SEPN

SEC source: 0001193125-26-388033 · ownership.xml · derivative · entry 1

Patni Rajiv · CIK 0001616200 · Chief Medical Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 275,000

Underlying: Common Stock · 275,000 shares

Expires 2036-09-07

F1 · derivative.exercise_date: 25% of the shares underlying this option will vest on August 24, 2027, and the remaining 75% of the shares underlying this option will vest in thirty-six substantially equal monthly installments thereafter, subject to the Reporting Person's continuous service to the Issuer on each such vesting date.

SEC source: 0001193125-26-382267 · ownership.xml · derivative · entry 3

Long Daniel D. · CIK 0002040349 · SVP, Drug Discovery

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 9,085

Underlying: Common Stock · 3,333 shares

Expires 2034-03-19

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_date: 1/48th of the shares subject to such option shall vest and become exercisable in substantially equal monthly installments on each monthly anniversary of March 1, 2024, subject to the Reporting Person's continuous service to the Issuer on each such date.

SEC source: 0001193125-26-382267 · ownership.xml · nonDerivative · entry 2

Long Daniel D. · CIK 0002040349 · SVP, Drug Discovery

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 96,412

F1 · kind: This transaction was effected pursuant to a Rule 10b5-1 sales plan adopted by the Reporting Person on March 20, 2026.

F2 · price: The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $37.34 to $38.21. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

SEC source: 0001193125-26-382267 · ownership.xml · nonDerivative · entry 1

Long Daniel D. · CIK 0002040349 · SVP, Drug Discovery

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 99,745

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: 0001193125-26-352692 · ownership.xml · nonDerivative · entry 2

Third Rock Ventures V, L.P. · CIK 0001778071 · 10% owner

Third Rock Ventures GP V, LP · CIK 0001977498 · 10% owner

TRV GP V, LLC · CIK 0001990717 · 10% owner

Third Rock Ventures VI, L.P. · CIK 0001931056 · 10% owner

Third Rock Ventures GP VI, L.P. · CIK 0001977499 · 10% owner

TRV GP VI, LLC · CIK 0001990716 · 10% owner

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

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 6,068,391

F1 · kind: The reported transactions were effected pursuant to a Rule 10b5-1 trading plan dated March 26, 2026, previously adopted by the Reporting Person.

F4 · price: The price reported is a weighted average price. These shares were sold in multiple transactions at prices ranging from $51.00 to $51.10, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote (4).

F3 · ownership.direct: These shares are directly held by Third Rock Ventures V, L.P. ("TRV V"). The general partner of TRV V is Third Rock Ventures GP V, L.P. ("TRV GP V"). The general partner of TRV GP V is TRV GP V, LLC ("TRV GP V LLC"). Each of TRV GP V and TRV GP V LLC disclaims beneficial ownership of the 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: 0001193125-26-352692 · ownership.xml · nonDerivative · entry 1

Third Rock Ventures V, L.P. · CIK 0001778071 · 10% owner

Third Rock Ventures GP V, LP · CIK 0001977498 · 10% owner

TRV GP V, LLC · CIK 0001990717 · 10% owner

Third Rock Ventures VI, L.P. · CIK 0001931056 · 10% owner

Third Rock Ventures GP VI, L.P. · CIK 0001977499 · 10% owner

TRV GP VI, LLC · CIK 0001990716 · 10% owner

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

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 6,068,532

F1 · kind: The reported transactions were effected pursuant to a Rule 10b5-1 trading plan dated March 26, 2026, previously adopted by the Reporting Person.

F2 · price: The price reported is a weighted average price. These shares were sold in multiple transactions at prices ranging from $50.05 to $50.81, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote (2).

F3 · ownership.direct: These shares are directly held by Third Rock Ventures V, L.P. ("TRV V"). The general partner of TRV V is Third Rock Ventures GP V, L.P. ("TRV GP V"). The general partner of TRV GP V is TRV GP V, LLC ("TRV GP V LLC"). Each of TRV GP V and TRV GP V LLC disclaims beneficial ownership of the 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: 0001231919-26-000938 · form4-08142026_090829.xml · nonDerivative · entry 2

RA CAPITAL MANAGEMENT, L.P. · CIK 0001346824 · Director · 10% owner

RA Capital Healthcare Fund LP · CIK 0001315082 · Director · 10% owner

RA Capital Nexus Fund III, L.P. · CIK 0001883840 · Director

Kolchinsky Peter · CIK 0001384859 · Director · 10% owner

Shah Rajeev M. · CIK 0001619841 · Director · 10% owner

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

10b5-1 filing: No plan indicated

Ownership: Indirect · See footnotes

Disclosed balance after: 725,443

F1 · ownership.nature: RA Capital Management, L.P. (the "Adviser") is the investment manager for RA Capital Healthcare Fund, L.P. (the "Fund") and RA Capital Nexus Fund III, L.P. (the "Nexus Fund III"). The general partner of the Adviser is RA Capital Management GP, LLC (the "Adviser GP"), of which Dr. Peter Kolchinsky and Mr. Rajeev Shah are the managing members. Each of the Adviser, the Adviser GP, the Fund, the Nexus Fund III, Dr. Kolchinsky and Mr. Shah disclaims beneficial ownership of any of the reported securities, except to the extent of its or his respective pecuniary interest therein.

F3 · ownership.nature: Held directly by the Nexus Fund III.

SEC source: 0001231919-26-000938 · form4-08142026_090829.xml · nonDerivative · entry 1

RA CAPITAL MANAGEMENT, L.P. · CIK 0001346824 · Director · 10% owner

RA Capital Healthcare Fund LP · CIK 0001315082 · Director · 10% owner

RA Capital Nexus Fund III, L.P. · CIK 0001883840 · Director

Kolchinsky Peter · CIK 0001384859 · Director · 10% owner

Shah Rajeev M. · CIK 0001619841 · Director · 10% owner

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

10b5-1 filing: No plan indicated

Ownership: Indirect · See footnotes

Disclosed balance after: 4,777,415

F1 · ownership.nature: RA Capital Management, L.P. (the "Adviser") is the investment manager for RA Capital Healthcare Fund, L.P. (the "Fund") and RA Capital Nexus Fund III, L.P. (the "Nexus Fund III"). The general partner of the Adviser is RA Capital Management GP, LLC (the "Adviser GP"), of which Dr. Peter Kolchinsky and Mr. Rajeev Shah are the managing members. Each of the Adviser, the Adviser GP, the Fund, the Nexus Fund III, Dr. Kolchinsky and Mr. Shah disclaims beneficial ownership of any of the reported securities, except to the extent of its or his respective pecuniary interest therein.

F2 · ownership.nature: Held directly by the Fund.

SEC source: 0001193125-26-349810 · ownership.xml · derivative · entry 5

Bhatt Elizabeth · CIK 0001748622 · President and COO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 82,332

Underlying: Common Stock · 6,319 shares

Expires 2033-11-11

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_date: 1/48th of the shares subject to such option vest and become exercisable in substantially equal monthly installments on each monthly anniversary of August 1, 2023, subject to the Reporting Person's continuous service to the Issuer on each such date.

SEC source: 0001193125-26-349810 · ownership.xml · derivative · entry 4

Bhatt Elizabeth · CIK 0001748622 · President and COO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 62,230

Underlying: Common Stock · 18,681 shares

Expires 2034-09-22

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: 1/48th of the shares subject to such option vest and become exercisable in substantially equal monthly installments on each monthly anniversary of October 28, 2024, subject to the Reporting Person's continuous service to the Issuer on each such date.

SEC source: 0001193125-26-349810 · ownership.xml · nonDerivative · entry 3

Bhatt Elizabeth · CIK 0001748622 · President and COO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 174,209

F1 · kind: This transaction was effected pursuant to a Rule 10b5-1 sales plan adopted by the Reporting Person on October 20, 2025.

SEC source: 0001193125-26-349810 · ownership.xml · nonDerivative · entry 2

Bhatt Elizabeth · CIK 0001748622 · President and COO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 199,209

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: 0001193125-26-349810 · ownership.xml · nonDerivative · entry 1

Bhatt Elizabeth · CIK 0001748622 · President and COO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 192,890

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: 0001193125-26-335820 · ownership.xml · derivative · entry 6

Long Daniel D. · CIK 0002040349 · SVP, Drug Discovery

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 12,418

Underlying: Common Stock · 1,518 shares

Expires 2034-03-19

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_date: 1/48th of the shares subject to such option shall vest and become exercisable in substantially equal monthly installments on each monthly anniversary of March 1, 2024, subject to the Reporting Person's continuous service to the Issuer on each such date.

SEC source: 0001193125-26-335820 · ownership.xml · derivative · entry 5

Long Daniel D. · CIK 0002040349 · SVP, Drug Discovery

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 5,227

Underlying: Common Stock · 1,816 shares

Expires 2033-11-11

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.

F4 · derivative.exercise_date: 1/48th of the shares subject to such option shall vest and become exercisable in substantially equal monthly installments on each monthly anniversary of August 1, 2023, subject to the Reporting Person's continuous service to the Issuer on each such date.

SEC source: 0001193125-26-335820 · ownership.xml · nonDerivative · entry 4

Long Daniel D. · CIK 0002040349 · SVP, Drug Discovery

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 96,412

F1 · kind: This transaction was effected pursuant to a Rule 10b5-1 sales plan adopted by the Reporting Person on March 20, 2026.

F3 · price: The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $34.43 to $35.04. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

SEC source: 0001193125-26-335820 · ownership.xml · nonDerivative · entry 3

Long Daniel D. · CIK 0002040349 · SVP, Drug Discovery

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 98,746

F1 · kind: This transaction was effected pursuant to a Rule 10b5-1 sales plan adopted by the Reporting Person on March 20, 2026.

F2 · price: The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $33.39 to $34.32. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

SEC source: 0001193125-26-335820 · ownership.xml · nonDerivative · entry 2

Long Daniel D. · CIK 0002040349 · SVP, Drug Discovery

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 99,746

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: 0001193125-26-335820 · ownership.xml · nonDerivative · entry 1

Long Daniel D. · CIK 0002040349 · SVP, Drug Discovery

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 98,228

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: 0001193125-26-308073 · ownership.xml · derivative · entry 3

Bhatt Elizabeth · CIK 0001748622 · President and COO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 80,911

Underlying: Common Stock · 4,000 shares

Expires 2034-09-22

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_date: 1/48th of the shares subject to such option vest and become exercisable in substantially equal monthly installments on each monthly anniversary of October 28, 2024, subject to the Reporting Person's continuous service to the Issuer on each such date.

SEC source: 0001193125-26-308073 · ownership.xml · nonDerivative · entry 2

Bhatt Elizabeth · CIK 0001748622 · President and COO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 174,209

F1 · kind: This transaction was effected pursuant to a Rule 10b5-1 sales plan adopted by the Reporting Person on October 20, 2025.

F2 · price: The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $33.49 to $34.24. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

SEC source: 0001193125-26-308073 · ownership.xml · nonDerivative · entry 1

Bhatt Elizabeth · CIK 0001748622 · President and COO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 178,209

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: 0001193125-26-295106 · ownership.xml · derivative · entry 4

Long Daniel D. · CIK 0002040349 · SVP, Drug Discovery

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 7,043

Underlying: Common Stock · 3,333 shares

Expires 2033-11-11

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.

F4 · derivative.exercise_date: 1/48th of the shares subject to such option vest and become exercisable in substantially equal monthly installments on each monthly anniversary of August 1, 2023, subject to the Reporting Person's continuous service to the Issuer on each such date.

SEC source: 0001193125-26-295106 · ownership.xml · nonDerivative · entry 3

Long Daniel D. · CIK 0002040349 · SVP, Drug Discovery

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 96,412

F1 · kind: This transaction was effected pursuant to a Rule 10b5-1 sales plan adopted by the Reporting Person on March 20, 2026.

F3 · price: The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $34.52 to $35.10. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

SEC source: 0001193125-26-295106 · ownership.xml · nonDerivative · entry 2

Long Daniel D. · CIK 0002040349 · SVP, Drug Discovery

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 97,645

F1 · kind: This transaction was effected pursuant to a Rule 10b5-1 sales plan adopted by the Reporting Person on March 20, 2026.

F2 · price: The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $33.49 to $34.46. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

SEC source: 0001193125-26-295106 · ownership.xml · nonDerivative · entry 1

Long Daniel D. · CIK 0002040349 · SVP, Drug Discovery

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 99,745

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: 0001193125-26-291059 · ownership.xml · derivative · entry 3

Shaikhly Samira · CIK 0002040363 · Chief People Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 20,865

Underlying: Common Stock · 2,178 shares

Expires 2034-09-22

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: 1/48th of the shares subject to such option vest and become exercisable in substantially equal monthly installments on each monthly anniversary of October 28, 2024, subject to the Reporting Person's continuous service to the Issuer on each such date.

SEC source: 0001193125-26-291059 · ownership.xml · nonDerivative · entry 2

Shaikhly Samira · CIK 0002040363 · Chief People Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 793

F1 · kind: This transaction was effected pursuant to a Rule 10b5-1 sales plan adopted by the Reporting Person on October 31, 2025.

SEC source: 0001193125-26-291059 · ownership.xml · nonDerivative · entry 1

Shaikhly Samira · CIK 0002040363 · Chief People Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 2,971

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: 0001193125-26-291056 · ownership.xml · derivative · entry 1

Bassan Abraham · CIK 0001864485 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 15,000

Underlying: Common Stock · 15,000 shares

Expires 2036-06-25

F1 · derivative.exercise_date: The shares underlying the stock option vest in full upon the earlier of (i) June 26, 2027 or (ii) the date of the Issuer's next annual meeting of stockholders, subject to the Reporting Person's continued service to the Issuer through such vesting date.

SEC source: 0001193125-26-291051 · ownership.xml · derivative · entry 1

Simson Jake · CIK 0001863094 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 15,000

Underlying: Common Stock · 15,000 shares

Expires 2036-06-25

F1 · derivative.exercise_date: The shares underlying the stock option vest in full upon the earlier of (i) June 26, 2027 or (ii) the date of the Issuer's next annual meeting of stockholders, subject to the Reporting Person's continued service to the Issuer through such vesting date.

F2 · ownership.direct: Under the Reporting Person's arrangement with RA Capital Management, L.P. (the "Adviser"), the Reporting Person holds the option for the benefit of the R.A. Capital Healthcare Fund, L.P. (the "Fund") and R.A. Capital Nexus Fund III, L.P. (the "Nexus Fund III"). The Reporting Person is obligated to turn over to the Adviser any net cash or stock received upon exercise of the option, which will offset advisory fees owed by the Fund and the Nexus Fund III to the Adviser. The Reporting Person therefore disclaims beneficial ownership of the option and underlying common stock.

SEC source: 0001193125-26-291054 · ownership.xml · derivative · entry 1

Coulie Bernard · CIK 0001808895 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 15,000

Underlying: Common Stock · 15,000 shares

Expires 2036-06-25

F1 · derivative.exercise_date: The shares underlying the stock option vest in full upon the earlier of (i) June 26, 2027 or (ii) the date of the Issuer's next annual meeting of stockholders, subject to the Reporting Person's continued service to the Issuer through such vesting date.

SEC source: 0001193125-26-291050 · ownership.xml · derivative · entry 1

Ezekowitz Alan · CIK 0001780209 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 15,000

Underlying: Common Stock · 15,000 shares

Expires 2036-06-25

F1 · derivative.exercise_date: The shares underlying the stock option vest in full upon the earlier of (i) June 26, 2027 or (ii) the date of the Issuer's next annual meeting of stockholders, subject to the Reporting Person's continued service to the Issuer through such vesting date.

SEC source: 0001193125-26-291053 · ownership.xml · derivative · entry 1

Tong Jeffrey K · CIK 0001479701 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 15,000

Underlying: Common Stock · 15,000 shares

Expires 2036-06-25

F1 · derivative.exercise_date: The shares underlying the stock option vest in full upon the earlier of (i) June 26, 2027 or (ii) the date of the Issuer's next annual meeting of stockholders, subject to the Reporting Person's continued service to the Issuer through such vesting date.

SEC source: 0001231919-26-000718 · form4-06302026_110616.xml · derivative · entry 1

RA CAPITAL MANAGEMENT, L.P. · CIK 0001346824 · Director · 10% owner

RA Capital Healthcare Fund LP · CIK 0001315082 · Director · 10% owner

RA Capital Nexus Fund III, L.P. · CIK 0001883840 · Director

Kolchinsky Peter · CIK 0001384859 · Director · 10% owner

Shah Rajeev M. · CIK 0001619841 · Director · 10% owner

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

10b5-1 filing: No plan indicated

Ownership: Indirect · See Footnotes

Disclosed balance after: 15,000

Underlying: Common Stock · 15,000 shares

Expires 2036-06-25

F1 · derivative.exercise_date: The shares underlying the stock option vest in full upon the earlier of (i) June 26, 2027 or (ii) the date of the Issuer's next annual meeting of stockholders, subject to Dr. Simson's continued service to the Issuer through such vesting date.

F2 · ownership.nature: RA Capital Management, L.P. (the "Adviser") is the investment manager for RA Capital Healthcare Fund, L.P. (the "Fund") and RA Capital Nexus Fund III, L.P. (the "Nexus Fund III"). The general partner of the Adviser is RA Capital Management GP, LLC (the "Adviser GP"), of which Dr. Peter Kolchinsky and Mr. Rajeev Shah are the managing members. Each of the Adviser, the Adviser GP, the Fund, the Nexus Fund III, Dr. Kolchinsky and Mr. Shah disclaims beneficial ownership of any of the reported securities, except to the extent of its or his respective pecuniary interest therein.

F3 · ownership.nature: Under Dr. Simson's arrangement with the Adviser, Dr. Simson holds the option for the benefit of the Fund and the Nexus Fund III. Dr. Simson is obligated to turn over to the Adviser any net cash or stock received upon exercise of the option, which will offset advisory fees owed by the Fund and the Nexus Fund III to the Adviser. The Reporting Persons therefore disclaim beneficial ownership of the option and underlying common stock.

SEC source: 0001193125-26-291055 · ownership.xml · derivative · entry 1

Sharp Shalini · CIK 0001377202 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 15,000

Underlying: Common Stock · 15,000 shares

Expires 2036-06-25

F1 · derivative.exercise_date: The shares underlying the stock option vest in full upon the earlier of (i) June 26, 2027 or (ii) the date of the Issuer's next annual meeting of stockholders, subject to the Reporting Person's continued service to the Issuer through such vesting date.

SEC source: 0001193125-26-291052 · ownership.xml · derivative · entry 1

Gottesdiener Keith Michael · CIK 0001615856 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 11,260

Underlying: Common Stock · 11,260 shares

Expires 2036-06-25

F1 · derivative.exercise_date: The shares underlying the stock option vest in full upon the earlier of (i) June 26, 2027 or (ii) the date of the Issuer's next annual meeting of stockholders, subject to the Reporting Person's continued service to the Issuer through such vesting date.

SEC source: 0001193125-26-281461 · ownership.xml · derivative · entry 6

Long Daniel D. · CIK 0002040349 · SVP, Drug Discovery

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 25,529

Underlying: Common Stock · 4,471 shares

Expires 2035-08-06

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_date: 1/48th of the shares subject to such option shall vest and become exercisable in substantially equal monthly installments on each monthly anniversary of August 1, 2025, subject to the Reporting Person's continuous service to the Issuer on each such date.

SEC source: 0001193125-26-281461 · ownership.xml · derivative · entry 5

Long Daniel D. · CIK 0002040349 · SVP, Drug Discovery

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 10,376

Underlying: Common Stock · 10,529 shares

Expires 2033-11-11

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_date: 1/48th of the shares subject to such option vest and become exercisable in substantially equal monthly installments on each monthly anniversary of August 1, 2023, subject to the Reporting Person's continuous service to the Issuer on each such date.

SEC source: 0001193125-26-281461 · ownership.xml · nonDerivative · entry 4

Long Daniel D. · CIK 0002040349 · SVP, Drug Discovery

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 96,412

F2 · kind: This transaction was effected pursuant to a Rule 10b5-1 sales plan adopted by the Reporting Person on March 20, 2026.

F4 · price: The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $35.71 to $36.34. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

SEC source: 0001193125-26-281461 · ownership.xml · nonDerivative · entry 3

Long Daniel D. · CIK 0002040349 · SVP, Drug Discovery

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 103,412

F2 · kind: This transaction was effected pursuant to a Rule 10b5-1 sales plan adopted by the Reporting Person on March 20, 2026.

F3 · price: The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $34.70 to $35.64. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

SEC source: 0001193125-26-281461 · ownership.xml · nonDerivative · entry 2

Long Daniel D. · CIK 0002040349 · SVP, Drug Discovery

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 111,412

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: 0001193125-26-281461 · ownership.xml · nonDerivative · entry 1

Long Daniel D. · CIK 0002040349 · SVP, Drug Discovery

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 106,941

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 · balance_after: Includes 3,501 shares acquired under the Septerna, Inc. 2024 Employee Stock Purchase Plan on April 30, 2026 in a transaction that was exempt under Rule 16b-3(c).

SEC source: 0001193125-26-273126 · ownership.xml · derivative · entry 3

Shaikhly Samira · CIK 0002040363 · Chief People Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 23,750

Underlying: Common Stock · 6,250 shares

Expires 2035-08-06

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_date: 1/48th of the shares subject to such option shall vest and become exercisable in substantially equal monthly installments on each monthly anniversary of August 1, 2025, subject to the Reporting Person's continuous service to the Issuer on each such date.

SEC source: 0001193125-26-273126 · ownership.xml · nonDerivative · entry 2

Shaikhly Samira · CIK 0002040363 · Chief People Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 793

F1 · kind: This transaction was effected pursuant to a Rule 10b5-1 sales plan adopted by the Reporting Person on October 31, 2025.

F2 · price: The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $35.00 to $35.19. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

SEC source: 0001193125-26-273126 · ownership.xml · nonDerivative · entry 1

Shaikhly Samira · CIK 0002040363 · Chief People Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 7,043

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: 0001193125-26-255997 · ownership.xml · derivative · entry 9

Shaikhly Samira · CIK 0002040363 · Chief People Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 4,464

Underlying: Common Stock · 637 shares

Expires 2034-03-19

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_date: 1/48th of the shares subject to such option vest and become exercisable in substantially equal monthly installments on each monthly anniversary of March 1, 2024, subject to the Reporting Person's continuous service to the Issuer on each such date.

SEC source: 0001193125-26-255997 · ownership.xml · derivative · entry 8

Shaikhly Samira · CIK 0002040363 · Chief People Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 2,517

Underlying: Common Stock · 943 shares

Expires 2033-11-11

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_date: 25% of the shares underlying this option vested on February 1, 2024, with the remainder vesting in thirty-six substantially equal monthly installments thereafter, subject to the Reporting Person's continuous service the Issuer on each such date.

SEC source: 0001193125-26-255997 · ownership.xml · derivative · entry 7

Shaikhly Samira · CIK 0002040363 · Chief People Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 11,614

Underlying: Common Stock · 4,355 shares

Expires 2033-03-30

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_date: 25% of the shares underlying this option vested on February 1, 2024, with the remainder vesting in thirty-six substantially equal monthly installments thereafter, subject to the Reporting Person's continuous service the Issuer on each such date.

SEC source: 0001193125-26-255997 · ownership.xml · nonDerivative · entry 6

Shaikhly Samira · CIK 0002040363 · Chief People Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 793

F1 · kind: This transaction was effected pursuant to a Rule 10b5-1 sales plan adopted by the Reporting Person on October 31, 2025.

F4 · price: The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $29.29 to $30.08. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.