DYN

SEC source: 0000950170-24-072153 · ownership.xml · nonDerivative · entry 2

HIGH SUSANNA GATTI · CIK 0001691005 · Chief Operating Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 154,062

F1 · kind: The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on March 11, 2024.

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices within the range of $29.85 to $30.61, 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 range(s) set forth in the footnotes of this Form 4.

SEC source: 0000950170-24-072153 · ownership.xml · nonDerivative · entry 1

HIGH SUSANNA GATTI · CIK 0001691005 · Chief Operating Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 234,062

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: 0000950170-24-072140 · ownership.xml · nonDerivative · entry 1

Scalzo Richard William · CIK 0001789545 · SVP, Head of Finance & Admin.

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 115,105

F1 · kind: The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on July 11, 2023.

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices within the range of $30.08 to $30.47, 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 the footnotes of this Form 4.

SEC source: 0000950170-24-064729 · ownership.xml · derivative · entry 1

Stehman-Breen Catherine · CIK 0001702233 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 25,133

Underlying: Common Stock · 25,133 shares

Expires 2034-05-21

F1 · derivative.exercise_date: This option was granted on May 22, 2024. The shares underlying the option are scheduled to vest in full on the earlier of (i) May 22, 2025 or (ii) the date of the Issuer's 2025 Annual Meeting of Stockholders, subject to continued service.

SEC source: 0000950170-24-064727 · ownership.xml · derivative · entry 1

Incerti Carlo · CIK 0001915358 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 25,133

Underlying: Common Stock · 25,133 shares

Expires 2034-05-21

F1 · derivative.exercise_date: This option was granted on May 22, 2024. The shares underlying the option are scheduled to vest in full on the earlier of (i) May 22, 2025 or (ii) the date of the Issuer's 2025 Annual Meeting of Stockholders, subject to continued service.

SEC source: 0000950170-24-064728 · ownership.xml · derivative · entry 1

Kersten Dirk · CIK 0001823682 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 25,133

Underlying: Common Stock · 25,133 shares

Expires 2034-05-21

F1 · derivative.exercise_date: This option was granted on May 22, 2024. The shares underlying the option are scheduled to vest in full on the earlier of (i) May 22, 2025 or (ii) the date of the Issuer's 2025 Annual Meeting of Stockholders, subject to continued service.

SEC source: 0000950170-24-064726 · ownership.xml · derivative · entry 1

HURWITZ EDWARD · CIK 0001211840 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 25,133

Underlying: Common Stock · 25,133 shares

Expires 2034-05-21

F1 · derivative.exercise_date: This option was granted on May 22, 2024. The shares underlying the option are scheduled to vest in full on the earlier of (i) May 22, 2025 or (ii) the date of the Issuer's 2025 Annual Meeting of Stockholders, subject to continued service.

SEC source: 0000950170-24-064725 · ownership.xml · derivative · entry 1

Rhodes Jason P · CIK 0001577014 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 25,133

Underlying: Common Stock · 25,133 shares

Expires 2034-05-21

F1 · derivative.exercise_date: This option was granted on May 22, 2024. The shares underlying the option are scheduled to vest in full on the earlier of (i) May 22, 2025 or (ii) the date of the Issuer's 2025 Annual Meeting of Stockholders, subject to continued service.

F2 · ownership.direct: The Reporting Person is a member of Atlas Venture Associates XI, LLC and is obligated to transfer the economic benefit, if any, received upon the sale of the shares issuable upon exercise of the option to Atlas Venture Life Science Advisors, LLC. As such, the Reporting Person disclaims beneficial ownership of the securities reported herein for purposes of Section 16 of the Securities Exchange Act of 1934, as amended, except to the extent of his pecuniary interest therein, if any.

SEC source: 0000950170-24-064724 · ownership.xml · derivative · entry 1

Lubner David Charles · CIK 0001572000 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 25,133

Underlying: Common Stock · 25,133 shares

Expires 2034-05-21

F1 · derivative.exercise_date: This option was granted on May 22, 2024. The shares underlying the option are scheduled to vest in full on the earlier of (i) May 22, 2025 or (ii) the date of the Issuer's 2025 Annual Meeting of Stockholders, subject to continued service.

SEC source: 0000950170-24-063737 · ownership.xml · derivative · entry 5

Beskrovnaya Oxana · CIK 0001824542 · Chief Scientific Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 30,426 shares

Expires 2030-01-05

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: The option was granted on January 6, 2020. The shares underlying the option vest over four years, with 25% of the shares vesting on January 27, 2021 and the remaining shares vesting in equal quarterly installments thereafter.

SEC source: 0000950170-24-063737 · ownership.xml · nonDerivative · entry 4

Beskrovnaya Oxana · CIK 0001824542 · Chief Scientific Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 149,647

F1 · kind: The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on June 30, 2023.

F4 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices within the range of $34.02 to $34.16, inclusive.

F5 · balance_after: Includes 130,308 unvested RSUs.

SEC source: 0000950170-24-063737 · ownership.xml · nonDerivative · entry 3

Beskrovnaya Oxana · CIK 0001824542 · Chief Scientific Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 150,792

F1 · kind: The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on June 30, 2023.

F3 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices within the range of $33.01 to $34.01, inclusive.

SEC source: 0000950170-24-063737 · ownership.xml · nonDerivative · entry 2

Beskrovnaya Oxana · CIK 0001824542 · Chief Scientific Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 162,939

F1 · kind: The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on June 30, 2023.

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices within the range of $32.00 to $33.00, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in the footnotes of this Form 4.

SEC source: 0000950170-24-063737 · ownership.xml · nonDerivative · entry 1

Beskrovnaya Oxana · CIK 0001824542 · Chief Scientific Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 180,073

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: 0000950170-24-062080 · ownership.xml · nonDerivative · entry 2

Beskrovnaya Oxana · CIK 0001824542 · Chief Scientific Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 149,647

F1 · shares: Represents shares automatically sold by the Reporting Person to satisfy tax withholding obligations in connection with the vesting of restricted stock units granted to the Reporting Person on November 15, 2023. The automatic sale of the Reporting Person's shares is provided for in a restricted stock unit agreement constituting a "binding contract" consistent with the affirmative defense to liability under Rule 10b5-1 that was entered into on January 25, 2024 and the sale does not represent a discretionary trade by the Reporting Person.

F3 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices within the range of $28.51 to $28.70, inclusive.

F4 · balance_after: Includes 130,308 unvested RSUs.

SEC source: 0000950170-24-062080 · ownership.xml · nonDerivative · entry 1

Beskrovnaya Oxana · CIK 0001824542 · Chief Scientific Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 150,130

F1 · shares: Represents shares automatically sold by the Reporting Person to satisfy tax withholding obligations in connection with the vesting of restricted stock units granted to the Reporting Person on November 15, 2023. The automatic sale of the Reporting Person's shares is provided for in a restricted stock unit agreement constituting a "binding contract" consistent with the affirmative defense to liability under Rule 10b5-1 that was entered into on January 25, 2024 and the sale does not represent a discretionary trade by the Reporting Person.

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices within the range of $27.50 to $28.50, 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 the footnotes of this Form 4.

SEC source: 0000950170-24-062079 · ownership.xml · nonDerivative · entry 2

Farwell Wildon · CIK 0001847941 · Chief Medical Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 148,179

F1 · shares: Represents shares automatically sold by the Reporting Person to satisfy tax withholding obligations in connection with the vesting of restricted stock units granted to the Reporting Person on November 15, 2023. The automatic sale of the Reporting Person's shares is provided for in a restricted stock unit agreement constituting a "binding contract" consistent with the affirmative defense to liability under Rule 10b5-1 that was entered into on January 25, 2024 and the sale does not represent a discretionary trade by the Reporting Person.

F3 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices within the range of $28.51 to $28.70, inclusive.

F4 · balance_after: Includes 119,209 unvested RSUs.

SEC source: 0000950170-24-062079 · ownership.xml · nonDerivative · entry 1

Farwell Wildon · CIK 0001847941 · Chief Medical Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 148,604

F1 · shares: Represents shares automatically sold by the Reporting Person to satisfy tax withholding obligations in connection with the vesting of restricted stock units granted to the Reporting Person on November 15, 2023. The automatic sale of the Reporting Person's shares is provided for in a restricted stock unit agreement constituting a "binding contract" consistent with the affirmative defense to liability under Rule 10b5-1 that was entered into on January 25, 2024 and the sale does not represent a discretionary trade by the Reporting Person.

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices within the range of $27.50 to $28.50, 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 the footnotes of this Form 4.

SEC source: 0000950170-24-062078 · ownership.xml · nonDerivative · entry 2

HIGH SUSANNA GATTI · CIK 0001691005 · Chief Operating Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 154,062

F1 · shares: Represents shares automatically sold by the Reporting Person to satisfy tax withholding obligations in connection with the vesting of restricted stock units granted to the Reporting Person on November 15, 2023. The automatic sale of the Reporting Person's shares is provided for in a restricted stock unit agreement constituting a "binding contract" consistent with the affirmative defense to liability under Rule 10b5-1 that was entered into on January 25, 2024 and the sale does not represent a discretionary trade by the Reporting Person.

F3 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices within the range of $28.51 to $28.70, inclusive.

F4 · balance_after: Includes 139,899 unvested RSUs.

SEC source: 0000950170-24-062078 · ownership.xml · nonDerivative · entry 1

HIGH SUSANNA GATTI · CIK 0001691005 · Chief Operating Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 154,551

F1 · shares: Represents shares automatically sold by the Reporting Person to satisfy tax withholding obligations in connection with the vesting of restricted stock units granted to the Reporting Person on November 15, 2023. The automatic sale of the Reporting Person's shares is provided for in a restricted stock unit agreement constituting a "binding contract" consistent with the affirmative defense to liability under Rule 10b5-1 that was entered into on January 25, 2024 and the sale does not represent a discretionary trade by the Reporting Person.

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices within the range of $27.50 to $28.50, 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 the footnotes of this Form 4.

SEC source: 0000950170-24-062077 · ownership.xml · nonDerivative · entry 2

Scalzo Richard William · CIK 0001789545 · SVP, Head of Finance & Admin.

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 116,695

F1 · shares: Represents shares automatically sold by the Reporting Person to satisfy tax withholding obligations in connection with the vesting of restricted stock units granted to the Reporting Person on November 15, 2023. The automatic sale of the Reporting Person's shares is provided for in a restricted stock unit agreement constituting a "binding contract" consistent with the affirmative defense to liability under Rule 10b5-1 that was entered into on January 25, 2024 and the sale does not represent a discretionary trade by the Reporting Person.

F3 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices within the range of $28.51 to $28.70, inclusive.

F4 · balance_after: Includes 110,016 unvested RSUs.

SEC source: 0000950170-24-062077 · ownership.xml · nonDerivative · entry 1

Scalzo Richard William · CIK 0001789545 · SVP, Head of Finance & Admin.

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 117,157

F1 · shares: Represents shares automatically sold by the Reporting Person to satisfy tax withholding obligations in connection with the vesting of restricted stock units granted to the Reporting Person on November 15, 2023. The automatic sale of the Reporting Person's shares is provided for in a restricted stock unit agreement constituting a "binding contract" consistent with the affirmative defense to liability under Rule 10b5-1 that was entered into on January 25, 2024 and the sale does not represent a discretionary trade by the Reporting Person.

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices within the range of $27.50 to $28.50, 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 the footnotes of this Form 4.

SEC source: 0000950170-24-062075 · ownership.xml · nonDerivative · entry 2

McNeill Jonathan · CIK 0001824673 · Chief Business Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 136,634

F1 · shares: Represents shares automatically sold by the Reporting Person to satisfy tax withholding obligations in connection with the vesting of restricted stock units granted to the Reporting Person on November 15, 2023. The automatic sale of the Reporting Person's shares is provided for in a restricted stock unit agreement constituting a "binding contract" consistent with the affirmative defense to liability under Rule 10b5-1 that was entered into on January 25, 2024 and the sale does not represent a discretionary trade by the Reporting Person.

F3 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices within the range of $28.51 to $28.70, inclusive.

F4 · balance_after: Includes 126,967 unvested RSUs.

SEC source: 0000950170-24-062075 · ownership.xml · nonDerivative · entry 1

McNeill Jonathan · CIK 0001824673 · Chief Business Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 137,129

F1 · shares: Represents shares automatically sold by the Reporting Person to satisfy tax withholding obligations in connection with the vesting of restricted stock units granted to the Reporting Person on November 15, 2023. The automatic sale of the Reporting Person's shares is provided for in a restricted stock unit agreement constituting a "binding contract" consistent with the affirmative defense to liability under Rule 10b5-1 that was entered into on January 25, 2024 and the sale does not represent a discretionary trade by the Reporting Person.

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices within the range of $27.50 to $28.50, 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 the footnotes of this Form 4.

SEC source: 0000950170-24-037226 · ownership.xml · derivative · entry 1

Cox John · CIK 0001498428 · Director · See Remarks

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 679,853

Underlying: Common Stock · 679,853 shares

Expires 2034-03-24

F1 · derivative.exercise_date: This option was granted on March 25, 2024. The shares underlying the option are scheduled to vest over four years, with 25% of the shares vesting on March 25, 2025, and the remainder vesting in equal monthly installments thereafter, subject to continuous service

SEC source: 0000950170-24-030483 · ownership.xml · nonDerivative · entry 2

Farwell Wildon · CIK 0001847941 · Chief Medical Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 150,560

F4 · shares: The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on July 14, 2023.

F5 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices within the range of $25.55 to $25.63, inclusive.

F3 · balance_after: Includes 124,366 unvested RSUs.

SEC source: 0000950170-24-030443 · ownership.xml · nonDerivative · entry 1

Beskrovnaya Oxana · CIK 0001824542 · Chief Scientific Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 152,352

F1 · shares: Represents shares automatically sold by the Reporting Person to satisfy tax withholding obligations in connection with the vesting of restricted stock units granted to the Reporting Person on December 10, 2021 and December 9, 2022. The automatic sale of the Reporting Person's shares is provided for in a restricted stock unit agreement constituting a "binding contract" consistent with the affirmative defense to liability under Rule 10b5-1 and the sale does not represent a discretionary trade by the Reporting Person.

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices within the range of $25.50 to $26.09, 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 of this Form 4.

F3 · balance_after: Includes 136,165 unvested RSUs.

SEC source: 0000950170-24-030483 · ownership.xml · nonDerivative · entry 1

Farwell Wildon · CIK 0001847941 · Chief Medical Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 151,590

F1 · shares: Represents shares automatically sold by the Reporting Person to satisfy tax withholding obligations in connection with the vesting of restricted stock units granted to the Reporting Person on December 10, 2021 and December 9, 2022. The automatic sale of the Reporting Person's shares is provided for in a restricted stock unit agreement constituting a "binding contract" consistent with the affirmative defense to liability under Rule 10b5-1 and the sale does not represent a discretionary trade by the Reporting Person.

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices within the range of $25.50 to $26.09, 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 of this Form 4.

F3 · balance_after: Includes 124,366 unvested RSUs.

SEC source: 0000950170-24-030482 · ownership.xml · nonDerivative · entry 7

Scalzo Richard William · CIK 0001789545 · SVP, Head of Finance & Admin.

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 119,283

F6 · shares: The sale reported in this Form 4 was effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on July 11, 2023.

F7 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices within the range of $24.83 to $25.23, inclusive.

F8 · balance_after: Includes 115,624 unvested RSUs.

SEC source: 0000950170-24-030482 · ownership.xml · nonDerivative · entry 6

Scalzo Richard William · CIK 0001789545 · SVP, Head of Finance & Admin.

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 120,873

F4 · shares: Represents shares automatically sold by the Reporting Person to satisfy tax withholding obligations in connection with the vesting of restricted stock units granted to the Reporting Person on December 10, 2021 and December 9, 2022. The automatic sale of the Reporting Person's shares is provided for in a restricted stock unit agreement constituting a "binding contract" consistent with the affirmative defense to liability under Rule 10b5-1 and the sale does not represent a discretionary trade by the Reporting Person.

F5 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices within the range of $25.50 to $26.09, inclusive.

SEC source: 0000950170-24-030479 · ownership.xml · derivative · entry 13

Brumm Joshua T · CIK 0001528826 · Director · CEO & President

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 83,269

Underlying: Common Stock · 50,000 shares

Expires 2030-07-30

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.

F11 · derivative.exercise_date: The option was granted on July 31, 2020. The shares underlying the option vest over four years in sixteen equal installments beginning on October 31, 2020.

SEC source: 0000950170-24-030479 · ownership.xml · nonDerivative · entry 10

Brumm Joshua T · CIK 0001528826 · Director · CEO & President

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 537,998

F8 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices within the range of $25.68 to $26.05, inclusive.

F9 · balance_after: Includes 513,913 unvested RSUs.

SEC source: 0000950170-24-030479 · ownership.xml · nonDerivative · entry 9

Brumm Joshua T · CIK 0001528826 · Director · CEO & President

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 546,616

F6 · shares: Represents shares automatically sold by the Reporting Person to satisfy tax withholding obligations in connection with the vesting of restricted stock units granted to the Reporting Person on December 10, 2021 and December 9, 2022. The automatic sale of the Reporting Person's shares is provided for in a restricted stock unit agreement constituting a "binding contract" consistent with the affirmative defense to liability under Rule 10b5-1 and the sale does not represent a discretionary trade by the Reporting Person.

F7 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices within the range of $25.22 to $26.18, inclusive.

SEC source: 0000950170-24-030479 · ownership.xml · nonDerivative · entry 8

Brumm Joshua T · CIK 0001528826 · Director · CEO & President

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 554,385

F5 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices within the range of $26.01 to $26.10, inclusive.

SEC source: 0000950170-24-030479 · ownership.xml · nonDerivative · entry 7

Brumm Joshua T · CIK 0001528826 · Director · CEO & President

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 564,313

F4 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices within the range of $25.00 to $25.75, inclusive.

SEC source: 0000950170-24-030479 · ownership.xml · nonDerivative · entry 6

Brumm Joshua T · CIK 0001528826 · Director · CEO & President

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 604,385

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: 0000950170-24-030485 · ownership.xml · nonDerivative · entry 3

HIGH SUSANNA GATTI · CIK 0001691005 · Chief Operating Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 156,800

F3 · shares: Represents shares automatically sold by the Reporting Person to satisfy tax withholding obligations in connection with the vesting of restricted stock units granted to the Reporting Person on December 10, 2021 and December 9, 2022. The automatic sale of the Reporting Person's shares is provided for in a restricted stock unit agreement constituting a "binding contract" consistent with the affirmative defense to liability under Rule 10b5-1 and the sale does not represent a discretionary trade by the Reporting Person.

F4 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices within the range of $25.50 to $26.09, inclusive.

F5 · balance_after: Includes 145,829 unvested RSUs.

SEC source: 0000950170-24-030484 · ownership.xml · derivative · entry 11

McNeill Jonathan · CIK 0001824673 · Chief Business Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 17,825 shares

Expires 2030-07-30

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.

F9 · derivative.exercise_date: The option was granted on July 31, 2020, with 100% of the option to vest upon the clearance date of an IND application submitted to the FDA by the Company with respect to one ofitsproduct candidates. On July 5, 2022, in connection with the clearance by the FDA of the Company's IND application for DYNE-251, the Compensation Committee determined thattheperformance condition had been achieved.

SEC source: 0000950170-24-030484 · ownership.xml · nonDerivative · entry 8

McNeill Jonathan · CIK 0001824673 · Chief Business Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 139,408

F5 · shares: Represents shares automatically sold by the Reporting Person to satisfy tax withholding obligations in connection with the vesting of restricted stock units granted to the Reporting Person on December 10, 2021 and December 9, 2022. The automatic sale of the Reporting Person's shares is provided for in a restricted stock unit agreement constituting a "binding contract" consistent with the affirmative defense to liability under Rule 10b5-1 and the sale does not represent a discretionary trade by the Reporting Person.

F6 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices within the range of $25.67 to $25.81, inclusive.

F7 · balance_after: Includes 132,976 unvested RSUs.

SEC source: 0000950170-24-030484 · ownership.xml · nonDerivative · entry 7

McNeill Jonathan · CIK 0001824673 · Chief Business Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 141,184

F4 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices within the range of $25.14 to $26.09, inclusive.

SEC source: 0000950170-24-030484 · ownership.xml · nonDerivative · entry 6

McNeill Jonathan · CIK 0001824673 · Chief Business Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 159,009

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: 0000950170-24-030482 · ownership.xml · derivative · entry 9

Scalzo Richard William · CIK 0001789545 · SVP, Head of Finance & Admin.

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 17,333 shares

Expires 2030-07-30

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.

F10 · derivative.exercise_date: The option was granted on July 31, 2020, with 100% of the option to vest upon the clearance date of an IND application submitted to the FDA by the Company with respect to one of its product candidates. On July 5, 2022, in connection with the clearance by the FDA of the Company's IND application for DYNE-251, the Compensation Committee determined that the performance condition had been achieved.

SEC source: 0000950170-24-030482 · ownership.xml · derivative · entry 8

Scalzo Richard William · CIK 0001789545 · SVP, Head of Finance & Admin.

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 9,855

Underlying: Common Stock · 68,919 shares

Expires 2030-07-30

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.

F9 · derivative.exercise_date: The option was granted on July 31, 2020. The shares underlying the option vest over four years in equal quarterly installments through July 31, 2024 provided that no shares shall vest prior to December 2, 2020.

SEC source: 0000950170-24-030482 · ownership.xml · nonDerivative · entry 5

Scalzo Richard William · CIK 0001789545 · SVP, Head of Finance & Admin.

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 121,955

F3 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices within the range of $27.27 to $27.39, inclusive.

SEC source: 0000950170-24-030482 · ownership.xml · nonDerivative · entry 4

Scalzo Richard William · CIK 0001789545 · SVP, Head of Finance & Admin.

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 122,244

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices within the range of $26.20 to $27.15, inclusive.

SEC source: 0000950170-24-030482 · ownership.xml · nonDerivative · entry 3

Scalzo Richard William · CIK 0001789545 · SVP, Head of Finance & Admin.

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 177,452

F1 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices within the range of $25.20 to $26.19, 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 Form 4.

SEC source: 0000950170-24-030482 · ownership.xml · nonDerivative · entry 2

Scalzo Richard William · CIK 0001789545 · SVP, Head of Finance & Admin.

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 208,207

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: 0000950170-24-030482 · ownership.xml · nonDerivative · entry 1

Scalzo Richard William · CIK 0001789545 · SVP, Head of Finance & Admin.

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 190,874

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: 0000950170-24-030479 · ownership.xml · derivative · entry 12

Brumm Joshua T · CIK 0001528826 · Director · CEO & President

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 133,269

Underlying: Common Stock · 209,412 shares

Expires 2030-07-30

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.

F11 · derivative.exercise_date: The option was granted on July 31, 2020. The shares underlying the option vest over four years in sixteen equal installments beginning on October 31, 2020.

SEC source: 0000950170-24-030479 · ownership.xml · derivative · entry 11

Brumm Joshua T · CIK 0001528826 · Director · CEO & President

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 153,931 shares

Expires 2030-07-30

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.

F10 · derivative.exercise_date: The option was granted on July 31, 2020, with 100% of the option to vest upon the clearance date of an IND application submitted to the FDA by the Company with respect to one of its product candidates. On July 5, 2022, in connection with the clearance by the FDA of the Company's IND application for DYNE-251, the Compensation Committee determined that the performance condition had been achieved.