Truck One Source, Inc. (the "Issuer"), less the underwriting discount of $0.02975 per share. The Underwriters have not yet exercised their Over-allotment Option to purchase additional shares of Common Stock.

F4 · ownership.nature: Reflects shares of Common Stock directly held by Blackstone Energy Family Investment Partnership SMD L.P. ("BE SMD").

F9 · ownership.nature: Blackstone Energy Management Associates NQ L.L.C. ("BEMA") is the general partner of BEP NQ and BEP CTOS. Blackstone EMA-NQ L.L.C. ("BEMA NQ") is the managing member of BEMA. BEP Side-by-Side GP NQ L.L.C. ("BEP GP") is the general partner of BE NQ. Blackstone Management Associates VI-NQ L.L.C. ("BMA NQ") is the general partner of BCP VI-NQ and BCP CTOS. BMA VI-NQ L.L.C. ("BMA VI-NQ") is the managing member of BMA NQ. Blackstone Family GP L.L.C. ("BS GP") is the general partner of BE SMD. BS GP is wholly-owned by Blackstone's senior managing directors and controlled by its founder, Stephen A. Schwarzman. BCP VI-NQ Side-by-Side GP L.L.C. ("BCP GP") is the general partner of BE FIP.

F10 · ownership.nature: Blackstone Holdings III L.P. ("Holdings III") is the sole member of each of BEMA NQ, BEP GP and BMA VI-NQ. The general partner of Holdings III is Blackstone Holdings III GP L.P. ("Holdings III GP"). The general partner of Holdings III GP is Blackstone Holdings III GP Management L.L.C ("Holdings III GP Management"). Blackstone Holdings II L.P. ("Holdings II") is the sole member of BCP GP. Blackstone Holdings I/II GP L.L.C. ("Holdings I/II GP") is the general partner of Holdings II. Blackstone Inc. ("Blackstone") is the sole member of Holdings III GP Management and Holdings I/II GP. The sole holder of the Series II preferred stock of Blackstone is Blackstone Group Management L.L.C. ("BS Group Management"). BS Group Management is wholly-owned by Blackstone's senior managing directors and controlled by its founder, Stephen A. Schwarzman.

F11 · ownership.nature: Information with respect to each of the Reporting Persons is given solely by such Reporting Person, and no Reporting Person has responsibility for the accuracy or completeness of information supplied by another Reporting Person.

F12 · ownership.nature: Due to the limitations of the electronic filing system certain Reporting Persons are filing a separate Form 4.

F13 · ownership.nature: Each of the Reporting Persons (other than to the extent it directly holds securities reported herein) disclaims beneficial ownership of the securities held by the other Reporting Persons, except to the extent of such Reporting Person's pecuniary interest therein, and, pursuant to Rule 16a-1(a)(4) under the Securities Exchange Act of 1934 (the "Exchange Act"), each of the Reporting Persons (other than to the extent it directly holds securities reported herein) states that the inclusion of these securities in this report shall not be deemed an admission of beneficial ownership of all of the securities reported herein for purposes of Section 16 of the Exchange Act or for any other purpose or that the Reporting Persons are subject to Section 16 of the Exchange Act.

SEC source: 0000899243-21-045646 · doc4.xml · nonDerivative · entry 2

Blackstone Energy Partners NQ L.P. · CIK 0001855931 · 10% owner

BEP CTOS Holdings L.P. · CIK 0001857352 · 10% owner

Blackstone Energy Family Investment Partnership SMD L.P. · CIK 0001851447 · 10% owner

Blackstone Energy Family Investment Partnership NQ ESC L.P. · CIK 0001855942 · 10% owner

Blackstone Capital Partners VI-NQ L.P. · CIK 0001855944 · 10% owner

BCP CTOS Holdings L.P. · CIK 0001857351 · 10% owner

Blackstone Family Investment Partnership VI-NQ ESC L.P. · CIK 0001856558 · 10% owner

Blackstone Energy Management Associates NQ L.L.C. · CIK 0001855939 · 10% owner

Blackstone EMA-NQ L.L.C. · CIK 0001855943 · 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: 472,446

F1 · price: This amount represents the $8.5000 public offering price per share of common stock, par value $0.0001 per share ("Common Stock"), of Custom Truck One Source, Inc. (the "Issuer"), less the underwriting discount of $0.02975 per share. The Underwriters have not yet exercised their Over-allotment Option to purchase additional shares of Common Stock.

F3 · ownership.nature: Reflects shares of Common Stock directly held by BEP CTOS Holdings L.P. ("BEP CTOS").

F9 · ownership.nature: Blackstone Energy Management Associates NQ L.L.C. ("BEMA") is the general partner of BEP NQ and BEP CTOS. Blackstone EMA-NQ L.L.C. ("BEMA NQ") is the managing member of BEMA. BEP Side-by-Side GP NQ L.L.C. ("BEP GP") is the general partner of BE NQ. Blackstone Management Associates VI-NQ L.L.C. ("BMA NQ") is the general partner of BCP VI-NQ and BCP CTOS. BMA VI-NQ L.L.C. ("BMA VI-NQ") is the managing member of BMA NQ. Blackstone Family GP L.L.C. ("BS GP") is the general partner of BE SMD. BS GP is wholly-owned by Blackstone's senior managing directors and controlled by its founder, Stephen A. Schwarzman. BCP VI-NQ Side-by-Side GP L.L.C. ("BCP GP") is the general partner of BE FIP.

F10 · ownership.nature: Blackstone Holdings III L.P. ("Holdings III") is the sole member of each of BEMA NQ, BEP GP and BMA VI-NQ. The general partner of Holdings III is Blackstone Holdings III GP L.P. ("Holdings III GP"). The general partner of Holdings III GP is Blackstone Holdings III GP Management L.L.C ("Holdings III GP Management"). Blackstone Holdings II L.P. ("Holdings II") is the sole member of BCP GP. Blackstone Holdings I/II GP L.L.C. ("Holdings I/II GP") is the general partner of Holdings II. Blackstone Inc. ("Blackstone") is the sole member of Holdings III GP Management and Holdings I/II GP. The sole holder of the Series II preferred stock of Blackstone is Blackstone Group Management L.L.C. ("BS Group Management"). BS Group Management is wholly-owned by Blackstone's senior managing directors and controlled by its founder, Stephen A. Schwarzman.

F11 · ownership.nature: Information with respect to each of the Reporting Persons is given solely by such Reporting Person, and no Reporting Person has responsibility for the accuracy or completeness of information supplied by another Reporting Person.

F12 · ownership.nature: Due to the limitations of the electronic filing system certain Reporting Persons are filing a separate Form 4.

F13 · ownership.nature: Each of the Reporting Persons (other than to the extent it directly holds securities reported herein) disclaims beneficial ownership of the securities held by the other Reporting Persons, except to the extent of such Reporting Person's pecuniary interest therein, and, pursuant to Rule 16a-1(a)(4) under the Securities Exchange Act of 1934 (the "Exchange Act"), each of the Reporting Persons (other than to the extent it directly holds securities reported herein) states that the inclusion of these securities in this report shall not be deemed an admission of beneficial ownership of all of the securities reported herein for purposes of Section 16 of the Exchange Act or for any other purpose or that the Reporting Persons are subject to Section 16 of the Exchange Act.

SEC source: 0000899243-21-045646 · doc4.xml · nonDerivative · entry 1

Blackstone Energy Partners NQ L.P. · CIK 0001855931 · 10% owner

BEP CTOS Holdings L.P. · CIK 0001857352 · 10% owner

Blackstone Energy Family Investment Partnership SMD L.P. · CIK 0001851447 · 10% owner

Blackstone Energy Family Investment Partnership NQ ESC L.P. · CIK 0001855942 · 10% owner

Blackstone Capital Partners VI-NQ L.P. · CIK 0001855944 · 10% owner

BCP CTOS Holdings L.P. · CIK 0001857351 · 10% owner

Blackstone Family Investment Partnership VI-NQ ESC L.P. · CIK 0001856558 · 10% owner

Blackstone Energy Management Associates NQ L.L.C. · CIK 0001855939 · 10% owner

Blackstone EMA-NQ L.L.C. · CIK 0001855943 · 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: 382,460

F1 · price: This amount represents the $8.5000 public offering price per share of common stock, par value $0.0001 per share ("Common Stock"), of Custom Truck One Source, Inc. (the "Issuer"), less the underwriting discount of $0.02975 per share. The Underwriters have not yet exercised their Over-allotment Option to purchase additional shares of Common Stock.

F2 · ownership.nature: Reflects shares of Common Stock directly held by Blackstone Energy Partners NQ L.P. ("BEP NQ").

F9 · ownership.nature: Blackstone Energy Management Associates NQ L.L.C. ("BEMA") is the general partner of BEP NQ and BEP CTOS. Blackstone EMA-NQ L.L.C. ("BEMA NQ") is the managing member of BEMA. BEP Side-by-Side GP NQ L.L.C. ("BEP GP") is the general partner of BE NQ. Blackstone Management Associates VI-NQ L.L.C. ("BMA NQ") is the general partner of BCP VI-NQ and BCP CTOS. BMA VI-NQ L.L.C. ("BMA VI-NQ") is the managing member of BMA NQ. Blackstone Family GP L.L.C. ("BS GP") is the general partner of BE SMD. BS GP is wholly-owned by Blackstone's senior managing directors and controlled by its founder, Stephen A. Schwarzman. BCP VI-NQ Side-by-Side GP L.L.C. ("BCP GP") is the general partner of BE FIP.

F10 · ownership.nature: Blackstone Holdings III L.P. ("Holdings III") is the sole member of each of BEMA NQ, BEP GP and BMA VI-NQ. The general partner of Holdings III is Blackstone Holdings III GP L.P. ("Holdings III GP"). The general partner of Holdings III GP is Blackstone Holdings III GP Management L.L.C ("Holdings III GP Management"). Blackstone Holdings II L.P. ("Holdings II") is the sole member of BCP GP. Blackstone Holdings I/II GP L.L.C. ("Holdings I/II GP") is the general partner of Holdings II. Blackstone Inc. ("Blackstone") is the sole member of Holdings III GP Management and Holdings I/II GP. The sole holder of the Series II preferred stock of Blackstone is Blackstone Group Management L.L.C. ("BS Group Management"). BS Group Management is wholly-owned by Blackstone's senior managing directors and controlled by its founder, Stephen A. Schwarzman.

F11 · ownership.nature: Information with respect to each of the Reporting Persons is given solely by such Reporting Person, and no Reporting Person has responsibility for the accuracy or completeness of information supplied by another Reporting Person.

F12 · ownership.nature: Due to the limitations of the electronic filing system certain Reporting Persons are filing a separate Form 4.

F13 · ownership.nature: Each of the Reporting Persons (other than to the extent it directly holds securities reported herein) disclaims beneficial ownership of the securities held by the other Reporting Persons, except to the extent of such Reporting Person's pecuniary interest therein, and, pursuant to Rule 16a-1(a)(4) under the Securities Exchange Act of 1934 (the "Exchange Act"), each of the Reporting Persons (other than to the extent it directly holds securities reported herein) states that the inclusion of these securities in this report shall not be deemed an admission of beneficial ownership of all of the securities reported herein for purposes of Section 16 of the Exchange Act or for any other purpose or that the Reporting Persons are subject to Section 16 of the Exchange Act.

SEC source: 0000899243-21-045654 · doc4.xml · nonDerivative · entry 7

Blackstone Holdings II L.P. · CIK 0001484870 · 10% owner

BLACKSTONE FAMILY GP LLC · CIK 0001404964 · 10% owner

BEP Side-by-Side GP NQ L.L.C. · CIK 0001857354 · 10% owner

Blackstone Management Associates VI-NQ L.L.C. · CIK 0001855930 · 10% owner

BMA VI-NQ L.L.C. · CIK 0001855977 · 10% owner

Blackstone Holdings III GP L.P. · CIK 0001478809 · 10% owner

Blackstone Holdings III GP Management L.L.C. · CIK 0001478815 · 10% owner

BCP VI-NQ Side-by-Side GP L.L.C. · CIK 0001856561 · 10% owner

Blackstone Holdings I/II GP L.L.C. · CIK 0001464695 · 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: 2,264

F1 · price: This amount represents the $8.5000 public offering price per share of common stock, par value $0.0001 per share ("Common Stock"), of Custom Truck One Source, Inc. (the "Issuer"), less the underwriting discount of $0.02975 per share. The Underwriters have not yet exercised their Over-allotment Option to purchase additional shares of Common Stock.

F8 · ownership.nature: Reflects shares of Common Stock directly held by Blackstone Family Investment Partnership VI-NQ ESC L.P. ("BE FIP").

F9 · ownership.nature: Blackstone Energy Management Associates NQ L.L.C. ("BEMA") is the general partner of BEP NQ and BEP CTOS. Blackstone EMA-NQ L.L.C. ("BEMA NQ") is the managing member of BEMA. BEP Side-by-Side GP NQ L.L.C. ("BEP GP") is the general partner of BE NQ. Blackstone Management Associates VI-NQ L.L.C. ("BMA NQ") is the general partner of BCP VI-NQ and BCP CTOS. BMA VI-NQ L.L.C. ("BMA VI-NQ") is the managing member of BMA NQ. Blackstone Family GP L.L.C. ("BS GP") is the general partner of BE SMD. BS GP is wholly-owned by Blackstone's senior managing directors and controlled by its founder, Stephen A. Schwarzman. BCP VI-NQ Side-by-Side GP L.L.C. ("BCP GP") is the general partner of BE FIP.

F10 · ownership.nature: Blackstone Holdings III L.P. ("Holdings III") is the sole member of each of BEMA NQ, BEP GP and BMA VI-NQ. The general partner of Holdings III is Blackstone Holdings III GP L.P. ("Holdings III GP"). The general partner of Holdings III GP is Blackstone Holdings III GP Management L.L.C ("Holdings III GP Management"). Blackstone Holdings II L.P. ("Holdings II") is the sole member of BCP GP. Blackstone Holdings I/II GP L.L.C. ("Holdings I/II GP") is the general partner of Holdings II. Blackstone Inc. ("Blackstone") is the sole member of Holdings III GP Management and Holdings I/II GP. The sole holder of the Series II preferred stock of Blackstone is Blackstone Group Management L.L.C. ("BS Group Management"). BS Group Management is wholly-owned by Blackstone's senior managing directors and controlled by its founder, Stephen A. Schwarzman.

F11 · ownership.nature: Information with respect to each of the Reporting Persons is given solely by such Reporting Person, and no Reporting Person has responsibility for the accuracy or completeness of information supplied by another Reporting Person.

F12 · ownership.nature: Due to the limitations of the electronic filing system certain Reporting Persons are filing a separate Form 4.

F13 · ownership.nature: Each of the Reporting Persons (other than to the extent it directly holds securities reported herein) disclaims beneficial ownership of the securities held by the other Reporting Persons, except to the extent of such Reporting Person's pecuniary interest therein, and, pursuant to Rule 16a-1(a)(4) under the Securities Exchange Act of 1934 (the "Exchange Act"), each of the Reporting Persons (other than to the extent it directly holds securities reported herein) states that the inclusion of these securities in this report shall not be deemed an admission of beneficial ownership of all of the securities reported herein for purposes of Section 16 of the Exchange Act or for any other purpose or that the Reporting Persons are subject to Section 16 of the Exchange Act.

SEC source: 0000899243-21-045654 · doc4.xml · nonDerivative · entry 6

Blackstone Holdings II L.P. · CIK 0001484870 · 10% owner

BLACKSTONE FAMILY GP LLC · CIK 0001404964 · 10% owner

BEP Side-by-Side GP NQ L.L.C. · CIK 0001857354 · 10% owner

Blackstone Management Associates VI-NQ L.L.C. · CIK 0001855930 · 10% owner

BMA VI-NQ L.L.C. · CIK 0001855977 · 10% owner

Blackstone Holdings III GP L.P. · CIK 0001478809 · 10% owner

Blackstone Holdings III GP Management L.L.C. · CIK 0001478815 · 10% owner

BCP VI-NQ Side-by-Side GP L.L.C. · CIK 0001856561 · 10% owner

Blackstone Holdings I/II GP L.L.C. · CIK 0001464695 · 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: 466,472

F1 · price: This amount represents the $8.5000 public offering price per share of common stock, par value $0.0001 per share ("Common Stock"), of Custom Truck One Source, Inc. (the "Issuer"), less the underwriting discount of $0.02975 per share. The Underwriters have not yet exercised their Over-allotment Option to purchase additional shares of Common Stock.

F7 · ownership.nature: Reflects shares of Common Stock directly held by BCP CTOS Holdings L.P. ("BCP CTOS").

F9 · ownership.nature: Blackstone Energy Management Associates NQ L.L.C. ("BEMA") is the general partner of BEP NQ and BEP CTOS. Blackstone EMA-NQ L.L.C. ("BEMA NQ") is the managing member of BEMA. BEP Side-by-Side GP NQ L.L.C. ("BEP GP") is the general partner of BE NQ. Blackstone Management Associates VI-NQ L.L.C. ("BMA NQ") is the general partner of BCP VI-NQ and BCP CTOS. BMA VI-NQ L.L.C. ("BMA VI-NQ") is the managing member of BMA NQ. Blackstone Family GP L.L.C. ("BS GP") is the general partner of BE SMD. BS GP is wholly-owned by Blackstone's senior managing directors and controlled by its founder, Stephen A. Schwarzman. BCP VI-NQ Side-by-Side GP L.L.C. ("BCP GP") is the general partner of BE FIP.

F10 · ownership.nature: Blackstone Holdings III L.P. ("Holdings III") is the sole member of each of BEMA NQ, BEP GP and BMA VI-NQ. The general partner of Holdings III is Blackstone Holdings III GP L.P. ("Holdings III GP"). The general partner of Holdings III GP is Blackstone Holdings III GP Management L.L.C ("Holdings III GP Management"). Blackstone Holdings II L.P. ("Holdings II") is the sole member of BCP GP. Blackstone Holdings I/II GP L.L.C. ("Holdings I/II GP") is the general partner of Holdings II. Blackstone Inc. ("Blackstone") is the sole member of Holdings III GP Management and Holdings I/II GP. The sole holder of the Series II preferred stock of Blackstone is Blackstone Group Management L.L.C. ("BS Group Management"). BS Group Management is wholly-owned by Blackstone's senior managing directors and controlled by its founder, Stephen A. Schwarzman.

F11 · ownership.nature: Information with respect to each of the Reporting Persons is given solely by such Reporting Person, and no Reporting Person has responsibility for the accuracy or completeness of information supplied by another Reporting Person.

F12 · ownership.nature: Due to the limitations of the electronic filing system certain Reporting Persons are filing a separate Form 4.

F13 · ownership.nature: Each of the Reporting Persons (other than to the extent it directly holds securities reported herein) disclaims beneficial ownership of the securities held by the other Reporting Persons, except to the extent of such Reporting Person's pecuniary interest therein, and, pursuant to Rule 16a-1(a)(4) under the Securities Exchange Act of 1934 (the "Exchange Act"), each of the Reporting Persons (other than to the extent it directly holds securities reported herein) states that the inclusion of these securities in this report shall not be deemed an admission of beneficial ownership of all of the securities reported herein for purposes of Section 16 of the Exchange Act or for any other purpose or that the Reporting Persons are subject to Section 16 of the Exchange Act.

SEC source: 0000899243-21-045654 · doc4.xml · nonDerivative · entry 5

Blackstone Holdings II L.P. · CIK 0001484870 · 10% owner

BLACKSTONE FAMILY GP LLC · CIK 0001404964 · 10% owner

BEP Side-by-Side GP NQ L.L.C. · CIK 0001857354 · 10% owner

Blackstone Management Associates VI-NQ L.L.C. · CIK 0001855930 · 10% owner

BMA VI-NQ L.L.C. · CIK 0001855977 · 10% owner

Blackstone Holdings III GP L.P. · CIK 0001478809 · 10% owner

Blackstone Holdings III GP Management L.L.C. · CIK 0001478815 · 10% owner

BCP VI-NQ Side-by-Side GP L.L.C. · CIK 0001856561 · 10% owner

Blackstone Holdings I/II GP L.L.C. · CIK 0001464695 · 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: 455,487

F1 · price: This amount represents the $8.5000 public offering price per share of common stock, par value $0.0001 per share ("Common Stock"), of Custom Truck One Source, Inc. (the "Issuer"), less the underwriting discount of $0.02975 per share. The Underwriters have not yet exercised their Over-allotment Option to purchase additional shares of Common Stock.

F6 · ownership.nature: Reflects shares of Common Stock directly held by Blackstone Capital Partners VI-NQ L.P. ("BCP VI-NQ").

F9 · ownership.nature: Blackstone Energy Management Associates NQ L.L.C. ("BEMA") is the general partner of BEP NQ and BEP CTOS. Blackstone EMA-NQ L.L.C. ("BEMA NQ") is the managing member of BEMA. BEP Side-by-Side GP NQ L.L.C. ("BEP GP") is the general partner of BE NQ. Blackstone Management Associates VI-NQ L.L.C. ("BMA NQ") is the general partner of BCP VI-NQ and BCP CTOS. BMA VI-NQ L.L.C. ("BMA VI-NQ") is the managing member of BMA NQ. Blackstone Family GP L.L.C. ("BS GP") is the general partner of BE SMD. BS GP is wholly-owned by Blackstone's senior managing directors and controlled by its founder, Stephen A. Schwarzman. BCP VI-NQ Side-by-Side GP L.L.C. ("BCP GP") is the general partner of BE FIP.

F10 · ownership.nature: Blackstone Holdings III L.P. ("Holdings III") is the sole member of each of BEMA NQ, BEP GP and BMA VI-NQ. The general partner of Holdings III is Blackstone Holdings III GP L.P. ("Holdings III GP"). The general partner of Holdings III GP is Blackstone Holdings III GP Management L.L.C ("Holdings III GP Management"). Blackstone Holdings II L.P. ("Holdings II") is the sole member of BCP GP. Blackstone Holdings I/II GP L.L.C. ("Holdings I/II GP") is the general partner of Holdings II. Blackstone Inc. ("Blackstone") is the sole member of Holdings III GP Management and Holdings I/II GP. The sole holder of the Series II preferred stock of Blackstone is Blackstone Group Management L.L.C. ("BS Group Management"). BS Group Management is wholly-owned by Blackstone's senior managing directors and controlled by its founder, Stephen A. Schwarzman.

F11 · ownership.nature: Information with respect to each of the Reporting Persons is given solely by such Reporting Person, and no Reporting Person has responsibility for the accuracy or completeness of information supplied by another Reporting Person.

F12 · ownership.nature: Due to the limitations of the electronic filing system certain Reporting Persons are filing a separate Form 4.

F13 · ownership.nature: Each of the Reporting Persons (other than to the extent it directly holds securities reported herein) disclaims beneficial ownership of the securities held by the other Reporting Persons, except to the extent of such Reporting Person's pecuniary interest therein, and, pursuant to Rule 16a-1(a)(4) under the Securities Exchange Act of 1934 (the "Exchange Act"), each of the Reporting Persons (other than to the extent it directly holds securities reported herein) states that the inclusion of these securities in this report shall not be deemed an admission of beneficial ownership of all of the securities reported herein for purposes of Section 16 of the Exchange Act or for any other purpose or that the Reporting Persons are subject to Section 16 of the Exchange Act.

SEC source: 0000899243-21-045654 · doc4.xml · nonDerivative · entry 4

Blackstone Holdings II L.P. · CIK 0001484870 · 10% owner

BLACKSTONE FAMILY GP LLC · CIK 0001404964 · 10% owner

BEP Side-by-Side GP NQ L.L.C. · CIK 0001857354 · 10% owner

Blackstone Management Associates VI-NQ L.L.C. · CIK 0001855930 · 10% owner

BMA VI-NQ L.L.C. · CIK 0001855977 · 10% owner

Blackstone Holdings III GP L.P. · CIK 0001478809 · 10% owner

Blackstone Holdings III GP Management L.L.C. · CIK 0001478815 · 10% owner

BCP VI-NQ Side-by-Side GP L.L.C. · CIK 0001856561 · 10% owner

Blackstone Holdings I/II GP L.L.C. · CIK 0001464695 · 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: 23,457

F1 · price: This amount represents the $8.5000 public offering price per share of common stock, par value $0.0001 per share ("Common Stock"), of Custom Truck One Source, Inc. (the "Issuer"), less the underwriting discount of $0.02975 per share. The Underwriters have not yet exercised their Over-allotment Option to purchase additional shares of Common Stock.

F5 · ownership.nature: Reflects shares of Common Stock directly held by Blackstone Energy Family Investment Partnership NQ ESC L.P. ("BE NQ").

F9 · ownership.nature: Blackstone Energy Management Associates NQ L.L.C. ("BEMA") is the general partner of BEP NQ and BEP CTOS. Blackstone EMA-NQ L.L.C. ("BEMA NQ") is the managing member of BEMA. BEP Side-by-Side GP NQ L.L.C. ("BEP GP") is the general partner of BE NQ. Blackstone Management Associates VI-NQ L.L.C. ("BMA NQ") is the general partner of BCP VI-NQ and BCP CTOS. BMA VI-NQ L.L.C. ("BMA VI-NQ") is the managing member of BMA NQ. Blackstone Family GP L.L.C. ("BS GP") is the general partner of BE SMD. BS GP is wholly-owned by Blackstone's senior managing directors and controlled by its founder, Stephen A. Schwarzman. BCP VI-NQ Side-by-Side GP L.L.C. ("BCP GP") is the general partner of BE FIP.

F10 · ownership.nature: Blackstone Holdings III L.P. ("Holdings III") is the sole member of each of BEMA NQ, BEP GP and BMA VI-NQ. The general partner of Holdings III is Blackstone Holdings III GP L.P. ("Holdings III GP"). The general partner of Holdings III GP is Blackstone Holdings III GP Management L.L.C ("Holdings III GP Management"). Blackstone Holdings II L.P. ("Holdings II") is the sole member of BCP GP. Blackstone Holdings I/II GP L.L.C. ("Holdings I/II GP") is the general partner of Holdings II. Blackstone Inc. ("Blackstone") is the sole member of Holdings III GP Management and Holdings I/II GP. The sole holder of the Series II preferred stock of Blackstone is Blackstone Group Management L.L.C. ("BS Group Management"). BS Group Management is wholly-owned by Blackstone's senior managing directors and controlled by its founder, Stephen A. Schwarzman.

F11 · ownership.nature: Information with respect to each of the Reporting Persons is given solely by such Reporting Person, and no Reporting Person has responsibility for the accuracy or completeness of information supplied by another Reporting Person.

F12 · ownership.nature: Due to the limitations of the electronic filing system certain Reporting Persons are filing a separate Form 4.

F13 · ownership.nature: Each of the Reporting Persons (other than to the extent it directly holds securities reported herein) disclaims beneficial ownership of the securities held by the other Reporting Persons, except to the extent of such Reporting Person's pecuniary interest therein, and, pursuant to Rule 16a-1(a)(4) under the Securities Exchange Act of 1934 (the "Exchange Act"), each of the Reporting Persons (other than to the extent it directly holds securities reported herein) states that the inclusion of these securities in this report shall not be deemed an admission of beneficial ownership of all of the securities reported herein for purposes of Section 16 of the Exchange Act or for any other purpose or that the Reporting Persons are subject to Section 16 of the Exchange Act.

SEC source: 0000899243-21-045654 · doc4.xml · nonDerivative · entry 3

Blackstone Holdings II L.P. · CIK 0001484870 · 10% owner

BLACKSTONE FAMILY GP LLC · CIK 0001404964 · 10% owner

BEP Side-by-Side GP NQ L.L.C. · CIK 0001857354 · 10% owner

Blackstone Management Associates VI-NQ L.L.C. · CIK 0001855930 · 10% owner

BMA VI-NQ L.L.C. · CIK 0001855977 · 10% owner

Blackstone Holdings III GP L.P. · CIK 0001478809 · 10% owner

Blackstone Holdings III GP Management L.L.C. · CIK 0001478815 · 10% owner

BCP VI-NQ Side-by-Side GP L.L.C. · CIK 0001856561 · 10% owner

Blackstone Holdings I/II GP L.L.C. · CIK 0001464695 · 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: 45,860

F1 · price: This amount represents the $8.5000 public offering price per share of common stock, par value $0.0001 per share ("Common Stock"), of Custom Truck One Source, Inc. (the "Issuer"), less the underwriting discount of $0.02975 per share. The Underwriters have not yet exercised their Over-allotment Option to purchase additional shares of Common Stock.

F4 · ownership.nature: Reflects shares of Common Stock directly held by Blackstone Energy Family Investment Partnership SMD L.P. ("BE SMD").

F9 · ownership.nature: Blackstone Energy Management Associates NQ L.L.C. ("BEMA") is the general partner of BEP NQ and BEP CTOS. Blackstone EMA-NQ L.L.C. ("BEMA NQ") is the managing member of BEMA. BEP Side-by-Side GP NQ L.L.C. ("BEP GP") is the general partner of BE NQ. Blackstone Management Associates VI-NQ L.L.C. ("BMA NQ") is the general partner of BCP VI-NQ and BCP CTOS. BMA VI-NQ L.L.C. ("BMA VI-NQ") is the managing member of BMA NQ. Blackstone Family GP L.L.C. ("BS GP") is the general partner of BE SMD. BS GP is wholly-owned by Blackstone's senior managing directors and controlled by its founder, Stephen A. Schwarzman. BCP VI-NQ Side-by-Side GP L.L.C. ("BCP GP") is the general partner of BE FIP.

F10 · ownership.nature: Blackstone Holdings III L.P. ("Holdings III") is the sole member of each of BEMA NQ, BEP GP and BMA VI-NQ. The general partner of Holdings III is Blackstone Holdings III GP L.P. ("Holdings III GP"). The general partner of Holdings III GP is Blackstone Holdings III GP Management L.L.C ("Holdings III GP Management"). Blackstone Holdings II L.P. ("Holdings II") is the sole member of BCP GP. Blackstone Holdings I/II GP L.L.C. ("Holdings I/II GP") is the general partner of Holdings II. Blackstone Inc. ("Blackstone") is the sole member of Holdings III GP Management and Holdings I/II GP. The sole holder of the Series II preferred stock of Blackstone is Blackstone Group Management L.L.C. ("BS Group Management"). BS Group Management is wholly-owned by Blackstone's senior managing directors and controlled by its founder, Stephen A. Schwarzman.

F11 · ownership.nature: Information with respect to each of the Reporting Persons is given solely by such Reporting Person, and no Reporting Person has responsibility for the accuracy or completeness of information supplied by another Reporting Person.

F12 · ownership.nature: Due to the limitations of the electronic filing system certain Reporting Persons are filing a separate Form 4.

F13 · ownership.nature: Each of the Reporting Persons (other than to the extent it directly holds securities reported herein) disclaims beneficial ownership of the securities held by the other Reporting Persons, except to the extent of such Reporting Person's pecuniary interest therein, and, pursuant to Rule 16a-1(a)(4) under the Securities Exchange Act of 1934 (the "Exchange Act"), each of the Reporting Persons (other than to the extent it directly holds securities reported herein) states that the inclusion of these securities in this report shall not be deemed an admission of beneficial ownership of all of the securities reported herein for purposes of Section 16 of the Exchange Act or for any other purpose or that the Reporting Persons are subject to Section 16 of the Exchange Act.

SEC source: 0000899243-21-045654 · doc4.xml · nonDerivative · entry 2

Blackstone Holdings II L.P. · CIK 0001484870 · 10% owner

BLACKSTONE FAMILY GP LLC · CIK 0001404964 · 10% owner

BEP Side-by-Side GP NQ L.L.C. · CIK 0001857354 · 10% owner

Blackstone Management Associates VI-NQ L.L.C. · CIK 0001855930 · 10% owner

BMA VI-NQ L.L.C. · CIK 0001855977 · 10% owner

Blackstone Holdings III GP L.P. · CIK 0001478809 · 10% owner

Blackstone Holdings III GP Management L.L.C. · CIK 0001478815 · 10% owner

BCP VI-NQ Side-by-Side GP L.L.C. · CIK 0001856561 · 10% owner

Blackstone Holdings I/II GP L.L.C. · CIK 0001464695 · 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: 472,446

F1 · price: This amount represents the $8.5000 public offering price per share of common stock, par value $0.0001 per share ("Common Stock"), of Custom Truck One Source, Inc. (the "Issuer"), less the underwriting discount of $0.02975 per share. The Underwriters have not yet exercised their Over-allotment Option to purchase additional shares of Common Stock.

F3 · ownership.nature: Reflects shares of Common Stock directly held by BEP CTOS Holdings L.P. ("BEP CTOS").

F9 · ownership.nature: Blackstone Energy Management Associates NQ L.L.C. ("BEMA") is the general partner of BEP NQ and BEP CTOS. Blackstone EMA-NQ L.L.C. ("BEMA NQ") is the managing member of BEMA. BEP Side-by-Side GP NQ L.L.C. ("BEP GP") is the general partner of BE NQ. Blackstone Management Associates VI-NQ L.L.C. ("BMA NQ") is the general partner of BCP VI-NQ and BCP CTOS. BMA VI-NQ L.L.C. ("BMA VI-NQ") is the managing member of BMA NQ. Blackstone Family GP L.L.C. ("BS GP") is the general partner of BE SMD. BS GP is wholly-owned by Blackstone's senior managing directors and controlled by its founder, Stephen A. Schwarzman. BCP VI-NQ Side-by-Side GP L.L.C. ("BCP GP") is the general partner of BE FIP.

F10 · ownership.nature: Blackstone Holdings III L.P. ("Holdings III") is the sole member of each of BEMA NQ, BEP GP and BMA VI-NQ. The general partner of Holdings III is Blackstone Holdings III GP L.P. ("Holdings III GP"). The general partner of Holdings III GP is Blackstone Holdings III GP Management L.L.C ("Holdings III GP Management"). Blackstone Holdings II L.P. ("Holdings II") is the sole member of BCP GP. Blackstone Holdings I/II GP L.L.C. ("Holdings I/II GP") is the general partner of Holdings II. Blackstone Inc. ("Blackstone") is the sole member of Holdings III GP Management and Holdings I/II GP. The sole holder of the Series II preferred stock of Blackstone is Blackstone Group Management L.L.C. ("BS Group Management"). BS Group Management is wholly-owned by Blackstone's senior managing directors and controlled by its founder, Stephen A. Schwarzman.

F11 · ownership.nature: Information with respect to each of the Reporting Persons is given solely by such Reporting Person, and no Reporting Person has responsibility for the accuracy or completeness of information supplied by another Reporting Person.

F12 · ownership.nature: Due to the limitations of the electronic filing system certain Reporting Persons are filing a separate Form 4.

F13 · ownership.nature: Each of the Reporting Persons (other than to the extent it directly holds securities reported herein) disclaims beneficial ownership of the securities held by the other Reporting Persons, except to the extent of such Reporting Person's pecuniary interest therein, and, pursuant to Rule 16a-1(a)(4) under the Securities Exchange Act of 1934 (the "Exchange Act"), each of the Reporting Persons (other than to the extent it directly holds securities reported herein) states that the inclusion of these securities in this report shall not be deemed an admission of beneficial ownership of all of the securities reported herein for purposes of Section 16 of the Exchange Act or for any other purpose or that the Reporting Persons are subject to Section 16 of the Exchange Act.

SEC source: 0000899243-21-045654 · doc4.xml · nonDerivative · entry 1

Blackstone Holdings II L.P. · CIK 0001484870 · 10% owner

BLACKSTONE FAMILY GP LLC · CIK 0001404964 · 10% owner

BEP Side-by-Side GP NQ L.L.C. · CIK 0001857354 · 10% owner

Blackstone Management Associates VI-NQ L.L.C. · CIK 0001855930 · 10% owner

BMA VI-NQ L.L.C. · CIK 0001855977 · 10% owner

Blackstone Holdings III GP L.P. · CIK 0001478809 · 10% owner

Blackstone Holdings III GP Management L.L.C. · CIK 0001478815 · 10% owner

BCP VI-NQ Side-by-Side GP L.L.C. · CIK 0001856561 · 10% owner

Blackstone Holdings I/II GP L.L.C. · CIK 0001464695 · 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: 382,460

F1 · price: This amount represents the $8.5000 public offering price per share of common stock, par value $0.0001 per share ("Common Stock"), of Custom Truck One Source, Inc. (the "Issuer"), less the underwriting discount of $0.02975 per share. The Underwriters have not yet exercised their Over-allotment Option to purchase additional shares of Common Stock.

F2 · ownership.nature: Reflects shares of Common Stock directly held by Blackstone Energy Partners NQ L.P. ("BEP NQ").

F9 · ownership.nature: Blackstone Energy Management Associates NQ L.L.C. ("BEMA") is the general partner of BEP NQ and BEP CTOS. Blackstone EMA-NQ L.L.C. ("BEMA NQ") is the managing member of BEMA. BEP Side-by-Side GP NQ L.L.C. ("BEP GP") is the general partner of BE NQ. Blackstone Management Associates VI-NQ L.L.C. ("BMA NQ") is the general partner of BCP VI-NQ and BCP CTOS. BMA VI-NQ L.L.C. ("BMA VI-NQ") is the managing member of BMA NQ. Blackstone Family GP L.L.C. ("BS GP") is the general partner of BE SMD. BS GP is wholly-owned by Blackstone's senior managing directors and controlled by its founder, Stephen A. Schwarzman. BCP VI-NQ Side-by-Side GP L.L.C. ("BCP GP") is the general partner of BE FIP.

F10 · ownership.nature: Blackstone Holdings III L.P. ("Holdings III") is the sole member of each of BEMA NQ, BEP GP and BMA VI-NQ. The general partner of Holdings III is Blackstone Holdings III GP L.P. ("Holdings III GP"). The general partner of Holdings III GP is Blackstone Holdings III GP Management L.L.C ("Holdings III GP Management"). Blackstone Holdings II L.P. ("Holdings II") is the sole member of BCP GP. Blackstone Holdings I/II GP L.L.C. ("Holdings I/II GP") is the general partner of Holdings II. Blackstone Inc. ("Blackstone") is the sole member of Holdings III GP Management and Holdings I/II GP. The sole holder of the Series II preferred stock of Blackstone is Blackstone Group Management L.L.C. ("BS Group Management"). BS Group Management is wholly-owned by Blackstone's senior managing directors and controlled by its founder, Stephen A. Schwarzman.

F11 · ownership.nature: Information with respect to each of the Reporting Persons is given solely by such Reporting Person, and no Reporting Person has responsibility for the accuracy or completeness of information supplied by another Reporting Person.

F12 · ownership.nature: Due to the limitations of the electronic filing system certain Reporting Persons are filing a separate Form 4.

F13 · ownership.nature: Each of the Reporting Persons (other than to the extent it directly holds securities reported herein) disclaims beneficial ownership of the securities held by the other Reporting Persons, except to the extent of such Reporting Person's pecuniary interest therein, and, pursuant to Rule 16a-1(a)(4) under the Securities Exchange Act of 1934 (the "Exchange Act"), each of the Reporting Persons (other than to the extent it directly holds securities reported herein) states that the inclusion of these securities in this report shall not be deemed an admission of beneficial ownership of all of the securities reported herein for purposes of Section 16 of the Exchange Act or for any other purpose or that the Reporting Persons are subject to Section 16 of the Exchange Act.

SEC source: 0000899243-21-045659 · doc4.xml · nonDerivative · entry 7

Blackstone Holdings III L.P. · CIK 0001404073 · 10% owner

Blackstone Inc · CIK 0001393818 · 10% owner

Blackstone Group Management L.L.C. · CIK 0001404071 · 10% owner

SCHWARZMAN STEPHEN A · CIK 0001070844 · 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: 2,264

F1 · price: This amount represents the $8.5000 public offering price per share of common stock, par value $0.0001 per share ("Common Stock"), of Custom Truck One Source, Inc. (the "Issuer"), less the underwriting discount of $0.02975 per share. The Underwriters have not yet exercised their Over-allotment Option to purchase additional shares of Common Stock.

F8 · ownership.nature: Reflects shares of Common Stock directly held by Blackstone Family Investment Partnership VI-NQ ESC L.P. ("BE FIP").

F9 · ownership.nature: Blackstone Energy Management Associates NQ L.L.C. ("BEMA") is the general partner of BEP NQ and BEP CTOS. Blackstone EMA-NQ L.L.C. ("BEMA NQ") is the managing member of BEMA. BEP Side-by-Side GP NQ L.L.C. ("BEP GP") is the general partner of BE NQ. Blackstone Management Associates VI-NQ L.L.C. ("BMA NQ") is the general partner of BCP VI-NQ and BCP CTOS. BMA VI-NQ L.L.C. ("BMA VI-NQ") is the managing member of BMA NQ. Blackstone Family GP L.L.C. ("BS GP") is the general partner of BE SMD. BS GP is wholly-owned by Blackstone's senior managing directors and controlled by its founder, Stephen A. Schwarzman. BCP VI-NQ Side-by-Side GP L.L.C. ("BCP GP") is the general partner of BE FIP.

F10 · ownership.nature: Blackstone Holdings III L.P. ("Holdings III") is the sole member of each of BEMA NQ, BEP GP and BMA VI-NQ. The general partner of Holdings III is Blackstone Holdings III GP L.P. ("Holdings III GP"). The general partner of Holdings III GP is Blackstone Holdings III GP Management L.L.C ("Holdings III GP Management"). Blackstone Holdings II L.P. ("Holdings II") is the sole member of BCP GP. Blackstone Holdings I/II GP L.L.C. ("Holdings I/II GP") is the general partner of Holdings II. Blackstone Inc. ("Blackstone") is the sole member of Holdings III GP Management and Holdings I/II GP. The sole holder of the Series II preferred stock of Blackstone is Blackstone Group Management L.L.C. ("BS Group Management"). BS Group Management is wholly-owned by Blackstone's senior managing directors and controlled by its founder, Stephen A. Schwarzman.

F11 · ownership.nature: Information with respect to each of the Reporting Persons is given solely by such Reporting Person, and no Reporting Person has responsibility for the accuracy or completeness of information supplied by another Reporting Person.

F12 · ownership.nature: Due to the limitations of the electronic filing system certain Reporting Persons are filing a separate Form 4.

F13 · ownership.nature: Each of the Reporting Persons (other than to the extent it directly holds securities reported herein) disclaims beneficial ownership of the securities held by the other Reporting Persons, except to the extent of such Reporting Person's pecuniary interest therein, and, pursuant to Rule 16a-1(a)(4) under the Securities Exchange Act of 1934 (the "Exchange Act"), each of the Reporting Persons (other than to the extent it directly holds securities reported herein) states that the inclusion of these securities in this report shall not be deemed an admission of beneficial ownership of all of the securities reported herein for purposes of Section 16 of the Exchange Act or for any other purpose or that the Reporting Persons are subject to Section 16 of the Exchange Act.

SEC source: 0000899243-21-045659 · doc4.xml · nonDerivative · entry 6

Blackstone Holdings III L.P. · CIK 0001404073 · 10% owner

Blackstone Inc · CIK 0001393818 · 10% owner

Blackstone Group Management L.L.C. · CIK 0001404071 · 10% owner

SCHWARZMAN STEPHEN A · CIK 0001070844 · 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: 466,472

F1 · price: This amount represents the $8.5000 public offering price per share of common stock, par value $0.0001 per share ("Common Stock"), of Custom Truck One Source, Inc. (the "Issuer"), less the underwriting discount of $0.02975 per share. The Underwriters have not yet exercised their Over-allotment Option to purchase additional shares of Common Stock.

F7 · ownership.nature: Reflects shares of Common Stock directly held by BCP CTOS Holdings L.P. ("BCP CTOS").

F9 · ownership.nature: Blackstone Energy Management Associates NQ L.L.C. ("BEMA") is the general partner of BEP NQ and BEP CTOS. Blackstone EMA-NQ L.L.C. ("BEMA NQ") is the managing member of BEMA. BEP Side-by-Side GP NQ L.L.C. ("BEP GP") is the general partner of BE NQ. Blackstone Management Associates VI-NQ L.L.C. ("BMA NQ") is the general partner of BCP VI-NQ and BCP CTOS. BMA VI-NQ L.L.C. ("BMA VI-NQ") is the managing member of BMA NQ. Blackstone Family GP L.L.C. ("BS GP") is the general partner of BE SMD. BS GP is wholly-owned by Blackstone's senior managing directors and controlled by its founder, Stephen A. Schwarzman. BCP VI-NQ Side-by-Side GP L.L.C. ("BCP GP") is the general partner of BE FIP.

F10 · ownership.nature: Blackstone Holdings III L.P. ("Holdings III") is the sole member of each of BEMA NQ, BEP GP and BMA VI-NQ. The general partner of Holdings III is Blackstone Holdings III GP L.P. ("Holdings III GP"). The general partner of Holdings III GP is Blackstone Holdings III GP Management L.L.C ("Holdings III GP Management"). Blackstone Holdings II L.P. ("Holdings II") is the sole member of BCP GP. Blackstone Holdings I/II GP L.L.C. ("Holdings I/II GP") is the general partner of Holdings II. Blackstone Inc. ("Blackstone") is the sole member of Holdings III GP Management and Holdings I/II GP. The sole holder of the Series II preferred stock of Blackstone is Blackstone Group Management L.L.C. ("BS Group Management"). BS Group Management is wholly-owned by Blackstone's senior managing directors and controlled by its founder, Stephen A. Schwarzman.

F11 · ownership.nature: Information with respect to each of the Reporting Persons is given solely by such Reporting Person, and no Reporting Person has responsibility for the accuracy or completeness of information supplied by another Reporting Person.

F12 · ownership.nature: Due to the limitations of the electronic filing system certain Reporting Persons are filing a separate Form 4.

F13 · ownership.nature: Each of the Reporting Persons (other than to the extent it directly holds securities reported herein) disclaims beneficial ownership of the securities held by the other Reporting Persons, except to the extent of such Reporting Person's pecuniary interest therein, and, pursuant to Rule 16a-1(a)(4) under the Securities Exchange Act of 1934 (the "Exchange Act"), each of the Reporting Persons (other than to the extent it directly holds securities reported herein) states that the inclusion of these securities in this report shall not be deemed an admission of beneficial ownership of all of the securities reported herein for purposes of Section 16 of the Exchange Act or for any other purpose or that the Reporting Persons are subject to Section 16 of the Exchange Act.

SEC source: 0000899243-21-045659 · doc4.xml · nonDerivative · entry 5

Blackstone Holdings III L.P. · CIK 0001404073 · 10% owner

Blackstone Inc · CIK 0001393818 · 10% owner

Blackstone Group Management L.L.C. · CIK 0001404071 · 10% owner

SCHWARZMAN STEPHEN A · CIK 0001070844 · 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: 455,487

F1 · price: This amount represents the $8.5000 public offering price per share of common stock, par value $0.0001 per share ("Common Stock"), of Custom Truck One Source, Inc. (the "Issuer"), less the underwriting discount of $0.02975 per share. The Underwriters have not yet exercised their Over-allotment Option to purchase additional shares of Common Stock.

F6 · ownership.nature: Reflects shares of Common Stock directly held by Blackstone Capital Partners VI-NQ L.P. ("BCP VI-NQ").

F9 · ownership.nature: Blackstone Energy Management Associates NQ L.L.C. ("BEMA") is the general partner of BEP NQ and BEP CTOS. Blackstone EMA-NQ L.L.C. ("BEMA NQ") is the managing member of BEMA. BEP Side-by-Side GP NQ L.L.C. ("BEP GP") is the general partner of BE NQ. Blackstone Management Associates VI-NQ L.L.C. ("BMA NQ") is the general partner of BCP VI-NQ and BCP CTOS. BMA VI-NQ L.L.C. ("BMA VI-NQ") is the managing member of BMA NQ. Blackstone Family GP L.L.C. ("BS GP") is the general partner of BE SMD. BS GP is wholly-owned by Blackstone's senior managing directors and controlled by its founder, Stephen A. Schwarzman. BCP VI-NQ Side-by-Side GP L.L.C. ("BCP GP") is the general partner of BE FIP.

F10 · ownership.nature: Blackstone Holdings III L.P. ("Holdings III") is the sole member of each of BEMA NQ, BEP GP and BMA VI-NQ. The general partner of Holdings III is Blackstone Holdings III GP L.P. ("Holdings III GP"). The general partner of Holdings III GP is Blackstone Holdings III GP Management L.L.C ("Holdings III GP Management"). Blackstone Holdings II L.P. ("Holdings II") is the sole member of BCP GP. Blackstone Holdings I/II GP L.L.C. ("Holdings I/II GP") is the general partner of Holdings II. Blackstone Inc. ("Blackstone") is the sole member of Holdings III GP Management and Holdings I/II GP. The sole holder of the Series II preferred stock of Blackstone is Blackstone Group Management L.L.C. ("BS Group Management"). BS Group Management is wholly-owned by Blackstone's senior managing directors and controlled by its founder, Stephen A. Schwarzman.

F11 · ownership.nature: Information with respect to each of the Reporting Persons is given solely by such Reporting Person, and no Reporting Person has responsibility for the accuracy or completeness of information supplied by another Reporting Person.

F12 · ownership.nature: Due to the limitations of the electronic filing system certain Reporting Persons are filing a separate Form 4.

F13 · ownership.nature: Each of the Reporting Persons (other than to the extent it directly holds securities reported herein) disclaims beneficial ownership of the securities held by the other Reporting Persons, except to the extent of such Reporting Person's pecuniary interest therein, and, pursuant to Rule 16a-1(a)(4) under the Securities Exchange Act of 1934 (the "Exchange Act"), each of the Reporting Persons (other than to the extent it directly holds securities reported herein) states that the inclusion of these securities in this report shall not be deemed an admission of beneficial ownership of all of the securities reported herein for purposes of Section 16 of the Exchange Act or for any other purpose or that the Reporting Persons are subject to Section 16 of the Exchange Act.

SEC source: 0000899243-21-045659 · doc4.xml · nonDerivative · entry 4

Blackstone Holdings III L.P. · CIK 0001404073 · 10% owner

Blackstone Inc · CIK 0001393818 · 10% owner

Blackstone Group Management L.L.C. · CIK 0001404071 · 10% owner

SCHWARZMAN STEPHEN A · CIK 0001070844 · 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: 23,457

F1 · price: This amount represents the $8.5000 public offering price per share of common stock, par value $0.0001 per share ("Common Stock"), of Custom Truck One Source, Inc. (the "Issuer"), less the underwriting discount of $0.02975 per share. The Underwriters have not yet exercised their Over-allotment Option to purchase additional shares of Common Stock.

F5 · ownership.nature: Reflects shares of Common Stock directly held by Blackstone Energy Family Investment Partnership NQ ESC L.P. ("BE NQ").

F9 · ownership.nature: Blackstone Energy Management Associates NQ L.L.C. ("BEMA") is the general partner of BEP NQ and BEP CTOS. Blackstone EMA-NQ L.L.C. ("BEMA NQ") is the managing member of BEMA. BEP Side-by-Side GP NQ L.L.C. ("BEP GP") is the general partner of BE NQ. Blackstone Management Associates VI-NQ L.L.C. ("BMA NQ") is the general partner of BCP VI-NQ and BCP CTOS. BMA VI-NQ L.L.C. ("BMA VI-NQ") is the managing member of BMA NQ. Blackstone Family GP L.L.C. ("BS GP") is the general partner of BE SMD. BS GP is wholly-owned by Blackstone's senior managing directors and controlled by its founder, Stephen A. Schwarzman. BCP VI-NQ Side-by-Side GP L.L.C. ("BCP GP") is the general partner of BE FIP.

F10 · ownership.nature: Blackstone Holdings III L.P. ("Holdings III") is the sole member of each of BEMA NQ, BEP GP and BMA VI-NQ. The general partner of Holdings III is Blackstone Holdings III GP L.P. ("Holdings III GP"). The general partner of Holdings III GP is Blackstone Holdings III GP Management L.L.C ("Holdings III GP Management"). Blackstone Holdings II L.P. ("Holdings II") is the sole member of BCP GP. Blackstone Holdings I/II GP L.L.C. ("Holdings I/II GP") is the general partner of Holdings II. Blackstone Inc. ("Blackstone") is the sole member of Holdings III GP Management and Holdings I/II GP. The sole holder of the Series II preferred stock of Blackstone is Blackstone Group Management L.L.C. ("BS Group Management"). BS Group Management is wholly-owned by Blackstone's senior managing directors and controlled by its founder, Stephen A. Schwarzman.

F11 · ownership.nature: Information with respect to each of the Reporting Persons is given solely by such Reporting Person, and no Reporting Person has responsibility for the accuracy or completeness of information supplied by another Reporting Person.

F12 · ownership.nature: Due to the limitations of the electronic filing system certain Reporting Persons are filing a separate Form 4.

F13 · ownership.nature: Each of the Reporting Persons (other than to the extent it directly holds securities reported herein) disclaims beneficial ownership of the securities held by the other Reporting Persons, except to the extent of such Reporting Person's pecuniary interest therein, and, pursuant to Rule 16a-1(a)(4) under the Securities Exchange Act of 1934 (the "Exchange Act"), each of the Reporting Persons (other than to the extent it directly holds securities reported herein) states that the inclusion of these securities in this report shall not be deemed an admission of beneficial ownership of all of the securities reported herein for purposes of Section 16 of the Exchange Act or for any other purpose or that the Reporting Persons are subject to Section 16 of the Exchange Act.

SEC source: 0000899243-21-045659 · doc4.xml · nonDerivative · entry 3

Blackstone Holdings III L.P. · CIK 0001404073 · 10% owner

Blackstone Inc · CIK 0001393818 · 10% owner

Blackstone Group Management L.L.C. · CIK 0001404071 · 10% owner

SCHWARZMAN STEPHEN A · CIK 0001070844 · 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: 45,860

F1 · price: This amount represents the $8.5000 public offering price per share of common stock, par value $0.0001 per share ("Common Stock"), of Custom Truck One Source, Inc. (the "Issuer"), less the underwriting discount of $0.02975 per share. The Underwriters have not yet exercised their Over-allotment Option to purchase additional shares of Common Stock.

F4 · ownership.nature: Reflects shares of Common Stock directly held by Blackstone Energy Family Investment Partnership SMD L.P. ("BE SMD").

F9 · ownership.nature: Blackstone Energy Management Associates NQ L.L.C. ("BEMA") is the general partner of BEP NQ and BEP CTOS. Blackstone EMA-NQ L.L.C. ("BEMA NQ") is the managing member of BEMA. BEP Side-by-Side GP NQ L.L.C. ("BEP GP") is the general partner of BE NQ. Blackstone Management Associates VI-NQ L.L.C. ("BMA NQ") is the general partner of BCP VI-NQ and BCP CTOS. BMA VI-NQ L.L.C. ("BMA VI-NQ") is the managing member of BMA NQ. Blackstone Family GP L.L.C. ("BS GP") is the general partner of BE SMD. BS GP is wholly-owned by Blackstone's senior managing directors and controlled by its founder, Stephen A. Schwarzman. BCP VI-NQ Side-by-Side GP L.L.C. ("BCP GP") is the general partner of BE FIP.

F10 · ownership.nature: Blackstone Holdings III L.P. ("Holdings III") is the sole member of each of BEMA NQ, BEP GP and BMA VI-NQ. The general partner of Holdings III is Blackstone Holdings III GP L.P. ("Holdings III GP"). The general partner of Holdings III GP is Blackstone Holdings III GP Management L.L.C ("Holdings III GP Management"). Blackstone Holdings II L.P. ("Holdings II") is the sole member of BCP GP. Blackstone Holdings I/II GP L.L.C. ("Holdings I/II GP") is the general partner of Holdings II. Blackstone Inc. ("Blackstone") is the sole member of Holdings III GP Management and Holdings I/II GP. The sole holder of the Series II preferred stock of Blackstone is Blackstone Group Management L.L.C. ("BS Group Management"). BS Group Management is wholly-owned by Blackstone's senior managing directors and controlled by its founder, Stephen A. Schwarzman.

F11 · ownership.nature: Information with respect to each of the Reporting Persons is given solely by such Reporting Person, and no Reporting Person has responsibility for the accuracy or completeness of information supplied by another Reporting Person.

F12 · ownership.nature: Due to the limitations of the electronic filing system certain Reporting Persons are filing a separate Form 4.

F13 · ownership.nature: Each of the Reporting Persons (other than to the extent it directly holds securities reported herein) disclaims beneficial ownership of the securities held by the other Reporting Persons, except to the extent of such Reporting Person's pecuniary interest therein, and, pursuant to Rule 16a-1(a)(4) under the Securities Exchange Act of 1934 (the "Exchange Act"), each of the Reporting Persons (other than to the extent it directly holds securities reported herein) states that the inclusion of these securities in this report shall not be deemed an admission of beneficial ownership of all of the securities reported herein for purposes of Section 16 of the Exchange Act or for any other purpose or that the Reporting Persons are subject to Section 16 of the Exchange Act.

SEC source: 0000899243-21-045659 · doc4.xml · nonDerivative · entry 2

Blackstone Holdings III L.P. · CIK 0001404073 · 10% owner

Blackstone Inc · CIK 0001393818 · 10% owner

Blackstone Group Management L.L.C. · CIK 0001404071 · 10% owner

SCHWARZMAN STEPHEN A · CIK 0001070844 · 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: 472,446

F1 · price: This amount represents the $8.5000 public offering price per share of common stock, par value $0.0001 per share ("Common Stock"), of Custom Truck One Source, Inc. (the "Issuer"), less the underwriting discount of $0.02975 per share. The Underwriters have not yet exercised their Over-allotment Option to purchase additional shares of Common Stock.

F3 · ownership.nature: Reflects shares of Common Stock directly held by BEP CTOS Holdings L.P. ("BEP CTOS").

F9 · ownership.nature: Blackstone Energy Management Associates NQ L.L.C. ("BEMA") is the general partner of BEP NQ and BEP CTOS. Blackstone EMA-NQ L.L.C. ("BEMA NQ") is the managing member of BEMA. BEP Side-by-Side GP NQ L.L.C. ("BEP GP") is the general partner of BE NQ. Blackstone Management Associates VI-NQ L.L.C. ("BMA NQ") is the general partner of BCP VI-NQ and BCP CTOS. BMA VI-NQ L.L.C. ("BMA VI-NQ") is the managing member of BMA NQ. Blackstone Family GP L.L.C. ("BS GP") is the general partner of BE SMD. BS GP is wholly-owned by Blackstone's senior managing directors and controlled by its founder, Stephen A. Schwarzman. BCP VI-NQ Side-by-Side GP L.L.C. ("BCP GP") is the general partner of BE FIP.

F10 · ownership.nature: Blackstone Holdings III L.P. ("Holdings III") is the sole member of each of BEMA NQ, BEP GP and BMA VI-NQ. The general partner of Holdings III is Blackstone Holdings III GP L.P. ("Holdings III GP"). The general partner of Holdings III GP is Blackstone Holdings III GP Management L.L.C ("Holdings III GP Management"). Blackstone Holdings II L.P. ("Holdings II") is the sole member of BCP GP. Blackstone Holdings I/II GP L.L.C. ("Holdings I/II GP") is the general partner of Holdings II. Blackstone Inc. ("Blackstone") is the sole member of Holdings III GP Management and Holdings I/II GP. The sole holder of the Series II preferred stock of Blackstone is Blackstone Group Management L.L.C. ("BS Group Management"). BS Group Management is wholly-owned by Blackstone's senior managing directors and controlled by its founder, Stephen A. Schwarzman.

F11 · ownership.nature: Information with respect to each of the Reporting Persons is given solely by such Reporting Person, and no Reporting Person has responsibility for the accuracy or completeness of information supplied by another Reporting Person.

F12 · ownership.nature: Due to the limitations of the electronic filing system certain Reporting Persons are filing a separate Form 4.

F13 · ownership.nature: Each of the Reporting Persons (other than to the extent it directly holds securities reported herein) disclaims beneficial ownership of the securities held by the other Reporting Persons, except to the extent of such Reporting Person's pecuniary interest therein, and, pursuant to Rule 16a-1(a)(4) under the Securities Exchange Act of 1934 (the "Exchange Act"), each of the Reporting Persons (other than to the extent it directly holds securities reported herein) states that the inclusion of these securities in this report shall not be deemed an admission of beneficial ownership of all of the securities reported herein for purposes of Section 16 of the Exchange Act or for any other purpose or that the Reporting Persons are subject to Section 16 of the Exchange Act.

SEC source: 0000899243-21-045659 · doc4.xml · nonDerivative · entry 1

Blackstone Holdings III L.P. · CIK 0001404073 · 10% owner

Blackstone Inc · CIK 0001393818 · 10% owner

Blackstone Group Management L.L.C. · CIK 0001404071 · 10% owner

SCHWARZMAN STEPHEN A · CIK 0001070844 · 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: 382,460

F1 · price: This amount represents the $8.5000 public offering price per share of common stock, par value $0.0001 per share ("Common Stock"), of Custom Truck One Source, Inc. (the "Issuer"), less the underwriting discount of $0.02975 per share. The Underwriters have not yet exercised their Over-allotment Option to purchase additional shares of Common Stock.

F2 · ownership.nature: Reflects shares of Common Stock directly held by Blackstone Energy Partners NQ L.P. ("BEP NQ").

F9 · ownership.nature: Blackstone Energy Management Associates NQ L.L.C. ("BEMA") is the general partner of BEP NQ and BEP CTOS. Blackstone EMA-NQ L.L.C. ("BEMA NQ") is the managing member of BEMA. BEP Side-by-Side GP NQ L.L.C. ("BEP GP") is the general partner of BE NQ. Blackstone Management Associates VI-NQ L.L.C. ("BMA NQ") is the general partner of BCP VI-NQ and BCP CTOS. BMA VI-NQ L.L.C. ("BMA VI-NQ") is the managing member of BMA NQ. Blackstone Family GP L.L.C. ("BS GP") is the general partner of BE SMD. BS GP is wholly-owned by Blackstone's senior managing directors and controlled by its founder, Stephen A. Schwarzman. BCP VI-NQ Side-by-Side GP L.L.C. ("BCP GP") is the general partner of BE FIP.

F10 · ownership.nature: Blackstone Holdings III L.P. ("Holdings III") is the sole member of each of BEMA NQ, BEP GP and BMA VI-NQ. The general partner of Holdings III is Blackstone Holdings III GP L.P. ("Holdings III GP"). The general partner of Holdings III GP is Blackstone Holdings III GP Management L.L.C ("Holdings III GP Management"). Blackstone Holdings II L.P. ("Holdings II") is the sole member of BCP GP. Blackstone Holdings I/II GP L.L.C. ("Holdings I/II GP") is the general partner of Holdings II. Blackstone Inc. ("Blackstone") is the sole member of Holdings III GP Management and Holdings I/II GP. The sole holder of the Series II preferred stock of Blackstone is Blackstone Group Management L.L.C. ("BS Group Management"). BS Group Management is wholly-owned by Blackstone's senior managing directors and controlled by its founder, Stephen A. Schwarzman.

F11 · ownership.nature: Information with respect to each of the Reporting Persons is given solely by such Reporting Person, and no Reporting Person has responsibility for the accuracy or completeness of information supplied by another Reporting Person.

F12 · ownership.nature: Due to the limitations of the electronic filing system certain Reporting Persons are filing a separate Form 4.

F13 · ownership.nature: Each of the Reporting Persons (other than to the extent it directly holds securities reported herein) disclaims beneficial ownership of the securities held by the other Reporting Persons, except to the extent of such Reporting Person's pecuniary interest therein, and, pursuant to Rule 16a-1(a)(4) under the Securities Exchange Act of 1934 (the "Exchange Act"), each of the Reporting Persons (other than to the extent it directly holds securities reported herein) states that the inclusion of these securities in this report shall not be deemed an admission of beneficial ownership of all of the securities reported herein for purposes of Section 16 of the Exchange Act or for any other purpose or that the Reporting Persons are subject to Section 16 of the Exchange Act.

SEC source: 0001213900-21-043700 · ownership.xml · nonDerivative · entry 1

McMonagle Ryan · CIK 0001851380 · President, COO

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 205,000

F1 · price: The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $6.61 to $6.66, inclusive. The reporting person undertakes to provide to the Company, any security holder of the Company, 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 the footnote to this Form.

SEC source: 0001213900-21-043697 · ownership.xml · nonDerivative · entry 2

Heinberg Marshall · CIK 0001481338 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · By Domestic Partner

Disclosed balance after: 65,000

F2 · price: The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $6.35 to $6.65, inclusive.

SEC source: 0001213900-21-043697 · ownership.xml · nonDerivative · entry 1

Heinberg Marshall · CIK 0001481338 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 115,000

F1 · price: The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $6.35 to $6.65, inclusive. The reporting person undertakes to provide to the Company, any security holder of the Company, 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 footnotes (1) and (2) to this Form.

SEC source: 0001213900-21-036546 · ownership.xml · derivative · entry 2

McMonagle Ryan · CIK 0001851380 · President, COO

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 162,500

Underlying: Common Stock · 162,500 shares

Expires not disclosed

F3 · derivative.exercise_price: Each performance stock unit represents a contingent right to receive one share of the Issuer's common stock. The performance stock units will vest if the volume weighted average price per share of the Issuer's common stock achieves certain thresholds over the performance period ending December 31, 2024.

F3 · derivative.exercise_date: Each performance stock unit represents a contingent right to receive one share of the Issuer's common stock. The performance stock units will vest if the volume weighted average price per share of the Issuer's common stock achieves certain thresholds over the performance period ending December 31, 2024.

F3 · derivative.expiration_date: Each performance stock unit represents a contingent right to receive one share of the Issuer's common stock. The performance stock units will vest if the volume weighted average price per share of the Issuer's common stock achieves certain thresholds over the performance period ending December 31, 2024.

SEC source: 0001213900-21-036546 · ownership.xml · derivative · entry 1

McMonagle Ryan · CIK 0001851380 · President, COO

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 162,500

Underlying: Common Stock · 162,500 shares

Expires not disclosed

F1 · derivative.exercise_price: Each restricted stock unit represents a contingent right to receive one share of the Issuer's common stock.

F2 · derivative.exercise_date: The restricted stock units vest in four equal annual installments beginning on April 1, 2022.

F2 · derivative.expiration_date: The restricted stock units vest in four equal annual installments beginning on April 1, 2022.

SEC source: 0001213900-21-036550 · ownership.xml · derivative · entry 2

Rich Thomas R. · CIK 0001854514 · EVP - Rentals

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 100,000

Underlying: Common Stock · 100,000 shares

Expires not disclosed

F3 · derivative.exercise_price: Each performance stock unit represents a contingent right to receive one share of the Issuer's common stock. The performance stock units will vest if the volume weighted average price per share of the Issuer's common stock achieves certain thresholds over the performance period ending December 31, 2024.

F3 · derivative.exercise_date: Each performance stock unit represents a contingent right to receive one share of the Issuer's common stock. The performance stock units will vest if the volume weighted average price per share of the Issuer's common stock achieves certain thresholds over the performance period ending December 31, 2024.

F3 · derivative.expiration_date: Each performance stock unit represents a contingent right to receive one share of the Issuer's common stock. The performance stock units will vest if the volume weighted average price per share of the Issuer's common stock achieves certain thresholds over the performance period ending December 31, 2024.

SEC source: 0001213900-21-036550 · ownership.xml · derivative · entry 1

Rich Thomas R. · CIK 0001854514 · EVP - Rentals

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 100,000

Underlying: Common Stock · 100,000 shares

Expires not disclosed

F1 · derivative.exercise_price: Each restricted stock unit represents a contingent right to receive one share of the Issuer's common stock.

F2 · derivative.exercise_date: The restricted stock units vest in four equal annual installments beginning on April 1, 2022.

F2 · derivative.expiration_date: The restricted stock units vest in four equal annual installments beginning on April 1, 2022.

SEC source: 0001213900-21-036543 · ownership.xml · derivative · entry 2

Carlsen James · CIK 0001854934 · CIO

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 17,500

Underlying: Common Stock · 17,500 shares

Expires not disclosed

F3 · derivative.exercise_price: Each performance stock unit represents a contingent right to receive one share of the Issuer's common stock. The performance stock units will vest if the volume weighted average price per share of the Issuer's common stock achieves certain thresholds over the performance period ending December 31, 2024.

F3 · derivative.exercise_date: Each performance stock unit represents a contingent right to receive one share of the Issuer's common stock. The performance stock units will vest if the volume weighted average price per share of the Issuer's common stock achieves certain thresholds over the performance period ending December 31, 2024.

F3 · derivative.expiration_date: Each performance stock unit represents a contingent right to receive one share of the Issuer's common stock. The performance stock units will vest if the volume weighted average price per share of the Issuer's common stock achieves certain thresholds over the performance period ending December 31, 2024.

SEC source: 0001213900-21-036543 · ownership.xml · derivative · entry 1

Carlsen James · CIK 0001854934 · CIO

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 17,500

Underlying: Common Stock · 17,500 shares

Expires not disclosed

F1 · derivative.exercise_price: Each restricted stock unit represents a contingent right to receive one share of the Issuer's common stock.

F2 · derivative.exercise_date: The restricted stock units vest in four equal annual installments beginning on April 1, 2022.

F2 · derivative.expiration_date: The restricted stock units vest in four equal annual installments beginning on April 1, 2022.

SEC source: 0001213900-21-036536 · ownership.xml · derivative · entry 2

Haubenreich Adam G. · CIK 0001852510 · VP and General Counsel

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 62,500

Underlying: Common Stock · 62,500 shares

Expires not disclosed

F3 · derivative.exercise_price: Each performance stock unit represents a contingent right to receive one share of the Issuer's common stock. The performance stock units will vest if the volume weighted average price per share of the Issuer's common stock achieves certain thresholds over the performance period ending December 31, 2024.

F3 · derivative.exercise_date: Each performance stock unit represents a contingent right to receive one share of the Issuer's common stock. The performance stock units will vest if the volume weighted average price per share of the Issuer's common stock achieves certain thresholds over the performance period ending December 31, 2024.

F3 · derivative.expiration_date: Each performance stock unit represents a contingent right to receive one share of the Issuer's common stock. The performance stock units will vest if the volume weighted average price per share of the Issuer's common stock achieves certain thresholds over the performance period ending December 31, 2024.

SEC source: 0001213900-21-036536 · ownership.xml · derivative · entry 1

Haubenreich Adam G. · CIK 0001852510 · VP and General Counsel

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 62,500

Underlying: Common Stock · 62,500 shares

Expires not disclosed

F1 · derivative.exercise_price: Each restricted stock unit represents a contingent right to receive one share of the Issuer's common stock.

F2 · derivative.exercise_date: The restricted stock units vest in four equal annual installments beginning on April 1, 2022.

F2 · derivative.expiration_date: The restricted stock units vest in four equal annual installments beginning on April 1, 2022.

SEC source: 0001213900-21-036544 · ownership.xml · derivative · entry 2

Ross Joe P. · CIK 0001852519 · President - Sales

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 100,000

Underlying: Common Stock · 100,000 shares

Expires not disclosed

F3 · derivative.exercise_price: Each performance stock unit represents a contingent right to receive one share of the Issuer's common stock. The performance stock units will vest if the volume weighted average price per share of the Issuer's common stock achieves certain thresholds over the performance period ending December 31, 2024.

F3 · derivative.exercise_date: Each performance stock unit represents a contingent right to receive one share of the Issuer's common stock. The performance stock units will vest if the volume weighted average price per share of the Issuer's common stock achieves certain thresholds over the performance period ending December 31, 2024.

F3 · derivative.expiration_date: Each performance stock unit represents a contingent right to receive one share of the Issuer's common stock. The performance stock units will vest if the volume weighted average price per share of the Issuer's common stock achieves certain thresholds over the performance period ending December 31, 2024.

SEC source: 0001213900-21-036544 · ownership.xml · derivative · entry 1

Ross Joe P. · CIK 0001852519 · President - Sales

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 100,000

Underlying: Common Stock · 100,000 shares

Expires not disclosed

F1 · derivative.exercise_price: Each restricted stock unit represents a contingent right to receive one share of the Issuer's common stock.

F2 · derivative.exercise_date: The restricted stock units vest in four equal annual installments beginning on April 1, 2022.

F2 · derivative.expiration_date: The restricted stock units vest in four equal annual installments beginning on April 1, 2022.

SEC source: 0001213900-21-036538 · ownership.xml · derivative · entry 2

Meader Brad · CIK 0001852169 · Chief Financial Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 75,000

Underlying: Common Stock · 75,000 shares

Expires not disclosed

F3 · derivative.exercise_price: Each performance stock unit represents a contingent right to receive one share of the Issuer's common stock. The performance stock units will vest if the volume weighted average price per share of the Issuer's common stock achieves certain thresholds over the performance period ending December 31, 2024.

F3 · derivative.exercise_date: Each performance stock unit represents a contingent right to receive one share of the Issuer's common stock. The performance stock units will vest if the volume weighted average price per share of the Issuer's common stock achieves certain thresholds over the performance period ending December 31, 2024.

F3 · derivative.expiration_date: Each performance stock unit represents a contingent right to receive one share of the Issuer's common stock. The performance stock units will vest if the volume weighted average price per share of the Issuer's common stock achieves certain thresholds over the performance period ending December 31, 2024.

SEC source: 0001213900-21-036538 · ownership.xml · derivative · entry 1

Meader Brad · CIK 0001852169 · Chief Financial Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 75,000

Underlying: Common Stock · 75,000 shares

Expires not disclosed

F1 · derivative.exercise_price: Each restricted stock unit represents a contingent right to receive one share of the Issuer's common stock.

F2 · derivative.exercise_date: The restricted stock units vest in four equal annual installments beginning on April 1, 2022.

F2 · derivative.expiration_date: The restricted stock units vest in four equal annual installments beginning on April 1, 2022.

SEC source: 0001213900-21-036540 · ownership.xml · derivative · entry 2

Ross Fredrick M. Jr. · CIK 0001851369 · Director · Chief Executive Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 175,000

Underlying: Common Stock · 175,000 shares

Expires not disclosed

F3 · derivative.exercise_price: Each performance stock unit represents a contingent right to receive one share of the Issuer's common stock. The performance stock units will vest if the volume weighted average price per share of the Issuer's common stock achieves certain thresholds over the performance period ending December 31, 2024.

F3 · derivative.exercise_date: Each performance stock unit represents a contingent right to receive one share of the Issuer's common stock. The performance stock units will vest if the volume weighted average price per share of the Issuer's common stock achieves certain thresholds over the performance period ending December 31, 2024.

F3 · derivative.expiration_date: Each performance stock unit represents a contingent right to receive one share of the Issuer's common stock. The performance stock units will vest if the volume weighted average price per share of the Issuer's common stock achieves certain thresholds over the performance period ending December 31, 2024.

SEC source: 0001213900-21-036540 · ownership.xml · derivative · entry 1

Ross Fredrick M. Jr. · CIK 0001851369 · Director · Chief Executive Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 175,000

Underlying: Common Stock · 175,000 shares

Expires not disclosed

F1 · derivative.exercise_price: Each restricted stock unit represents a contingent right to receive one share of the Issuer's common stock.

F2 · derivative.exercise_date: The restricted stock units vest in four equal annual installments beginning on April 1, 2022.

F2 · derivative.expiration_date: The restricted stock units vest in four equal annual installments beginning on April 1, 2022.

SEC source: 0001213900-21-036548 · ownership.xml · derivative · entry 2

BARRETT RAYMOND TODD · CIK 0001785100 · Chief Accounting Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 17,500

Underlying: Common Stock · 17,500 shares

Expires not disclosed

F3 · derivative.exercise_price: Each performance stock unit represents a contingent right to receive one share of the Issuer's common stock. The performance stock units will vest if the volume weighted average price per share of the Issuer's common stock achieves certain thresholds over the performance period ending December 31, 2024.

F3 · derivative.exercise_date: Each performance stock unit represents a contingent right to receive one share of the Issuer's common stock. The performance stock units will vest if the volume weighted average price per share of the Issuer's common stock achieves certain thresholds over the performance period ending December 31, 2024.

F3 · derivative.expiration_date: Each performance stock unit represents a contingent right to receive one share of the Issuer's common stock. The performance stock units will vest if the volume weighted average price per share of the Issuer's common stock achieves certain thresholds over the performance period ending December 31, 2024.

SEC source: 0001213900-21-036548 · ownership.xml · derivative · entry 1

BARRETT RAYMOND TODD · CIK 0001785100 · Chief Accounting Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 17,500

Underlying: Common Stock · 17,500 shares

Expires not disclosed

F1 · derivative.exercise_price: Each restricted stock unit represents a contingent right to receive one share of the Issuer's common stock.

F2 · derivative.exercise_date: The restricted stock units vest in four equal annual installments beginning on April 1, 2022.

F2 · derivative.expiration_date: The restricted stock units vest in four equal annual installments beginning on April 1, 2022.

SEC source: 0001213900-21-029712 · ownership.xml · derivative · entry 2

McMonagle Ryan · CIK 0001851380 · President, COO

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 162,500

Underlying: Common Stock · 162,500 shares

Expires not disclosed

F3 · derivative.exercise_price: Each performance stock unit represents a contingent right to receive one share of the Issuer's common stock. The performance stock units will vest if the volume weighted average price per share of the Issuer's common stock achieves certain thresholds over the performance period ending December 31, 2024.

F3 · derivative.exercise_date: Each performance stock unit represents a contingent right to receive one share of the Issuer's common stock. The performance stock units will vest if the volume weighted average price per share of the Issuer's common stock achieves certain thresholds over the performance period ending December 31, 2024.

F3 · derivative.expiration_date: Each performance stock unit represents a contingent right to receive one share of the Issuer's common stock. The performance stock units will vest if the volume weighted average price per share of the Issuer's common stock achieves certain thresholds over the performance period ending December 31, 2024.