FULC

SEC source: 0000899243-20-002037 · doc4.xml · derivative · entry 3

Thomson Peter G. · CIK 0001779120 · VP Finance & Accounting

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 33,100

Underlying: Common Stock · 33,100 shares

Expires 2030-01-22

F4 · derivative.exercise_date: This option was granted on January 23, 2020 and is scheduled to vest in equal quarterly installments over four years beginning on the vesting commencement date of January 1, 2020, subject to continued service.

SEC source: 0000899243-20-002037 · doc4.xml · nonDerivative · entry 2

Thomson Peter G. · CIK 0001779120 · VP Finance & Accounting

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 33,571

F1 · kind: The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on December 9, 2019.

F3 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $17.98 to $18.26, inclusive. The reporting person undertakes to provide to Fulcrum Therapeutics, Inc., any security holder of Fulcrum Therapeutics, Inc. or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote (3) to this Form 4.

SEC source: 0000899243-20-002037 · doc4.xml · nonDerivative · entry 1

Thomson Peter G. · CIK 0001779120 · VP Finance & Accounting

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 33,833

F1 · kind: The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on December 9, 2019.

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $16.78 to $17.73, inclusive. The reporting person undertakes to provide to Fulcrum Therapeutics, Inc., any security holder of Fulcrum Therapeutics, Inc. or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote (2) to this Form 4.

SEC source: 0000899243-20-002035 · doc4.xml · derivative · entry 1

Gould Robert J · CIK 0001577034 · Director · President & CEO

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 200,000

Underlying: Common Stock · 200,000 shares

Expires 2030-01-22

F1 · derivative.exercise_date: This option was granted on January 23, 2020 and is scheduled to vest in equal quarterly installments over four years beginning on the vesting commencement date of January 1, 2020, subject to continued service.

SEC source: 0000899243-20-002040 · doc4.xml · derivative · entry 1

Cadavid Diego · CIK 0001778713 · SVP Clinical Development

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 55,440

Underlying: Common Stock · 55,440 shares

Expires 2030-01-22

F1 · derivative.exercise_date: This option was granted on January 23, 2020 and is scheduled to vest in equal quarterly installments over four years beginning on the vesting commencement date of January 1, 2020, subject to continued service.

SEC source: 0000899243-20-002041 · doc4.xml · derivative · entry 1

Stuart Bryan · CIK 0001619846 · Chief Operating Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 105,000

Underlying: Common Stock · 105,000 shares

Expires 2030-01-22

F1 · derivative.exercise_date: This option was granted on January 23, 2020 and is scheduled to vest in equal quarterly installments over four years beginning on the vesting commencement date of January 1, 2020, subject to continued service.

SEC source: 0000899243-20-002034 · doc4.xml · derivative · entry 1

Wallace Owen B. · CIK 0001778843 · Chief Scientific Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 58,900

Underlying: Common Stock · 58,900 shares

Expires 2030-01-22

F1 · derivative.exercise_date: This option was granted on January 23, 2020 and is scheduled to vest in equal quarterly installments over four years beginning on the vesting commencement date of January 1, 2020, subject to continued service.

SEC source: 0000899243-20-000462 · doc4.xml · derivative · entry 1

Dorton Katina · CIK 0001617541 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 18,571

Underlying: Common Stock · 18,571 shares

Expires 2030-01-01

F1 · derivative.exercise_date: This option was granted on January 2, 2020 and is scheduled to vest in equal monthly installments through January 2, 2023, subject to continued service.

SEC source: 0001104659-19-041304 · a4.xml · derivative · entry 3

LEVIN MARK J · CIK 0001180428 · Director · 10% owner

10b5-1 filing: Not disclosed

Ownership: Indirect · By fund

Disclosed balance after: 0

Underlying: Common Stock · 5,595,238 shares

Expires not disclosed

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

F1 · derivative.exercise_price: On July 22, 2019, the Series A Preferred Stock converted into Common Stock on a seven-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series A Preferred Stock was convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F1 · derivative.exercise_date: On July 22, 2019, the Series A Preferred Stock converted into Common Stock on a seven-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series A Preferred Stock was convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F1 · derivative.expiration_date: On July 22, 2019, the Series A Preferred Stock converted into Common Stock on a seven-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series A Preferred Stock was convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F2 · ownership.nature: The shares are directly held by Third Rock Ventures III, L.P. ("TRV III"). The general partner of TRV III is Third Rock Ventures GP III, L.P. ("TRV GP III LP"). The general partner of TRV GP III LP is TRV GP III, LLC ("TRV GP III LLC"). The individual managers of TRV GP III LLC are Mark Levin ("Levin"), Kevin Starr ("Starr") and Dr. Robert Tepper ("Tepper"). Each of TRV GP III LP, TRV GP III LLC, Levin, Starr and Tepper disclaims beneficial ownership of the shares except to the extent of its or his pecuniary interest therein, if any, and this report shall not be deemed an admission that it or he is the beneficial owner of such shares.

SEC source: 0001104659-19-041304 · a4.xml · nonDerivative · entry 2

LEVIN MARK J · CIK 0001180428 · Director · 10% owner

10b5-1 filing: Not disclosed

Ownership: Indirect · By fund

Disclosed balance after: 5,962,202

F2 · ownership.nature: The shares are directly held by Third Rock Ventures III, L.P. ("TRV III"). The general partner of TRV III is Third Rock Ventures GP III, L.P. ("TRV GP III LP"). The general partner of TRV GP III LP is TRV GP III, LLC ("TRV GP III LLC"). The individual managers of TRV GP III LLC are Mark Levin ("Levin"), Kevin Starr ("Starr") and Dr. Robert Tepper ("Tepper"). Each of TRV GP III LP, TRV GP III LLC, Levin, Starr and Tepper disclaims beneficial ownership of the shares except to the extent of its or his pecuniary interest therein, if any, and this report shall not be deemed an admission that it or he is the beneficial owner of such shares.

SEC source: 0001104659-19-041304 · a4.xml · nonDerivative · entry 1

LEVIN MARK J · CIK 0001180428 · Director · 10% owner

10b5-1 filing: Not disclosed

Ownership: Indirect · By fund

Disclosed balance after: 5,880,952

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

F1 · price: On July 22, 2019, the Series A Preferred Stock converted into Common Stock on a seven-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series A Preferred Stock was convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F2 · ownership.nature: The shares are directly held by Third Rock Ventures III, L.P. ("TRV III"). The general partner of TRV III is Third Rock Ventures GP III, L.P. ("TRV GP III LP"). The general partner of TRV GP III LP is TRV GP III, LLC ("TRV GP III LLC"). The individual managers of TRV GP III LLC are Mark Levin ("Levin"), Kevin Starr ("Starr") and Dr. Robert Tepper ("Tepper"). Each of TRV GP III LP, TRV GP III LLC, Levin, Starr and Tepper disclaims beneficial ownership of the shares except to the extent of its or his pecuniary interest therein, if any, and this report shall not be deemed an admission that it or he is the beneficial owner of such shares.

SEC source: 0001104659-19-041307 · a4.xml · derivative · entry 3

6 Dimensions Capital, L.P. · CIK 0001717958 · 10% owner

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 441,071 shares

Expires not disclosed

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

F1 · derivative.exercise_price: On July 22, 2019 the Series B Preferred Stock converted into Common Stock on 7:1 basis upon the closing of the issuer's initial public offering without payment of consideration. The shares had no expiration date.

F1 · derivative.exercise_date: On July 22, 2019 the Series B Preferred Stock converted into Common Stock on 7:1 basis upon the closing of the issuer's initial public offering without payment of consideration. The shares had no expiration date.

F1 · derivative.expiration_date: On July 22, 2019 the Series B Preferred Stock converted into Common Stock on 7:1 basis upon the closing of the issuer's initial public offering without payment of consideration. The shares had no expiration date.

SEC source: 0001104659-19-041307 · a4.xml · nonDerivative · entry 2

6 Dimensions Capital, L.P. · CIK 0001717958 · 10% owner

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 559,821

SEC source: 0001104659-19-041307 · a4.xml · nonDerivative · entry 1

6 Dimensions Capital, L.P. · CIK 0001717958 · 10% owner

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 441,071

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

F1 · price: On July 22, 2019 the Series B Preferred Stock converted into Common Stock on 7:1 basis upon the closing of the issuer's initial public offering without payment of consideration. The shares had no expiration date.

SEC source: 0000899243-19-020029 · doc4.xml · derivative · entry 3

Third Rock Ventures IV, L.P. · CIK 0001688327 · 10% owner

Third Rock Ventures GP IV, L.P. · CIK 0001688326 · 10% owner

TRV GP IV, LLC · CIK 0001688325 · 10% owner

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

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 2,261,904 shares

Expires not disclosed

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

F1 · derivative.exercise_price: On July 22, 2019, the Series A Preferred Stock converted into Common Stock on a seven-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series A Preferred Stock was convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial pubic offering. The shares had no expiration date.

F1 · derivative.exercise_date: On July 22, 2019, the Series A Preferred Stock converted into Common Stock on a seven-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series A Preferred Stock was convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial pubic offering. The shares had no expiration date.

F1 · derivative.expiration_date: On July 22, 2019, the Series A Preferred Stock converted into Common Stock on a seven-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series A Preferred Stock was convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial pubic offering. The shares had no expiration date.

F2 · ownership.direct: These shares are directly held by Third Rock Ventures IV, L.P. ("TRV IV"). The general partner of TRV IV is Third Rock Ventures GP IV, L.P. ("TRV GP IV"). The general partner of TRV GP IV is TRV GP IV, LLC ("TRV GP IV LLC"). Each of TRV GP IV and TRV GP IV LLC disclaims beneficial ownership of these shares except to the extent of its pecuniary interest therein, if any, and this report shall not be deemed an admission that it is the beneficial owner of such shares.

SEC source: 0000899243-19-020029 · doc4.xml · nonDerivative · entry 2

Third Rock Ventures IV, L.P. · CIK 0001688327 · 10% owner

Third Rock Ventures GP IV, L.P. · CIK 0001688326 · 10% owner

TRV GP IV, LLC · CIK 0001688325 · 10% owner

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

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 2,343,154

F2 · ownership.direct: These shares are directly held by Third Rock Ventures IV, L.P. ("TRV IV"). The general partner of TRV IV is Third Rock Ventures GP IV, L.P. ("TRV GP IV"). The general partner of TRV GP IV is TRV GP IV, LLC ("TRV GP IV LLC"). Each of TRV GP IV and TRV GP IV LLC disclaims beneficial ownership of these shares except to the extent of its pecuniary interest therein, if any, and this report shall not be deemed an admission that it is the beneficial owner of such shares.

SEC source: 0000899243-19-020029 · doc4.xml · nonDerivative · entry 1

Third Rock Ventures IV, L.P. · CIK 0001688327 · 10% owner

Third Rock Ventures GP IV, L.P. · CIK 0001688326 · 10% owner

TRV GP IV, LLC · CIK 0001688325 · 10% owner

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

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 2,261,904

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

F1 · price: On July 22, 2019, the Series A Preferred Stock converted into Common Stock on a seven-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series A Preferred Stock was convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial pubic offering. The shares had no expiration date.

F2 · ownership.direct: These shares are directly held by Third Rock Ventures IV, L.P. ("TRV IV"). The general partner of TRV IV is Third Rock Ventures GP IV, L.P. ("TRV GP IV"). The general partner of TRV GP IV is TRV GP IV, LLC ("TRV GP IV LLC"). Each of TRV GP IV and TRV GP IV LLC disclaims beneficial ownership of these shares except to the extent of its pecuniary interest therein, if any, and this report shall not be deemed an admission that it is the beneficial owner of such shares.

SEC source: 0000899243-19-020026 · doc4.xml · derivative · entry 4

Third Rock Ventures III, L.P. · CIK 0001569705 · 10% owner

Third Rock Ventures GP III, L.P. · CIK 0001637300 · 10% owner

TRV GP III, LLC · CIK 0001637299 · 10% owner

STARR KEVIN P · CIK 0001192603 · 10% owner

TEPPER ROBERT I · CIK 0001192595 · 10% owner

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

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 0 shares

Expires not disclosed

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

F3 · derivative.exercise_price: On July 22, 2019, the Series A Preferred Stock converted into Common Stock on a seven-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series A Preferred Stock was convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial pubic offering. The shares had no expiration date.

F2 · shares: As of the date of this filing, Third Rock Ventures IV, L.P. ("TRV IV") holds 2,261,904 shares of Common Stock issued upon conversion of 15,833,333 shares of Series A Preferred Stock. The general partner of TRV IV is Third Rock Ventures GP IV, L.P. ("TRV GP IV"). The general partner of TRV GP IV is TRV GP IV, LLC ("TRV GP IV LLC"). Abbie Celniker, Ph.D., Tepper, Alexis Borisy, Craig Muir and Cary Pfeffer, M.D. are the managing members of TRV IV LLC who collectively make voting and investment decisions with respect to shares held by TRV IV LP. Tepper disclaims beneficial ownership of the shares except to the extent of his pecuniary interest therein, if any, and this report shall not be deemed an admission that he is the beneficial owner of such shares.

F3 · derivative.exercise_date: On July 22, 2019, the Series A Preferred Stock converted into Common Stock on a seven-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series A Preferred Stock was convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial pubic offering. The shares had no expiration date.

F3 · derivative.expiration_date: On July 22, 2019, the Series A Preferred Stock converted into Common Stock on a seven-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series A Preferred Stock was convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial pubic offering. The shares had no expiration date.

F2 · derivative.underlying_shares: As of the date of this filing, Third Rock Ventures IV, L.P. ("TRV IV") holds 2,261,904 shares of Common Stock issued upon conversion of 15,833,333 shares of Series A Preferred Stock. The general partner of TRV IV is Third Rock Ventures GP IV, L.P. ("TRV GP IV"). The general partner of TRV GP IV is TRV GP IV, LLC ("TRV GP IV LLC"). Abbie Celniker, Ph.D., Tepper, Alexis Borisy, Craig Muir and Cary Pfeffer, M.D. are the managing members of TRV IV LLC who collectively make voting and investment decisions with respect to shares held by TRV IV LP. Tepper disclaims beneficial ownership of the shares except to the extent of his pecuniary interest therein, if any, and this report shall not be deemed an admission that he is the beneficial owner of such shares.

F1 · ownership.direct: The shares are directly held by Third Rock Ventures III, L.P. ("TRV III"). The general partner of TRV III is Third Rock Ventures GP III, L.P. ("TRV GP III LP"). The general partner of TRV GP III LP is TRV GP III, LLC ("TRV GP III LLC"). The individual managers of TRV GP III LLC are Mark Levin ("Levin"), Kevin Starr ("Starr") and Dr. Robert Tepper ("Tepper"). Each of TRV GP III LP, TRV GP III LLC, Levin, Starr and Tepper disclaims beneficial ownership of the shares except to the extent of its or his pecuniary interest therein, if any, and this report shall not be deemed an admission that it or he is the beneficial owner of such shares.

SEC source: 0000899243-19-020026 · doc4.xml · derivative · entry 3

Third Rock Ventures III, L.P. · CIK 0001569705 · 10% owner

Third Rock Ventures GP III, L.P. · CIK 0001637300 · 10% owner

TRV GP III, LLC · CIK 0001637299 · 10% owner

STARR KEVIN P · CIK 0001192603 · 10% owner

TEPPER ROBERT I · CIK 0001192595 · 10% owner

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

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 5,595,238 shares

Expires not disclosed

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

F3 · derivative.exercise_price: On July 22, 2019, the Series A Preferred Stock converted into Common Stock on a seven-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series A Preferred Stock was convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial pubic offering. The shares had no expiration date.

F3 · derivative.exercise_date: On July 22, 2019, the Series A Preferred Stock converted into Common Stock on a seven-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series A Preferred Stock was convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial pubic offering. The shares had no expiration date.

F3 · derivative.expiration_date: On July 22, 2019, the Series A Preferred Stock converted into Common Stock on a seven-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series A Preferred Stock was convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial pubic offering. The shares had no expiration date.

F1 · ownership.direct: The shares are directly held by Third Rock Ventures III, L.P. ("TRV III"). The general partner of TRV III is Third Rock Ventures GP III, L.P. ("TRV GP III LP"). The general partner of TRV GP III LP is TRV GP III, LLC ("TRV GP III LLC"). The individual managers of TRV GP III LLC are Mark Levin ("Levin"), Kevin Starr ("Starr") and Dr. Robert Tepper ("Tepper"). Each of TRV GP III LP, TRV GP III LLC, Levin, Starr and Tepper disclaims beneficial ownership of the shares except to the extent of its or his pecuniary interest therein, if any, and this report shall not be deemed an admission that it or he is the beneficial owner of such shares.

SEC source: 0000899243-19-020026 · doc4.xml · nonDerivative · entry 2

Third Rock Ventures III, L.P. · CIK 0001569705 · 10% owner

Third Rock Ventures GP III, L.P. · CIK 0001637300 · 10% owner

TRV GP III, LLC · CIK 0001637299 · 10% owner

STARR KEVIN P · CIK 0001192603 · 10% owner

TEPPER ROBERT I · CIK 0001192595 · 10% owner

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

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 5,962,202

F2 · balance_after: As of the date of this filing, Third Rock Ventures IV, L.P. ("TRV IV") holds 2,261,904 shares of Common Stock issued upon conversion of 15,833,333 shares of Series A Preferred Stock. The general partner of TRV IV is Third Rock Ventures GP IV, L.P. ("TRV GP IV"). The general partner of TRV GP IV is TRV GP IV, LLC ("TRV GP IV LLC"). Abbie Celniker, Ph.D., Tepper, Alexis Borisy, Craig Muir and Cary Pfeffer, M.D. are the managing members of TRV IV LLC who collectively make voting and investment decisions with respect to shares held by TRV IV LP. Tepper disclaims beneficial ownership of the shares except to the extent of his pecuniary interest therein, if any, and this report shall not be deemed an admission that he is the beneficial owner of such shares.

F1 · ownership.direct: The shares are directly held by Third Rock Ventures III, L.P. ("TRV III"). The general partner of TRV III is Third Rock Ventures GP III, L.P. ("TRV GP III LP"). The general partner of TRV GP III LP is TRV GP III, LLC ("TRV GP III LLC"). The individual managers of TRV GP III LLC are Mark Levin ("Levin"), Kevin Starr ("Starr") and Dr. Robert Tepper ("Tepper"). Each of TRV GP III LP, TRV GP III LLC, Levin, Starr and Tepper disclaims beneficial ownership of the shares except to the extent of its or his pecuniary interest therein, if any, and this report shall not be deemed an admission that it or he is the beneficial owner of such shares.

SEC source: 0000899243-19-020026 · doc4.xml · nonDerivative · entry 1

Third Rock Ventures III, L.P. · CIK 0001569705 · 10% owner

Third Rock Ventures GP III, L.P. · CIK 0001637300 · 10% owner

TRV GP III, LLC · CIK 0001637299 · 10% owner

STARR KEVIN P · CIK 0001192603 · 10% owner

TEPPER ROBERT I · CIK 0001192595 · 10% owner

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

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 5,880,952

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

F3 · price: On July 22, 2019, the Series A Preferred Stock converted into Common Stock on a seven-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series A Preferred Stock was convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial pubic offering. The shares had no expiration date.

F2 · balance_after: As of the date of this filing, Third Rock Ventures IV, L.P. ("TRV IV") holds 2,261,904 shares of Common Stock issued upon conversion of 15,833,333 shares of Series A Preferred Stock. The general partner of TRV IV is Third Rock Ventures GP IV, L.P. ("TRV GP IV"). The general partner of TRV GP IV is TRV GP IV, LLC ("TRV GP IV LLC"). Abbie Celniker, Ph.D., Tepper, Alexis Borisy, Craig Muir and Cary Pfeffer, M.D. are the managing members of TRV IV LLC who collectively make voting and investment decisions with respect to shares held by TRV IV LP. Tepper disclaims beneficial ownership of the shares except to the extent of his pecuniary interest therein, if any, and this report shall not be deemed an admission that he is the beneficial owner of such shares.

F1 · ownership.direct: The shares are directly held by Third Rock Ventures III, L.P. ("TRV III"). The general partner of TRV III is Third Rock Ventures GP III, L.P. ("TRV GP III LP"). The general partner of TRV GP III LP is TRV GP III, LLC ("TRV GP III LLC"). The individual managers of TRV GP III LLC are Mark Levin ("Levin"), Kevin Starr ("Starr") and Dr. Robert Tepper ("Tepper"). Each of TRV GP III LP, TRV GP III LLC, Levin, Starr and Tepper disclaims beneficial ownership of the shares except to the extent of its or his pecuniary interest therein, if any, and this report shall not be deemed an admission that it or he is the beneficial owner of such shares.

SEC source: 0001104659-19-041306 · a4.xml · derivative · entry 5

Casdin Capital, LLC · CIK 0001534261 · 10% owner

Casdin Partners Master Fund, L.P. · CIK 0001534265 · 10% owner

Casdin Partners GP, LLC · CIK 0001534260 · 10% owner

Casdin Eli · CIK 0001534264 · 10% owner

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

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnote

Disclosed balance after: 0

Underlying: Common Stock · 464,285 shares

Expires not disclosed

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

F1 · derivative.exercise_price: On July 22, 2019, the Series B Preferred Stock converted into Common Stock on a seven-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series B Preferred Stock was convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F1 · derivative.exercise_date: On July 22, 2019, the Series B Preferred Stock converted into Common Stock on a seven-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series B Preferred Stock was convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F1 · derivative.expiration_date: On July 22, 2019, the Series B Preferred Stock converted into Common Stock on a seven-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series B Preferred Stock was convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F2 · ownership.nature: The securities are owned directly by Casdin Partners Master Fund, LP and may be deemed to be indirectly beneficially owned by (i) Casdin Capital, LLC, the investment adviser to Casdin Partners Master Fund, LP, (ii) Casdin Partners GP, LLC, the general partner of Casdin Partners Master Fund LP, and (ii) Eli Casdin, the managing member of Casdin Capital, LLC and Casdin Partners GP, LLC.

SEC source: 0001104659-19-041306 · a4.xml · nonDerivative · entry 4

Casdin Capital, LLC · CIK 0001534261 · 10% owner

Casdin Partners Master Fund, L.P. · CIK 0001534265 · 10% owner

Casdin Partners GP, LLC · CIK 0001534260 · 10% owner

Casdin Eli · CIK 0001534264 · 10% owner

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

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnote

Disclosed balance after: 604,285

F2 · ownership.nature: The securities are owned directly by Casdin Partners Master Fund, LP and may be deemed to be indirectly beneficially owned by (i) Casdin Capital, LLC, the investment adviser to Casdin Partners Master Fund, LP, (ii) Casdin Partners GP, LLC, the general partner of Casdin Partners Master Fund LP, and (ii) Eli Casdin, the managing member of Casdin Capital, LLC and Casdin Partners GP, LLC.

SEC source: 0001104659-19-041306 · a4.xml · nonDerivative · entry 3

Casdin Capital, LLC · CIK 0001534261 · 10% owner

Casdin Partners Master Fund, L.P. · CIK 0001534265 · 10% owner

Casdin Partners GP, LLC · CIK 0001534260 · 10% owner

Casdin Eli · CIK 0001534264 · 10% owner

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

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnote

Disclosed balance after: 599,285

F2 · ownership.nature: The securities are owned directly by Casdin Partners Master Fund, LP and may be deemed to be indirectly beneficially owned by (i) Casdin Capital, LLC, the investment adviser to Casdin Partners Master Fund, LP, (ii) Casdin Partners GP, LLC, the general partner of Casdin Partners Master Fund LP, and (ii) Eli Casdin, the managing member of Casdin Capital, LLC and Casdin Partners GP, LLC.

SEC source: 0001104659-19-041306 · a4.xml · nonDerivative · entry 2

Casdin Capital, LLC · CIK 0001534261 · 10% owner

Casdin Partners Master Fund, L.P. · CIK 0001534265 · 10% owner

Casdin Partners GP, LLC · CIK 0001534260 · 10% owner

Casdin Eli · CIK 0001534264 · 10% owner

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

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnote

Disclosed balance after: 589,285

F2 · ownership.nature: The securities are owned directly by Casdin Partners Master Fund, LP and may be deemed to be indirectly beneficially owned by (i) Casdin Capital, LLC, the investment adviser to Casdin Partners Master Fund, LP, (ii) Casdin Partners GP, LLC, the general partner of Casdin Partners Master Fund LP, and (ii) Eli Casdin, the managing member of Casdin Capital, LLC and Casdin Partners GP, LLC.

SEC source: 0001104659-19-041306 · a4.xml · nonDerivative · entry 1

Casdin Capital, LLC · CIK 0001534261 · 10% owner

Casdin Partners Master Fund, L.P. · CIK 0001534265 · 10% owner

Casdin Partners GP, LLC · CIK 0001534260 · 10% owner

Casdin Eli · CIK 0001534264 · 10% owner

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

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnote

Disclosed balance after: 464,285

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

F1 · price: On July 22, 2019, the Series B Preferred Stock converted into Common Stock on a seven-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series B Preferred Stock was convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F2 · ownership.nature: The securities are owned directly by Casdin Partners Master Fund, LP and may be deemed to be indirectly beneficially owned by (i) Casdin Capital, LLC, the investment adviser to Casdin Partners Master Fund, LP, (ii) Casdin Partners GP, LLC, the general partner of Casdin Partners Master Fund LP, and (ii) Eli Casdin, the managing member of Casdin Capital, LLC and Casdin Partners GP, LLC.

SEC source: 0001104659-19-041303 · a4.xml · derivative · entry 2

Section 32 Fund 2, LP · CIK 0001725306 · 10% owner

Section 32 GP 2, LLC · CIK 0001725307 · 10% owner

Maris William J · CIK 0001722210 · 10% owner

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

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 464,285 shares

Expires not disclosed

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

F1 · derivative.exercise_price: On July 22, 2019, the Series B Preferred Stock converted into Common Stock on a seven-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series B Preferred Stock was convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F1 · derivative.exercise_date: On July 22, 2019, the Series B Preferred Stock converted into Common Stock on a seven-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series B Preferred Stock was convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F1 · derivative.expiration_date: On July 22, 2019, the Series B Preferred Stock converted into Common Stock on a seven-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series B Preferred Stock was convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F2 · ownership.direct: The reported securities are held of record by Section 32 Fund 2, LP ("Fund 2"). Section 32 GP 2, LLC (the "GP"), the general partner of Fund 2, and William J. Maris, the managing member of the GP, may be deemed to share voting and dispositive power over the shares held by Fund 2. Such person and entity disclaim beneficial ownership of shares held by Fund 2 except to the extent of any pecuniary interest therein.

SEC source: 0001104659-19-041303 · a4.xml · nonDerivative · entry 1

Section 32 Fund 2, LP · CIK 0001725306 · 10% owner

Section 32 GP 2, LLC · CIK 0001725307 · 10% owner

Maris William J · CIK 0001722210 · 10% owner

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

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 464,285

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

F1 · price: On July 22, 2019, the Series B Preferred Stock converted into Common Stock on a seven-for-one basis upon the closing of the Issuer's initial public offering without payment of consideration. The Series B Preferred Stock was convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares had no expiration date.

F2 · ownership.direct: The reported securities are held of record by Section 32 Fund 2, LP ("Fund 2"). Section 32 GP 2, LLC (the "GP"), the general partner of Fund 2, and William J. Maris, the managing member of the GP, may be deemed to share voting and dispositive power over the shares held by Fund 2. Such person and entity disclaim beneficial ownership of shares held by Fund 2 except to the extent of any pecuniary interest therein.

SEC source: 0000899243-19-020073 · doc4.xml · derivative · entry 3

Sanofi · CIK 0001121404 · 10% owner

10b5-1 filing: Not disclosed

Ownership: Indirect · Through its wholly-owned subsidiary, Aventis Inc.

Disclosed balance after: 0

Underlying: Common Stock · 464,285 shares

Expires not disclosed

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

F1 · derivative.exercise_price: On July 22, 2019, the Series B Preferred Stock converted into the Issuer's Common Stock on a seven-for-one basis automatically upon the closing of the Issuer's initial public offering without payment or further consideration. The shares have no expiration date. As a result of the Issuer's initial public offering, the reporting person is no longer a 10% owner of FULC and is therefore no longer subject to Section 16 in connection with its transactions in the equity securities of FULC.

F1 · price: On July 22, 2019, the Series B Preferred Stock converted into the Issuer's Common Stock on a seven-for-one basis automatically upon the closing of the Issuer's initial public offering without payment or further consideration. The shares have no expiration date. As a result of the Issuer's initial public offering, the reporting person is no longer a 10% owner of FULC and is therefore no longer subject to Section 16 in connection with its transactions in the equity securities of FULC.

F1 · derivative.exercise_date: On July 22, 2019, the Series B Preferred Stock converted into the Issuer's Common Stock on a seven-for-one basis automatically upon the closing of the Issuer's initial public offering without payment or further consideration. The shares have no expiration date. As a result of the Issuer's initial public offering, the reporting person is no longer a 10% owner of FULC and is therefore no longer subject to Section 16 in connection with its transactions in the equity securities of FULC.

F1 · derivative.expiration_date: On July 22, 2019, the Series B Preferred Stock converted into the Issuer's Common Stock on a seven-for-one basis automatically upon the closing of the Issuer's initial public offering without payment or further consideration. The shares have no expiration date. As a result of the Issuer's initial public offering, the reporting person is no longer a 10% owner of FULC and is therefore no longer subject to Section 16 in connection with its transactions in the equity securities of FULC.

SEC source: 0000899243-19-020073 · doc4.xml · nonDerivative · entry 2

Sanofi · CIK 0001121404 · 10% owner

10b5-1 filing: Not disclosed

Ownership: Indirect · Through its wholly-owned subsidiary, Aventis Inc.

Disclosed balance after: 558,035

F2 · kind: The reporting person acquired additional shares in the Issuer's initial public offering.

F2 · price: The reporting person acquired additional shares in the Issuer's initial public offering.

SEC source: 0000899243-19-020073 · doc4.xml · nonDerivative · entry 1

Sanofi · CIK 0001121404 · 10% owner

10b5-1 filing: Not disclosed

Ownership: Indirect · Through its wholly-owned subsidiary, Aventis Inc.

Disclosed balance after: 464,285

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

F1 · price: On July 22, 2019, the Series B Preferred Stock converted into the Issuer's Common Stock on a seven-for-one basis automatically upon the closing of the Issuer's initial public offering without payment or further consideration. The shares have no expiration date. As a result of the Issuer's initial public offering, the reporting person is no longer a 10% owner of FULC and is therefore no longer subject to Section 16 in connection with its transactions in the equity securities of FULC.

SEC source: 0001140361-19-013355 · form4.xml · derivative · entry 2

GLAXOSMITHKLINE PLC · CIK 0001131399 · 10% owner

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnote

Disclosed balance after: 0

Underlying: Common Stock · 1,785,714 shares

Expires not disclosed

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

F1 · derivative.exercise_price: On July 22, 2019 upon the closing of the Issuer's initial public offering (the "IPO"), the Series B Preferred Stock converted into Common Stock on a seven-for-one basis without payment of consideration. The Series B Preferred Stock was convertible at any time at the holder's election and automatically upon the closing of the IPO. The shares had no expiration date.

F1 · derivative.exercise_date: On July 22, 2019 upon the closing of the Issuer's initial public offering (the "IPO"), the Series B Preferred Stock converted into Common Stock on a seven-for-one basis without payment of consideration. The Series B Preferred Stock was convertible at any time at the holder's election and automatically upon the closing of the IPO. The shares had no expiration date.

F1 · derivative.expiration_date: On July 22, 2019 upon the closing of the Issuer's initial public offering (the "IPO"), the Series B Preferred Stock converted into Common Stock on a seven-for-one basis without payment of consideration. The Series B Preferred Stock was convertible at any time at the holder's election and automatically upon the closing of the IPO. The shares had no expiration date.

F2 · ownership.nature: The shares reported herein are held of record by Glaxo Group Limited, an indirect, wholly-owned subsidiary of GlaxoSmithKline plc (the "Reporting Person").

SEC source: 0001140361-19-013355 · form4.xml · nonDerivative · entry 1

GLAXOSMITHKLINE PLC · CIK 0001131399 · 10% owner

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 1,785,714

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

F1 · price: On July 22, 2019 upon the closing of the Issuer's initial public offering (the "IPO"), the Series B Preferred Stock converted into Common Stock on a seven-for-one basis without payment of consideration. The Series B Preferred Stock was convertible at any time at the holder's election and automatically upon the closing of the IPO. The shares had no expiration date.

F2 · ownership.nature: The shares reported herein are held of record by Glaxo Group Limited, an indirect, wholly-owned subsidiary of GlaxoSmithKline plc (the "Reporting Person").

SEC source: 0001104659-19-040965 · a4.xml · derivative · entry 1

Thomson Peter G. · CIK 0001779120 · See Remarks

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 7,078

Underlying: Common Stock · 7,078 shares

Expires 2029-07-17

F1 · derivative.exercise_date: The option was granted on July 18, 2019. The shares underlying the option are scheduled to vest in equal quarterly installments from July 1, 2019 through June 30, 2023.

SEC source: 0001104659-19-040972 · a4.xml · derivative · entry 1

Collins James J. · CIK 0001779269 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 5,714

Underlying: Common Stock · 5,714 shares

Expires 2029-07-17

F1 · derivative.exercise_date: The option was granted on July 18, 2019. The shares underlying the option are scheduled to vest on July 18, 2020 or, if earlier, immediately prior to the first annual meeting of stockholders occurring after the grant date.

SEC source: 0001104659-19-040970 · a4.xml · derivative · entry 1

Ezekowitz Alan · CIK 0001780209 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 5,714

Underlying: Common Stock · 5,714 shares

Expires 2029-07-17

F1 · derivative.exercise_date: The option was granted on July 18, 2019. The shares underlying the option are scheduled to vest on July 18, 2020 or, if earlier, immediately prior to the first annual meeting of stockholders occurring after the grant date.

SEC source: 0001104659-19-040968 · a4.xml · derivative · entry 1

Gould Robert J · CIK 0001577034 · Director · See Remarks · 10% owner

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 107,142

Underlying: Common Stock · 107,142 shares

Expires 2029-07-17

F1 · derivative.exercise_date: The option was granted on July 18, 2019. The shares underlying the option are scheduled to vest in equal quarterly installments from July 1, 2019 through June 30, 2023.

SEC source: 0001104659-19-040971 · a4.xml · derivative · entry 1

GERAGHTY JAMES A · CIK 0001239746 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 9,285

Underlying: Common Stock · 9,285 shares

Expires 2029-07-17

F1 · derivative.exercise_date: The option was granted on July 18, 2019. The shares underlying the option are scheduled to vest on July 18, 2020 or, if earlier, immediately prior to the first annual meeting of stockholders occurring after the grant date.

SEC source: 0001104659-19-040967 · a4.xml · derivative · entry 1

Cadavid Diego · CIK 0001778713 · See Remarks

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 12,784

Underlying: Common Stock · 12,784 shares

Expires 2029-07-17

F1 · derivative.exercise_date: The option was granted on July 18, 2019. The shares underlying the option are scheduled to vest in equal quarterly installments from July 1, 2019 through June 30, 2023.

SEC source: 0001104659-19-040969 · a4.xml · derivative · entry 1

Haviland Kate · CIK 0001663022 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 9,285

Underlying: Common Stock · 9,285 shares

Expires 2029-07-17

F1 · derivative.exercise_date: The option was granted on July 18, 2019. The shares underlying the option are scheduled to vest on July 18, 2020 or, if earlier, immediately prior to the first annual meeting of stockholders occurring after the grant date.

SEC source: 0001104659-19-040966 · a4.xml · derivative · entry 1

Stuart Bryan · CIK 0001619846 · Chief Operating Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 28,571

Underlying: Common Stock · 28,571 shares

Expires 2029-07-17

F1 · derivative.exercise_date: The option was granted on July 18, 2019. The shares underlying the option are scheduled to vest in equal quarterly installments from July 1, 2019 through June 30, 2023.

SEC source: 0001104659-19-040973 · a4.xml · derivative · entry 1

Wallace Owen B. · CIK 0001778843 · Chief Scientific Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 44,493

Underlying: Common Stock · 44,493 shares

Expires 2029-07-17

F1 · derivative.exercise_date: The option was granted on July 18, 2019. The shares underlying the option are scheduled to vest in equal quarterly installments from July 1, 2019 through June 30, 2023.