MRNA

SEC source: 0001127602-19-028728 · form4.xml · derivative · entry 3

HUTT PETER BARTON · CIK 0001171527 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 702,752

Underlying: Common Stock · 100,000 shares

Expires 2022-03-27

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

F2 · derivative.exercise_date: This option is fully vested and exercisable.

SEC source: 0001127602-19-028728 · form4.xml · nonDerivative · entry 2

HUTT PETER BARTON · CIK 0001171527 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 3,924

F1 · price: The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $17.31 to $17.94. Full information regarding the number of shares sold at each separate price can be furnished to the SEC staff upon request.

SEC source: 0001127602-19-028728 · form4.xml · nonDerivative · entry 1

HUTT PETER BARTON · CIK 0001171527 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 103,924

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.

SEC source: 0001127602-19-023027 · form4.xml · derivative · entry 1

SAGAN PAUL · CIK 0001035440 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 54,660

Underlying: Common Stock · 54,660 shares

Expires 2029-06-27

F1 · derivative.exercise_date: This option will become fully vested and exercisable on the earlier of June 27, 2020, or the next Annual Meeting of Stockholders, subject to the recipient's continued service.

SEC source: 0001127602-19-023015 · form4.xml · derivative · entry 1

HUTT PETER BARTON · CIK 0001171527 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 54,660

Underlying: Common Stock · 54,660 shares

Expires 2029-06-27

F1 · derivative.exercise_date: This option will become fully vested and exercisable on the earlier of June 27, 2020, or the next Annual Meeting of Stockholders, subject to the recipient's continued service.

SEC source: 0001127602-19-023012 · form4.xml · derivative · entry 1

Berenson Stephen · CIK 0001760671 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 54,660

Underlying: Common Stock · 54,660 shares

Expires 2029-06-27

F1 · derivative.exercise_date: This option will become fully vested and exercisable on the earlier of June 27, 2020, or the next Annual Meeting of Stockholders, subject to the recipient's continued service.

SEC source: 0001127602-19-023031 · form4.xml · derivative · entry 1

Ruiz Israel · CIK 0001670805 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 54,660

Underlying: Common Stock · 54,660 shares

Expires 2029-06-27

F1 · derivative.exercise_date: This option will become fully vested and exercisable on the earlier of June 27, 2020, or the next Annual Meeting of Stockholders, subject to the recipient's continued service.

SEC source: 0001127602-19-023029 · form4.xml · derivative · entry 1

Slaoui Moncef · CIK 0001712369 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 54,660

Underlying: Common Stock · 54,660 shares

Expires 2029-06-27

F1 · derivative.exercise_date: This option will become fully vested and exercisable on the earlier of June 27, 2020, or the next Annual Meeting of Stockholders, subject to the recipient's continued service.

SEC source: 0001127602-19-023019 · form4.xml · derivative · entry 1

NABEL ELIZABETH G · CIK 0001619929 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 54,660

Underlying: Common Stock · 54,660 shares

Expires 2029-06-27

F1 · derivative.exercise_date: This option will become fully vested and exercisable on the earlier of June 27, 2020, or the next Annual Meeting of Stockholders, subject to the recipient's continued service.

SEC source: 0001127602-19-023017 · form4.xml · derivative · entry 1

LANGER ROBERT · CIK 0001239757 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 54,660

Underlying: Common Stock · 54,660 shares

Expires 2029-06-27

F1 · derivative.exercise_date: This option will become fully vested and exercisable on the earlier of June 27, 2020, or the next Annual Meeting of Stockholders, subject to the recipient's continued service.

SEC source: 0001127602-19-023011 · form4.xml · derivative · entry 1

AFEYAN NOUBAR · CIK 0001222012 · Director · 10% owner

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 54,660

Underlying: Common Stock · 54,660 shares

Expires 2029-06-27

F1 · derivative.exercise_date: This option will become fully vested and exercisable on the earlier of June 27, 2020, or the next Annual Meeting of Stockholders, subject to the recipient's continued service.

SEC source: 0001127602-19-010855 · form4.xml · derivative · entry 1

Zaks Tal Zvi · CIK 0001690927 · Chief Medical Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 339,195

Underlying: Common Stock · 339,195 shares

Expires 2029-03-08

F1 · derivative.exercise_date: 25% of this option will vest and become exercisable on March 8, 2020 with the remainder vesting in twelve (12) equal quarterly installments thereafter.

SEC source: 0001127602-19-010856 · form4.xml · derivative · entry 1

Hoge Stephen · CIK 0001760669 · President

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 339,195

Underlying: Common Stock · 339,195 shares

Expires 2029-03-08

F1 · derivative.exercise_date: 25% of this option will vest and become exercisable on March 8, 2020 with the remainder vesting in twelve (12) equal quarterly installments thereafter.

SEC source: 0001127602-19-010857 · form4.xml · derivative · entry 1

Kim Lorence H. · CIK 0001643746 · Chief Financial Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 211,997

Underlying: Common Stock · 211,997 shares

Expires 2029-03-08

F1 · derivative.exercise_date: 25% of this option will vest and become exercisable on March 8, 2020 with the remainder vesting in twelve (12) equal quarterly installments thereafter.

SEC source: 0001127602-19-010860 · form4.xml · derivative · entry 1

Bancel Stephane · CIK 0001443340 · Director · Chief Executive Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 593,592

Underlying: Common Stock · 593,592 shares

Expires 2029-03-08

F1 · derivative.exercise_date: 25% of this option will vest and become exercisable on March 8, 2020 with the remainder vesting in twelve (12) equal quarterly installments thereafter.

SEC source: 0001127602-19-010852 · form4.xml · derivative · entry 1

Andres Juan · CIK 0001760670 · See remarks

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 254,396

Underlying: Common Stock · 254,396 shares

Expires 2029-03-08

F1 · derivative.exercise_date: 25% of this option will vest and become exercisable on March 8, 2020 with the remainder vesting in twelve (12) equal quarterly installments thereafter.

SEC source: 0001127602-19-010846 · form4.xml · derivative · entry 1

HENDERSON LORI M. · CIK 0001221127 · General Counsel and Secretary

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 186,092

Underlying: Common Stock · 186,092 shares

Expires 2029-03-08

F1 · derivative.exercise_date: 25% of this option will vest and become exercisable on March 8, 2020 with the remainder vesting in twelve (12) equal quarterly installments thereafter.

SEC source: 0001127602-19-010841 · form4.xml · derivative · entry 2

LEE JENNIFER LING · CIK 0001675118 · Chief Accounting Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 25,097

Underlying: Common Stock · 25,097 shares

Expires 2029-03-08

F2 · derivative.exercise_date: 25% of this option will vest and become exercisable on March 8, 2020 with the remainder vesting in twelve (12) equal quarterly installments thereafter.

SEC source: 0001127602-19-010841 · form4.xml · nonDerivative · entry 1

LEE JENNIFER LING · CIK 0001675118 · Chief Accounting Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 4,780

F1 · shares: 25% of the shares subject to this restricted stock unit award will vest on March 8, 2020 with the remainder vesting in twelve (12) equal quarterly installments thereafter.

SEC source: 0000899243-18-030866 · doc4.xml · derivative · entry 4

SAGAN PAUL · CIK 0001035440 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · By: The Paul Sagan Revocable Trust

Disclosed balance after: 0

Underlying: Common Stock · 367,776 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: The Series B Preferred Stock (the "Preferred Stock") converted into Common Stock based on an applicable conversion ratio of 0.45457 upon the closing of the Issuer's initial public offering on December 11, 2018. The Preferred Stock had no expiration date.

F1 · price: The Series B Preferred Stock (the "Preferred Stock") converted into Common Stock based on an applicable conversion ratio of 0.45457 upon the closing of the Issuer's initial public offering on December 11, 2018. The Preferred Stock had no expiration date.

F1 · derivative.exercise_date: The Series B Preferred Stock (the "Preferred Stock") converted into Common Stock based on an applicable conversion ratio of 0.45457 upon the closing of the Issuer's initial public offering on December 11, 2018. The Preferred Stock had no expiration date.

F1 · derivative.expiration_date: The Series B Preferred Stock (the "Preferred Stock") converted into Common Stock based on an applicable conversion ratio of 0.45457 upon the closing of the Issuer's initial public offering on December 11, 2018. The Preferred Stock had no expiration date.

F2 · derivative.underlying_shares: Erwin Park LLC is an estate planning vehicle for the Reporting Person's family. The Chatham Trust is an irrevocable family trust for which the Reporting Person serves as a trustee. The Paul Sagan Revocable Trust is a revocable trust for which the Reporting Person serves as a trustee. The Reporting Person disclaims beneficial ownership of these securities except to the extent of his pecuniary interest therein, and the inclusion of these shares in this report shall not be deemed an admission of beneficial ownership of all of the reported shares for purposes of Section 16 or for any other purpose.

SEC source: 0000899243-18-030866 · doc4.xml · nonDerivative · entry 1

SAGAN PAUL · CIK 0001035440 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · By: The Paul Sagan Revocable Trust

Disclosed balance after: 367,776

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: The Series B Preferred Stock (the "Preferred Stock") converted into Common Stock based on an applicable conversion ratio of 0.45457 upon the closing of the Issuer's initial public offering on December 11, 2018. The Preferred Stock had no expiration date.

F2 · balance_after: Erwin Park LLC is an estate planning vehicle for the Reporting Person's family. The Chatham Trust is an irrevocable family trust for which the Reporting Person serves as a trustee. The Paul Sagan Revocable Trust is a revocable trust for which the Reporting Person serves as a trustee. The Reporting Person disclaims beneficial ownership of these securities except to the extent of his pecuniary interest therein, and the inclusion of these shares in this report shall not be deemed an admission of beneficial ownership of all of the reported shares for purposes of Section 16 or for any other purpose.

SEC source: 0000899243-18-030879 · doc4.xml · derivative · entry 3

Hoge Stephen · CIK 0001760669 · President

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 458 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: The Series E Preferred Stock (the "Preferred Stock") converted into Common Stock based on an applicable conversion ratio of 0.45859 upon the closing of the Issuer's initial public offering on December 11, 2018. The Preferred Stock had no expiration date.

F1 · price: The Series E Preferred Stock (the "Preferred Stock") converted into Common Stock based on an applicable conversion ratio of 0.45859 upon the closing of the Issuer's initial public offering on December 11, 2018. The Preferred Stock had no expiration date.

F1 · derivative.exercise_date: The Series E Preferred Stock (the "Preferred Stock") converted into Common Stock based on an applicable conversion ratio of 0.45859 upon the closing of the Issuer's initial public offering on December 11, 2018. The Preferred Stock had no expiration date.

F1 · derivative.expiration_date: The Series E Preferred Stock (the "Preferred Stock") converted into Common Stock based on an applicable conversion ratio of 0.45859 upon the closing of the Issuer's initial public offering on December 11, 2018. The Preferred Stock had no expiration date.

SEC source: 0000899243-18-030879 · doc4.xml · nonDerivative · entry 1

Hoge Stephen · CIK 0001760669 · President

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 2,096,530

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: The Series E Preferred Stock (the "Preferred Stock") converted into Common Stock based on an applicable conversion ratio of 0.45859 upon the closing of the Issuer's initial public offering on December 11, 2018. The Preferred Stock had no expiration date.

SEC source: 0000899243-18-030863 · doc4.xml · derivative · entry 2

Berenson Stephen · CIK 0001760671 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 22,798 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: The Series G Preferred Stock (the "Preferred Stock") converted into Common Stock based on an applicable conversion ratio of 0.45872 upon the closing of the Issuer's initial public offering on December 11, 2018. The Preferred Stock had no expiration date.

F1 · price: The Series G Preferred Stock (the "Preferred Stock") converted into Common Stock based on an applicable conversion ratio of 0.45872 upon the closing of the Issuer's initial public offering on December 11, 2018. The Preferred Stock had no expiration date.

F1 · derivative.exercise_date: The Series G Preferred Stock (the "Preferred Stock") converted into Common Stock based on an applicable conversion ratio of 0.45872 upon the closing of the Issuer's initial public offering on December 11, 2018. The Preferred Stock had no expiration date.

F1 · derivative.expiration_date: The Series G Preferred Stock (the "Preferred Stock") converted into Common Stock based on an applicable conversion ratio of 0.45872 upon the closing of the Issuer's initial public offering on December 11, 2018. The Preferred Stock had no expiration date.

SEC source: 0000899243-18-030863 · doc4.xml · nonDerivative · entry 1

Berenson Stephen · CIK 0001760671 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 22,798

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: The Series G Preferred Stock (the "Preferred Stock") converted into Common Stock based on an applicable conversion ratio of 0.45872 upon the closing of the Issuer's initial public offering on December 11, 2018. The Preferred Stock had no expiration date.

SEC source: 0000899243-18-030873 · doc4.xml · derivative · entry 2

NABEL ELIZABETH G · CIK 0001619929 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 13,679 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: The Series G Preferred Stock (the "Preferred Stock") converted into Common Stock based on an applicable conversion ratio of 0.45872 upon the closing of the Issuer's initial public offering on December 11, 2018. The Preferred Stock had no expiration date.

F1 · price: The Series G Preferred Stock (the "Preferred Stock") converted into Common Stock based on an applicable conversion ratio of 0.45872 upon the closing of the Issuer's initial public offering on December 11, 2018. The Preferred Stock had no expiration date.

F1 · derivative.exercise_date: The Series G Preferred Stock (the "Preferred Stock") converted into Common Stock based on an applicable conversion ratio of 0.45872 upon the closing of the Issuer's initial public offering on December 11, 2018. The Preferred Stock had no expiration date.

F1 · derivative.expiration_date: The Series G Preferred Stock (the "Preferred Stock") converted into Common Stock based on an applicable conversion ratio of 0.45872 upon the closing of the Issuer's initial public offering on December 11, 2018. The Preferred Stock had no expiration date.

SEC source: 0000899243-18-030873 · doc4.xml · nonDerivative · entry 1

NABEL ELIZABETH G · CIK 0001619929 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 44,344

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: The Series G Preferred Stock (the "Preferred Stock") converted into Common Stock based on an applicable conversion ratio of 0.45872 upon the closing of the Issuer's initial public offering on December 11, 2018. The Preferred Stock had no expiration date.

SEC source: 0000899243-18-030869 · doc4.xml · derivative · entry 5

LANGER ROBERT · CIK 0001239757 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 4,559 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: The Series G Preferred Stock (the "Preferred Stock") converted into Common Stock based on an applicable conversion ratio of 0.45872 upon the closing of the Issuer's initial public offering on December 11, 2018. The Preferred Stock had no expiration date.

F1 · price: The Series G Preferred Stock (the "Preferred Stock") converted into Common Stock based on an applicable conversion ratio of 0.45872 upon the closing of the Issuer's initial public offering on December 11, 2018. The Preferred Stock had no expiration date.

F1 · derivative.exercise_date: The Series G Preferred Stock (the "Preferred Stock") converted into Common Stock based on an applicable conversion ratio of 0.45872 upon the closing of the Issuer's initial public offering on December 11, 2018. The Preferred Stock had no expiration date.

F1 · derivative.expiration_date: The Series G Preferred Stock (the "Preferred Stock") converted into Common Stock based on an applicable conversion ratio of 0.45872 upon the closing of the Issuer's initial public offering on December 11, 2018. The Preferred Stock had no expiration date.

SEC source: 0000899243-18-030869 · doc4.xml · nonDerivative · entry 1

LANGER ROBERT · CIK 0001239757 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 11,466,961

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: The Series G Preferred Stock (the "Preferred Stock") converted into Common Stock based on an applicable conversion ratio of 0.45872 upon the closing of the Issuer's initial public offering on December 11, 2018. The Preferred Stock had no expiration date.

SEC source: 0000899243-18-030864 · doc4.xml · derivative · entry 2

Ruiz Israel · CIK 0001670805 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 4,559 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: The Series G Preferred Stock (the "Preferred Stock") converted into Common Stock based on an applicable conversion ratio of 0.45872 upon the closing of the Issuer's initial public offering on December 11, 2018. The Preferred Stock had no expiration date.

F1 · price: The Series G Preferred Stock (the "Preferred Stock") converted into Common Stock based on an applicable conversion ratio of 0.45872 upon the closing of the Issuer's initial public offering on December 11, 2018. The Preferred Stock had no expiration date.

F1 · derivative.exercise_date: The Series G Preferred Stock (the "Preferred Stock") converted into Common Stock based on an applicable conversion ratio of 0.45872 upon the closing of the Issuer's initial public offering on December 11, 2018. The Preferred Stock had no expiration date.

F1 · derivative.expiration_date: The Series G Preferred Stock (the "Preferred Stock") converted into Common Stock based on an applicable conversion ratio of 0.45872 upon the closing of the Issuer's initial public offering on December 11, 2018. The Preferred Stock had no expiration date.

SEC source: 0000899243-18-030864 · doc4.xml · nonDerivative · entry 1

Ruiz Israel · CIK 0001670805 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 4,559

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: The Series G Preferred Stock (the "Preferred Stock") converted into Common Stock based on an applicable conversion ratio of 0.45872 upon the closing of the Issuer's initial public offering on December 11, 2018. The Preferred Stock had no expiration date.

SEC source: 0000899243-18-030859 · doc4.xml · derivative · entry 18

AFEYAN NOUBAR · CIK 0001222012 · Director · 10% owner

Flagship Ventures Fund IV General Partner LLC · CIK 0001508051 · 10% owner

Flagship Pioneering Inc. · CIK 0001400240 · 10% owner

Flagship VentureLabs IV, LLC · CIK 0001642578 · 10% owner

Flagship Ventures Fund IV, L.P. · CIK 0001503559 · 10% owner

Flagship Ventures Fund IV-Rx, L.P. · CIK 0001590973 · 10% owner

KANIA EDWIN M JR · CIK 0001255927 · 10% owner

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

10b5-1 filing: Not disclosed

Ownership: Indirect · By: Flagship Ventures Fund IV-Rx, LP

Disclosed balance after: 0

Underlying: Common Stock · 21,496 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.

F8 · derivative.exercise_price: The Series D Preferred Stock converted into Common Stock based on an applicable conversion ratio of 0.45854 upon the closing of the Issuer's initial public offering on December 11, 2018. The Series D Preferred Stock had no expiration date.

F8 · price: The Series D Preferred Stock converted into Common Stock based on an applicable conversion ratio of 0.45854 upon the closing of the Issuer's initial public offering on December 11, 2018. The Series D Preferred Stock had no expiration date.

F8 · derivative.exercise_date: The Series D Preferred Stock converted into Common Stock based on an applicable conversion ratio of 0.45854 upon the closing of the Issuer's initial public offering on December 11, 2018. The Series D Preferred Stock had no expiration date.

F8 · derivative.expiration_date: The Series D Preferred Stock converted into Common Stock based on an applicable conversion ratio of 0.45854 upon the closing of the Issuer's initial public offering on December 11, 2018. The Series D Preferred Stock had no expiration date.

F2 · ownership.nature: Shares held by Flagship Ventures Fund IV-Rx, L.P. ("Flagship Fund IV-Rx"). Flagship Fund IV GP is the general partner of Flagship Fund IV-Rx. While Mr. Kania is retired from Pioneering he continues to serve as a manager of the Flagship Fund IV GP. Each of the reporting persons except for Flagship Fund IV-Rx disclaims beneficial ownership of such shares except to the extent of his or its pecuniary interest therein.

SEC source: 0000899243-18-030859 · doc4.xml · derivative · entry 17

AFEYAN NOUBAR · CIK 0001222012 · Director · 10% owner

Flagship Ventures Fund IV General Partner LLC · CIK 0001508051 · 10% owner

Flagship Pioneering Inc. · CIK 0001400240 · 10% owner

Flagship VentureLabs IV, LLC · CIK 0001642578 · 10% owner

Flagship Ventures Fund IV, L.P. · CIK 0001503559 · 10% owner

Flagship Ventures Fund IV-Rx, L.P. · CIK 0001590973 · 10% owner

KANIA EDWIN M JR · CIK 0001255927 · 10% owner

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

10b5-1 filing: Not disclosed

Ownership: Indirect · By: Flagship Ventures Fund IV, LP

Disclosed balance after: 0

Underlying: Common Stock · 85,989 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.

F8 · derivative.exercise_price: The Series D Preferred Stock converted into Common Stock based on an applicable conversion ratio of 0.45854 upon the closing of the Issuer's initial public offering on December 11, 2018. The Series D Preferred Stock had no expiration date.

F8 · price: The Series D Preferred Stock converted into Common Stock based on an applicable conversion ratio of 0.45854 upon the closing of the Issuer's initial public offering on December 11, 2018. The Series D Preferred Stock had no expiration date.

F8 · derivative.exercise_date: The Series D Preferred Stock converted into Common Stock based on an applicable conversion ratio of 0.45854 upon the closing of the Issuer's initial public offering on December 11, 2018. The Series D Preferred Stock had no expiration date.

F8 · derivative.expiration_date: The Series D Preferred Stock converted into Common Stock based on an applicable conversion ratio of 0.45854 upon the closing of the Issuer's initial public offering on December 11, 2018. The Series D Preferred Stock had no expiration date.

F1 · ownership.nature: Shares held by Flagship Ventures Fund IV, L.P. ("Flagship Fund IV"). Flagship Ventures Fund IV General Partner LLC ("Flagship Fund IV GP") is the general partner of Flagship Fund IV. Noubar B. Afeyan, Ph.D. and Edwin M. Kania, Jr. are the managers of Flagship Fund IV GP. While Mr. Kania is retired from Flagship Pioneering, Inc. ("Pioneering"), he continues to serve as a manager of Flagship Fund IV GP. Each of the reporting persons except for Flagship Fund IV disclaims beneficial ownership of such shares except to the extent of his or its pecuniary interest therein.

SEC source: 0000899243-18-030859 · doc4.xml · derivative · entry 16

AFEYAN NOUBAR · CIK 0001222012 · Director · 10% owner

Flagship Ventures Fund IV General Partner LLC · CIK 0001508051 · 10% owner

Flagship Pioneering Inc. · CIK 0001400240 · 10% owner

Flagship VentureLabs IV, LLC · CIK 0001642578 · 10% owner

Flagship Ventures Fund IV, L.P. · CIK 0001503559 · 10% owner

Flagship Ventures Fund IV-Rx, L.P. · CIK 0001590973 · 10% owner

KANIA EDWIN M JR · CIK 0001255927 · 10% owner

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

10b5-1 filing: Not disclosed

Ownership: Indirect · By: Flagship Ventures Fund IV-Rx, LP

Disclosed balance after: 0

Underlying: Common Stock · 1,428,432 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.

F7 · derivative.exercise_price: The Series C Preferred Stock converted into Common Stock based on an applicable conversion ratio of 0.45853 upon the closing of the Issuer's initial public offering on December 11, 2018. The Series C Preferred Stock had no expiration date.

F7 · price: The Series C Preferred Stock converted into Common Stock based on an applicable conversion ratio of 0.45853 upon the closing of the Issuer's initial public offering on December 11, 2018. The Series C Preferred Stock had no expiration date.

F7 · derivative.exercise_date: The Series C Preferred Stock converted into Common Stock based on an applicable conversion ratio of 0.45853 upon the closing of the Issuer's initial public offering on December 11, 2018. The Series C Preferred Stock had no expiration date.

F7 · derivative.expiration_date: The Series C Preferred Stock converted into Common Stock based on an applicable conversion ratio of 0.45853 upon the closing of the Issuer's initial public offering on December 11, 2018. The Series C Preferred Stock had no expiration date.

F2 · ownership.nature: Shares held by Flagship Ventures Fund IV-Rx, L.P. ("Flagship Fund IV-Rx"). Flagship Fund IV GP is the general partner of Flagship Fund IV-Rx. While Mr. Kania is retired from Pioneering he continues to serve as a manager of the Flagship Fund IV GP. Each of the reporting persons except for Flagship Fund IV-Rx disclaims beneficial ownership of such shares except to the extent of his or its pecuniary interest therein.

SEC source: 0000899243-18-030859 · doc4.xml · derivative · entry 15

AFEYAN NOUBAR · CIK 0001222012 · Director · 10% owner

Flagship Ventures Fund IV General Partner LLC · CIK 0001508051 · 10% owner

Flagship Pioneering Inc. · CIK 0001400240 · 10% owner

Flagship VentureLabs IV, LLC · CIK 0001642578 · 10% owner

Flagship Ventures Fund IV, L.P. · CIK 0001503559 · 10% owner

Flagship Ventures Fund IV-Rx, L.P. · CIK 0001590973 · 10% owner

KANIA EDWIN M JR · CIK 0001255927 · 10% owner

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

10b5-1 filing: Not disclosed

Ownership: Indirect · By: Flagship Ventures Fund IV, LP

Disclosed balance after: 0

Underlying: Common Stock · 5,713,739 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.

F7 · derivative.exercise_price: The Series C Preferred Stock converted into Common Stock based on an applicable conversion ratio of 0.45853 upon the closing of the Issuer's initial public offering on December 11, 2018. The Series C Preferred Stock had no expiration date.

F7 · price: The Series C Preferred Stock converted into Common Stock based on an applicable conversion ratio of 0.45853 upon the closing of the Issuer's initial public offering on December 11, 2018. The Series C Preferred Stock had no expiration date.

F7 · derivative.exercise_date: The Series C Preferred Stock converted into Common Stock based on an applicable conversion ratio of 0.45853 upon the closing of the Issuer's initial public offering on December 11, 2018. The Series C Preferred Stock had no expiration date.

F7 · derivative.expiration_date: The Series C Preferred Stock converted into Common Stock based on an applicable conversion ratio of 0.45853 upon the closing of the Issuer's initial public offering on December 11, 2018. The Series C Preferred Stock had no expiration date.

F1 · ownership.nature: Shares held by Flagship Ventures Fund IV, L.P. ("Flagship Fund IV"). Flagship Ventures Fund IV General Partner LLC ("Flagship Fund IV GP") is the general partner of Flagship Fund IV. Noubar B. Afeyan, Ph.D. and Edwin M. Kania, Jr. are the managers of Flagship Fund IV GP. While Mr. Kania is retired from Flagship Pioneering, Inc. ("Pioneering"), he continues to serve as a manager of Flagship Fund IV GP. Each of the reporting persons except for Flagship Fund IV disclaims beneficial ownership of such shares except to the extent of his or its pecuniary interest therein.

SEC source: 0000899243-18-030859 · doc4.xml · derivative · entry 14

AFEYAN NOUBAR · CIK 0001222012 · Director · 10% owner

Flagship Ventures Fund IV General Partner LLC · CIK 0001508051 · 10% owner

Flagship Pioneering Inc. · CIK 0001400240 · 10% owner

Flagship VentureLabs IV, LLC · CIK 0001642578 · 10% owner

Flagship Ventures Fund IV, L.P. · CIK 0001503559 · 10% owner

Flagship Ventures Fund IV-Rx, L.P. · CIK 0001590973 · 10% owner

KANIA EDWIN M JR · CIK 0001255927 · 10% owner

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

10b5-1 filing: Not disclosed

Ownership: Indirect · By: Flagship Ventures Fund IV-Rx, LP

Disclosed balance after: 0

Underlying: Common Stock · 6,195,632 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.

F6 · derivative.exercise_price: The Series B Preferred Stock converted into Common Stock based on an applicable conversion ratio of 0.45457 upon the closing of the Issuer's initial public offering on December 11, 2018. The Series B Preferred Stock had no expiration date.

F6 · price: The Series B Preferred Stock converted into Common Stock based on an applicable conversion ratio of 0.45457 upon the closing of the Issuer's initial public offering on December 11, 2018. The Series B Preferred Stock had no expiration date.

F6 · derivative.exercise_date: The Series B Preferred Stock converted into Common Stock based on an applicable conversion ratio of 0.45457 upon the closing of the Issuer's initial public offering on December 11, 2018. The Series B Preferred Stock had no expiration date.

F6 · derivative.expiration_date: The Series B Preferred Stock converted into Common Stock based on an applicable conversion ratio of 0.45457 upon the closing of the Issuer's initial public offering on December 11, 2018. The Series B Preferred Stock had no expiration date.

F2 · ownership.nature: Shares held by Flagship Ventures Fund IV-Rx, L.P. ("Flagship Fund IV-Rx"). Flagship Fund IV GP is the general partner of Flagship Fund IV-Rx. While Mr. Kania is retired from Pioneering he continues to serve as a manager of the Flagship Fund IV GP. Each of the reporting persons except for Flagship Fund IV-Rx disclaims beneficial ownership of such shares except to the extent of his or its pecuniary interest therein.

SEC source: 0000899243-18-030859 · doc4.xml · derivative · entry 13

AFEYAN NOUBAR · CIK 0001222012 · Director · 10% owner

Flagship Ventures Fund IV General Partner LLC · CIK 0001508051 · 10% owner

Flagship Pioneering Inc. · CIK 0001400240 · 10% owner

Flagship VentureLabs IV, LLC · CIK 0001642578 · 10% owner

Flagship Ventures Fund IV, L.P. · CIK 0001503559 · 10% owner

Flagship Ventures Fund IV-Rx, L.P. · CIK 0001590973 · 10% owner

KANIA EDWIN M JR · CIK 0001255927 · 10% owner

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

10b5-1 filing: Not disclosed

Ownership: Indirect · By: Flagship Ventures Fund IV, LP

Disclosed balance after: 0

Underlying: Common Stock · 24,782,551 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.

F6 · derivative.exercise_price: The Series B Preferred Stock converted into Common Stock based on an applicable conversion ratio of 0.45457 upon the closing of the Issuer's initial public offering on December 11, 2018. The Series B Preferred Stock had no expiration date.

F6 · price: The Series B Preferred Stock converted into Common Stock based on an applicable conversion ratio of 0.45457 upon the closing of the Issuer's initial public offering on December 11, 2018. The Series B Preferred Stock had no expiration date.

F6 · derivative.exercise_date: The Series B Preferred Stock converted into Common Stock based on an applicable conversion ratio of 0.45457 upon the closing of the Issuer's initial public offering on December 11, 2018. The Series B Preferred Stock had no expiration date.

F6 · derivative.expiration_date: The Series B Preferred Stock converted into Common Stock based on an applicable conversion ratio of 0.45457 upon the closing of the Issuer's initial public offering on December 11, 2018. The Series B Preferred Stock had no expiration date.

F1 · ownership.nature: Shares held by Flagship Ventures Fund IV, L.P. ("Flagship Fund IV"). Flagship Ventures Fund IV General Partner LLC ("Flagship Fund IV GP") is the general partner of Flagship Fund IV. Noubar B. Afeyan, Ph.D. and Edwin M. Kania, Jr. are the managers of Flagship Fund IV GP. While Mr. Kania is retired from Flagship Pioneering, Inc. ("Pioneering"), he continues to serve as a manager of Flagship Fund IV GP. Each of the reporting persons except for Flagship Fund IV disclaims beneficial ownership of such shares except to the extent of his or its pecuniary interest therein.

SEC source: 0000899243-18-030859 · doc4.xml · derivative · entry 12

AFEYAN NOUBAR · CIK 0001222012 · Director · 10% owner

Flagship Ventures Fund IV General Partner LLC · CIK 0001508051 · 10% owner

Flagship Pioneering Inc. · CIK 0001400240 · 10% owner

Flagship VentureLabs IV, LLC · CIK 0001642578 · 10% owner

Flagship Ventures Fund IV, L.P. · CIK 0001503559 · 10% owner

Flagship Ventures Fund IV-Rx, L.P. · CIK 0001590973 · 10% owner

KANIA EDWIN M JR · CIK 0001255927 · 10% owner

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

10b5-1 filing: Not disclosed

Ownership: Indirect · By: Flagship Ventures Fund IV-Rx, LP

Disclosed balance after: 0

Underlying: Common Stock · 1,823,036 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.

F5 · derivative.exercise_price: The Series A Preferred Stock converted into shares of the Issuer's common stock, $0.0001 par value per share ("Common Stock") based on an applicable conversion ratio of 0.45576 upon the closing of the Issuer's initial public offering on December 11, 2018. The Series A Preferred Stock had no expiration date.

F5 · price: The Series A Preferred Stock converted into shares of the Issuer's common stock, $0.0001 par value per share ("Common Stock") based on an applicable conversion ratio of 0.45576 upon the closing of the Issuer's initial public offering on December 11, 2018. The Series A Preferred Stock had no expiration date.

F5 · derivative.exercise_date: The Series A Preferred Stock converted into shares of the Issuer's common stock, $0.0001 par value per share ("Common Stock") based on an applicable conversion ratio of 0.45576 upon the closing of the Issuer's initial public offering on December 11, 2018. The Series A Preferred Stock had no expiration date.

F5 · derivative.expiration_date: The Series A Preferred Stock converted into shares of the Issuer's common stock, $0.0001 par value per share ("Common Stock") based on an applicable conversion ratio of 0.45576 upon the closing of the Issuer's initial public offering on December 11, 2018. The Series A Preferred Stock had no expiration date.

F2 · ownership.nature: Shares held by Flagship Ventures Fund IV-Rx, L.P. ("Flagship Fund IV-Rx"). Flagship Fund IV GP is the general partner of Flagship Fund IV-Rx. While Mr. Kania is retired from Pioneering he continues to serve as a manager of the Flagship Fund IV GP. Each of the reporting persons except for Flagship Fund IV-Rx disclaims beneficial ownership of such shares except to the extent of his or its pecuniary interest therein.

SEC source: 0000899243-18-030859 · doc4.xml · derivative · entry 11

AFEYAN NOUBAR · CIK 0001222012 · Director · 10% owner

Flagship Ventures Fund IV General Partner LLC · CIK 0001508051 · 10% owner

Flagship Pioneering Inc. · CIK 0001400240 · 10% owner

Flagship VentureLabs IV, LLC · CIK 0001642578 · 10% owner

Flagship Ventures Fund IV, L.P. · CIK 0001503559 · 10% owner

Flagship Ventures Fund IV-Rx, L.P. · CIK 0001590973 · 10% owner

KANIA EDWIN M JR · CIK 0001255927 · 10% owner

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

10b5-1 filing: Not disclosed

Ownership: Indirect · By: Flagship Ventures Fund IV, LP

Disclosed balance after: 0

Underlying: Common Stock · 7,292,145 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.

F5 · derivative.exercise_price: The Series A Preferred Stock converted into shares of the Issuer's common stock, $0.0001 par value per share ("Common Stock") based on an applicable conversion ratio of 0.45576 upon the closing of the Issuer's initial public offering on December 11, 2018. The Series A Preferred Stock had no expiration date.

F5 · price: The Series A Preferred Stock converted into shares of the Issuer's common stock, $0.0001 par value per share ("Common Stock") based on an applicable conversion ratio of 0.45576 upon the closing of the Issuer's initial public offering on December 11, 2018. The Series A Preferred Stock had no expiration date.

F5 · derivative.exercise_date: The Series A Preferred Stock converted into shares of the Issuer's common stock, $0.0001 par value per share ("Common Stock") based on an applicable conversion ratio of 0.45576 upon the closing of the Issuer's initial public offering on December 11, 2018. The Series A Preferred Stock had no expiration date.

F5 · derivative.expiration_date: The Series A Preferred Stock converted into shares of the Issuer's common stock, $0.0001 par value per share ("Common Stock") based on an applicable conversion ratio of 0.45576 upon the closing of the Issuer's initial public offering on December 11, 2018. The Series A Preferred Stock had no expiration date.

F1 · ownership.nature: Shares held by Flagship Ventures Fund IV, L.P. ("Flagship Fund IV"). Flagship Ventures Fund IV General Partner LLC ("Flagship Fund IV GP") is the general partner of Flagship Fund IV. Noubar B. Afeyan, Ph.D. and Edwin M. Kania, Jr. are the managers of Flagship Fund IV GP. While Mr. Kania is retired from Flagship Pioneering, Inc. ("Pioneering"), he continues to serve as a manager of Flagship Fund IV GP. Each of the reporting persons except for Flagship Fund IV disclaims beneficial ownership of such shares except to the extent of his or its pecuniary interest therein.

SEC source: 0000899243-18-030859 · doc4.xml · nonDerivative · entry 8

AFEYAN NOUBAR · CIK 0001222012 · Director · 10% owner

Flagship Ventures Fund IV General Partner LLC · CIK 0001508051 · 10% owner

Flagship Pioneering Inc. · CIK 0001400240 · 10% owner

Flagship VentureLabs IV, LLC · CIK 0001642578 · 10% owner

Flagship Ventures Fund IV, L.P. · CIK 0001503559 · 10% owner

Flagship Ventures Fund IV-Rx, L.P. · CIK 0001590973 · 10% owner

KANIA EDWIN M JR · CIK 0001255927 · 10% owner

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

10b5-1 filing: Not disclosed

Ownership: Indirect · By: Flagship Ventures Fund IV-Rx, LP

Disclosed balance after: 9,468,596

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.

F8 · price: The Series D Preferred Stock converted into Common Stock based on an applicable conversion ratio of 0.45854 upon the closing of the Issuer's initial public offering on December 11, 2018. The Series D Preferred Stock had no expiration date.

F2 · ownership.nature: Shares held by Flagship Ventures Fund IV-Rx, L.P. ("Flagship Fund IV-Rx"). Flagship Fund IV GP is the general partner of Flagship Fund IV-Rx. While Mr. Kania is retired from Pioneering he continues to serve as a manager of the Flagship Fund IV GP. Each of the reporting persons except for Flagship Fund IV-Rx disclaims beneficial ownership of such shares except to the extent of his or its pecuniary interest therein.

SEC source: 0000899243-18-030859 · doc4.xml · nonDerivative · entry 7

AFEYAN NOUBAR · CIK 0001222012 · Director · 10% owner

Flagship Ventures Fund IV General Partner LLC · CIK 0001508051 · 10% owner

Flagship Pioneering Inc. · CIK 0001400240 · 10% owner

Flagship VentureLabs IV, LLC · CIK 0001642578 · 10% owner

Flagship Ventures Fund IV, L.P. · CIK 0001503559 · 10% owner

Flagship Ventures Fund IV-Rx, L.P. · CIK 0001590973 · 10% owner

KANIA EDWIN M JR · CIK 0001255927 · 10% owner

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

10b5-1 filing: Not disclosed

Ownership: Indirect · By: Flagship Ventures Fund IV, LP

Disclosed balance after: 37,874,424

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.

F8 · price: The Series D Preferred Stock converted into Common Stock based on an applicable conversion ratio of 0.45854 upon the closing of the Issuer's initial public offering on December 11, 2018. The Series D Preferred Stock had no expiration date.

F1 · ownership.nature: Shares held by Flagship Ventures Fund IV, L.P. ("Flagship Fund IV"). Flagship Ventures Fund IV General Partner LLC ("Flagship Fund IV GP") is the general partner of Flagship Fund IV. Noubar B. Afeyan, Ph.D. and Edwin M. Kania, Jr. are the managers of Flagship Fund IV GP. While Mr. Kania is retired from Flagship Pioneering, Inc. ("Pioneering"), he continues to serve as a manager of Flagship Fund IV GP. Each of the reporting persons except for Flagship Fund IV disclaims beneficial ownership of such shares except to the extent of his or its pecuniary interest therein.

SEC source: 0000899243-18-030859 · doc4.xml · nonDerivative · entry 6

AFEYAN NOUBAR · CIK 0001222012 · Director · 10% owner

Flagship Ventures Fund IV General Partner LLC · CIK 0001508051 · 10% owner

Flagship Pioneering Inc. · CIK 0001400240 · 10% owner

Flagship VentureLabs IV, LLC · CIK 0001642578 · 10% owner

Flagship Ventures Fund IV, L.P. · CIK 0001503559 · 10% owner

Flagship Ventures Fund IV-Rx, L.P. · CIK 0001590973 · 10% owner

KANIA EDWIN M JR · CIK 0001255927 · 10% owner

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

10b5-1 filing: Not disclosed

Ownership: Indirect · By: Flagship Ventures Fund IV-Rx, LP

Disclosed balance after: 9,447,100

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.

F7 · price: The Series C Preferred Stock converted into Common Stock based on an applicable conversion ratio of 0.45853 upon the closing of the Issuer's initial public offering on December 11, 2018. The Series C Preferred Stock had no expiration date.

F2 · ownership.nature: Shares held by Flagship Ventures Fund IV-Rx, L.P. ("Flagship Fund IV-Rx"). Flagship Fund IV GP is the general partner of Flagship Fund IV-Rx. While Mr. Kania is retired from Pioneering he continues to serve as a manager of the Flagship Fund IV GP. Each of the reporting persons except for Flagship Fund IV-Rx disclaims beneficial ownership of such shares except to the extent of his or its pecuniary interest therein.

SEC source: 0000899243-18-030859 · doc4.xml · nonDerivative · entry 5

AFEYAN NOUBAR · CIK 0001222012 · Director · 10% owner

Flagship Ventures Fund IV General Partner LLC · CIK 0001508051 · 10% owner

Flagship Pioneering Inc. · CIK 0001400240 · 10% owner

Flagship VentureLabs IV, LLC · CIK 0001642578 · 10% owner

Flagship Ventures Fund IV, L.P. · CIK 0001503559 · 10% owner

Flagship Ventures Fund IV-Rx, L.P. · CIK 0001590973 · 10% owner

KANIA EDWIN M JR · CIK 0001255927 · 10% owner

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

10b5-1 filing: Not disclosed

Ownership: Indirect · By: Flagship Ventures Fund IV, LP

Disclosed balance after: 37,788,435

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.

F7 · price: The Series C Preferred Stock converted into Common Stock based on an applicable conversion ratio of 0.45853 upon the closing of the Issuer's initial public offering on December 11, 2018. The Series C Preferred Stock had no expiration date.

F1 · ownership.nature: Shares held by Flagship Ventures Fund IV, L.P. ("Flagship Fund IV"). Flagship Ventures Fund IV General Partner LLC ("Flagship Fund IV GP") is the general partner of Flagship Fund IV. Noubar B. Afeyan, Ph.D. and Edwin M. Kania, Jr. are the managers of Flagship Fund IV GP. While Mr. Kania is retired from Flagship Pioneering, Inc. ("Pioneering"), he continues to serve as a manager of Flagship Fund IV GP. Each of the reporting persons except for Flagship Fund IV disclaims beneficial ownership of such shares except to the extent of his or its pecuniary interest therein.

SEC source: 0000899243-18-030859 · doc4.xml · nonDerivative · entry 4

AFEYAN NOUBAR · CIK 0001222012 · Director · 10% owner

Flagship Ventures Fund IV General Partner LLC · CIK 0001508051 · 10% owner

Flagship Pioneering Inc. · CIK 0001400240 · 10% owner

Flagship VentureLabs IV, LLC · CIK 0001642578 · 10% owner

Flagship Ventures Fund IV, L.P. · CIK 0001503559 · 10% owner

Flagship Ventures Fund IV-Rx, L.P. · CIK 0001590973 · 10% owner

KANIA EDWIN M JR · CIK 0001255927 · 10% owner

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

10b5-1 filing: Not disclosed

Ownership: Indirect · By: Flagship Ventures Fund IV-Rx, LP

Disclosed balance after: 8,018,668

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.

F6 · price: The Series B Preferred Stock converted into Common Stock based on an applicable conversion ratio of 0.45457 upon the closing of the Issuer's initial public offering on December 11, 2018. The Series B Preferred Stock had no expiration date.

F2 · ownership.nature: Shares held by Flagship Ventures Fund IV-Rx, L.P. ("Flagship Fund IV-Rx"). Flagship Fund IV GP is the general partner of Flagship Fund IV-Rx. While Mr. Kania is retired from Pioneering he continues to serve as a manager of the Flagship Fund IV GP. Each of the reporting persons except for Flagship Fund IV-Rx disclaims beneficial ownership of such shares except to the extent of his or its pecuniary interest therein.

SEC source: 0000899243-18-030859 · doc4.xml · nonDerivative · entry 3

AFEYAN NOUBAR · CIK 0001222012 · Director · 10% owner

Flagship Ventures Fund IV General Partner LLC · CIK 0001508051 · 10% owner

Flagship Pioneering Inc. · CIK 0001400240 · 10% owner

Flagship VentureLabs IV, LLC · CIK 0001642578 · 10% owner

Flagship Ventures Fund IV, L.P. · CIK 0001503559 · 10% owner

Flagship Ventures Fund IV-Rx, L.P. · CIK 0001590973 · 10% owner

KANIA EDWIN M JR · CIK 0001255927 · 10% owner

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

10b5-1 filing: Not disclosed

Ownership: Indirect · By: Flagship Ventures Fund IV, LP

Disclosed balance after: 32,074,696

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.

F6 · price: The Series B Preferred Stock converted into Common Stock based on an applicable conversion ratio of 0.45457 upon the closing of the Issuer's initial public offering on December 11, 2018. The Series B Preferred Stock had no expiration date.

F1 · ownership.nature: Shares held by Flagship Ventures Fund IV, L.P. ("Flagship Fund IV"). Flagship Ventures Fund IV General Partner LLC ("Flagship Fund IV GP") is the general partner of Flagship Fund IV. Noubar B. Afeyan, Ph.D. and Edwin M. Kania, Jr. are the managers of Flagship Fund IV GP. While Mr. Kania is retired from Flagship Pioneering, Inc. ("Pioneering"), he continues to serve as a manager of Flagship Fund IV GP. Each of the reporting persons except for Flagship Fund IV disclaims beneficial ownership of such shares except to the extent of his or its pecuniary interest therein.

SEC source: 0000899243-18-030859 · doc4.xml · nonDerivative · entry 2

AFEYAN NOUBAR · CIK 0001222012 · Director · 10% owner

Flagship Ventures Fund IV General Partner LLC · CIK 0001508051 · 10% owner

Flagship Pioneering Inc. · CIK 0001400240 · 10% owner

Flagship VentureLabs IV, LLC · CIK 0001642578 · 10% owner

Flagship Ventures Fund IV, L.P. · CIK 0001503559 · 10% owner

Flagship Ventures Fund IV-Rx, L.P. · CIK 0001590973 · 10% owner

KANIA EDWIN M JR · CIK 0001255927 · 10% owner

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

10b5-1 filing: Not disclosed

Ownership: Indirect · By: Flagship Ventures Fund IV-Rx, LP

Disclosed balance after: 1,823,036

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.

F5 · price: The Series A Preferred Stock converted into shares of the Issuer's common stock, $0.0001 par value per share ("Common Stock") based on an applicable conversion ratio of 0.45576 upon the closing of the Issuer's initial public offering on December 11, 2018. The Series A Preferred Stock had no expiration date.

F2 · ownership.nature: Shares held by Flagship Ventures Fund IV-Rx, L.P. ("Flagship Fund IV-Rx"). Flagship Fund IV GP is the general partner of Flagship Fund IV-Rx. While Mr. Kania is retired from Pioneering he continues to serve as a manager of the Flagship Fund IV GP. Each of the reporting persons except for Flagship Fund IV-Rx disclaims beneficial ownership of such shares except to the extent of his or its pecuniary interest therein.

SEC source: 0000899243-18-030859 · doc4.xml · nonDerivative · entry 1

AFEYAN NOUBAR · CIK 0001222012 · Director · 10% owner

Flagship Ventures Fund IV General Partner LLC · CIK 0001508051 · 10% owner

Flagship Pioneering Inc. · CIK 0001400240 · 10% owner

Flagship VentureLabs IV, LLC · CIK 0001642578 · 10% owner

Flagship Ventures Fund IV, L.P. · CIK 0001503559 · 10% owner

Flagship Ventures Fund IV-Rx, L.P. · CIK 0001590973 · 10% owner

KANIA EDWIN M JR · CIK 0001255927 · 10% owner

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

10b5-1 filing: Not disclosed

Ownership: Indirect · By: Flagship Ventures Fund IV, LP

Disclosed balance after: 7,292,145

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.

F5 · price: The Series A Preferred Stock converted into shares of the Issuer's common stock, $0.0001 par value per share ("Common Stock") based on an applicable conversion ratio of 0.45576 upon the closing of the Issuer's initial public offering on December 11, 2018. The Series A Preferred Stock had no expiration date.

F1 · ownership.nature: Shares held by Flagship Ventures Fund IV, L.P. ("Flagship Fund IV"). Flagship Ventures Fund IV General Partner LLC ("Flagship Fund IV GP") is the general partner of Flagship Fund IV. Noubar B. Afeyan, Ph.D. and Edwin M. Kania, Jr. are the managers of Flagship Fund IV GP. While Mr. Kania is retired from Flagship Pioneering, Inc. ("Pioneering"), he continues to serve as a manager of Flagship Fund IV GP. Each of the reporting persons except for Flagship Fund IV disclaims beneficial ownership of such shares except to the extent of his or its pecuniary interest therein.

SEC source: 0000899243-18-030858 · doc4.xml · derivative · entry 16

Bancel Stephane · CIK 0001443340 · Director · Chief Executive Officer

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 0

Underlying: Common Stock · 22,935 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.

F9 · derivative.exercise_price: The Series G Preferred Stock converted into Common Stock based on an applicable conversion ratio of 0.45872 upon the closing of the Issuer's initial public offering on December 11, 2018. The Series G Preferred Stock had no expiration date.

F9 · price: The Series G Preferred Stock converted into Common Stock based on an applicable conversion ratio of 0.45872 upon the closing of the Issuer's initial public offering on December 11, 2018. The Series G Preferred Stock had no expiration date.

F9 · derivative.exercise_date: The Series G Preferred Stock converted into Common Stock based on an applicable conversion ratio of 0.45872 upon the closing of the Issuer's initial public offering on December 11, 2018. The Series G Preferred Stock had no expiration date.

F9 · derivative.expiration_date: The Series G Preferred Stock converted into Common Stock based on an applicable conversion ratio of 0.45872 upon the closing of the Issuer's initial public offering on December 11, 2018. The Series G Preferred Stock had no expiration date.

F2 · ownership.nature: These shares are owned directly by OCHA LLC ("OCHA"). The reporting person is the majority equity unit holder and the sole managing member of OCHA. The reporting person disclaims Section 16 beneficial ownership of these securities, except to the extent of his pecuniary interest therein, if any, and this report shall not be deemed an admission that the reporting person is the beneficial owner of such securities for Section 16 or any other purpose.

SEC source: 0000899243-18-030858 · doc4.xml · derivative · entry 15

Bancel Stephane · CIK 0001443340 · Director · Chief Executive Officer

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 0

Underlying: Common Stock · 4,587 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.

F8 · derivative.exercise_price: The Series F Preferred Stock converted into Common Stock based on an applicable conversion ratio of 0.45872 upon the closing of the Issuer's initial public offering on December 11, 2018. The Series F Preferred Stock had no expiration date.

F8 · price: The Series F Preferred Stock converted into Common Stock based on an applicable conversion ratio of 0.45872 upon the closing of the Issuer's initial public offering on December 11, 2018. The Series F Preferred Stock had no expiration date.

F8 · derivative.exercise_date: The Series F Preferred Stock converted into Common Stock based on an applicable conversion ratio of 0.45872 upon the closing of the Issuer's initial public offering on December 11, 2018. The Series F Preferred Stock had no expiration date.

F8 · derivative.expiration_date: The Series F Preferred Stock converted into Common Stock based on an applicable conversion ratio of 0.45872 upon the closing of the Issuer's initial public offering on December 11, 2018. The Series F Preferred Stock had no expiration date.

F4 · ownership.nature: These shares are owned directly by Boston Biotech Ventures, LLC ("Boston Biotech"). The reporting person is the majority equity unit holder and the sole managing member of Boston Biotech. The reporting person disclaims Section 16 beneficial ownership of these securities, except to the extent of his pecuniary interest therein, if any, and this report shall not be deemed an admission that the reporting person is the beneficial owner of such securities for Section 16 or any other purpose.

SEC source: 0000899243-18-030858 · doc4.xml · derivative · entry 14

Bancel Stephane · CIK 0001443340 · Director · Chief Executive Officer

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 0

Underlying: Common Stock · 18,591 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.

F7 · derivative.exercise_price: The Series E Preferred Stock converted into Common Stock based on an applicable conversion ratio of 0.45859 upon the closing of the Issuer's initial public offering on December 11, 2018. The Series E Preferred Stock had no expiration date.

F7 · price: The Series E Preferred Stock converted into Common Stock based on an applicable conversion ratio of 0.45859 upon the closing of the Issuer's initial public offering on December 11, 2018. The Series E Preferred Stock had no expiration date.

F7 · derivative.exercise_date: The Series E Preferred Stock converted into Common Stock based on an applicable conversion ratio of 0.45859 upon the closing of the Issuer's initial public offering on December 11, 2018. The Series E Preferred Stock had no expiration date.

F7 · derivative.expiration_date: The Series E Preferred Stock converted into Common Stock based on an applicable conversion ratio of 0.45859 upon the closing of the Issuer's initial public offering on December 11, 2018. The Series E Preferred Stock had no expiration date.

F4 · ownership.nature: These shares are owned directly by Boston Biotech Ventures, LLC ("Boston Biotech"). The reporting person is the majority equity unit holder and the sole managing member of Boston Biotech. The reporting person disclaims Section 16 beneficial ownership of these securities, except to the extent of his pecuniary interest therein, if any, and this report shall not be deemed an admission that the reporting person is the beneficial owner of such securities for Section 16 or any other purpose.