McArthur James G

SEC source: 0001835597-26-000012 · form4.xml · nonDerivative · entry 2

McArthur James G · CIK 0001763307 · Director · President and CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 296,326

F1 · kind: Represents shares automatically sold by the Company on behalf of the Reporting Person pursuant to a mandatory sell-to-cover provision in the award agreement required to cover minimum statutory tax withholding obligations that became due upon the vesting and settlement of restricted stock units ("RSUs"). The mandatory sale of the Reporting Person's shares was provided for in a RSU 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.

SEC source: 0001835597-26-000012 · form4.xml · nonDerivative · entry 1

McArthur James G · CIK 0001763307 · Director · President and CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 296,457

F1 · kind: Represents shares automatically sold by the Company on behalf of the Reporting Person pursuant to a mandatory sell-to-cover provision in the award agreement required to cover minimum statutory tax withholding obligations that became due upon the vesting and settlement of restricted stock units ("RSUs"). The mandatory sale of the Reporting Person's shares was provided for in a RSU 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.

SEC source: 0001835597-26-000002 · form4.xml · derivative · entry 2

McArthur James G · CIK 0001763307 · Director · President and CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 731,250

Underlying: Common Stock · 731,250 shares

Expires 2036-02-29

F2 · derivative.exercise_date: This option shall vest and become exercisable as follows: 25% of the shares on the one-year anniversary of the Grant Date, with the remaining 75% vesting and becoming exercisable in 36 equal monthly installments thereafter, subject to the Reporting Person's continued service to the Issuer on each such vesting date.

SEC source: 0001835597-26-000002 · form4.xml · nonDerivative · entry 1

McArthur James G · CIK 0001763307 · Director · President and CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 301,601

F1 · shares: Consists of 187,688 restricted stock units ("RSUs"), each representing the contingent right to receive one share of Common Stock upon vesting. The RSUs vest in equal annual installments over four years, with the first installment vesting on March 1, 2027, subject to the Reporting Person's continued service to the Issuer on each such vesting date.

SEC source: 0001835597-25-000015 · form4.xml · derivative · entry 14

McArthur James G · CIK 0001763307 · Director · President and CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 300,000

Underlying: Common Stock · 300,000 shares

Expires 2034-02-28

F1 · kind: On November 4, 2025, the Issuer's Board of Directors approved a repricing of the Reporting Person's outstanding stock options granted under the Issuer's 2020 Stock Plan, 2022 Stock Option and Incentive Plan, and 2024 Inducement Plan. The exercise price of eligible options was reduced to $4.53, with all other terms unchanged except that the reduced exercise price is available only if the Reporting Person satisfies the applicable retention period; otherwise, the original exercise price will apply. The transactions reported herein are exempt pursuant to Rules 16b-6(d) and 16b-3 under the Securities Exchange Act of 1934.

F6 · derivative.exercise_date: This option shall vest as follows: twenty-five percent (25%) on the one-year anniversary of the Grant Date and the remainder vesting in thirty-six (36) equal monthly installments, subject to the option recipient's continued service or employment with the Company on each applicable vesting date.

SEC source: 0001835597-25-000015 · form4.xml · derivative · entry 13

McArthur James G · CIK 0001763307 · Director · President and CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 300,000 shares

Expires 2034-02-28

F1 · kind: On November 4, 2025, the Issuer's Board of Directors approved a repricing of the Reporting Person's outstanding stock options granted under the Issuer's 2020 Stock Plan, 2022 Stock Option and Incentive Plan, and 2024 Inducement Plan. The exercise price of eligible options was reduced to $4.53, with all other terms unchanged except that the reduced exercise price is available only if the Reporting Person satisfies the applicable retention period; otherwise, the original exercise price will apply. The transactions reported herein are exempt pursuant to Rules 16b-6(d) and 16b-3 under the Securities Exchange Act of 1934.

F6 · derivative.exercise_date: This option shall vest as follows: twenty-five percent (25%) on the one-year anniversary of the Grant Date and the remainder vesting in thirty-six (36) equal monthly installments, subject to the option recipient's continued service or employment with the Company on each applicable vesting date.

SEC source: 0001835597-25-000015 · form4.xml · derivative · entry 12

McArthur James G · CIK 0001763307 · Director · President and CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 275,000

Underlying: Common Stock · 275,000 shares

Expires 2033-02-28

F1 · kind: On November 4, 2025, the Issuer's Board of Directors approved a repricing of the Reporting Person's outstanding stock options granted under the Issuer's 2020 Stock Plan, 2022 Stock Option and Incentive Plan, and 2024 Inducement Plan. The exercise price of eligible options was reduced to $4.53, with all other terms unchanged except that the reduced exercise price is available only if the Reporting Person satisfies the applicable retention period; otherwise, the original exercise price will apply. The transactions reported herein are exempt pursuant to Rules 16b-6(d) and 16b-3 under the Securities Exchange Act of 1934.

F6 · derivative.exercise_date: This option shall vest as follows: twenty-five percent (25%) on the one-year anniversary of the Grant Date and the remainder vesting in thirty-six (36) equal monthly installments, subject to the option recipient's continued service or employment with the Company on each applicable vesting date.

SEC source: 0001835597-25-000015 · form4.xml · derivative · entry 11

McArthur James G · CIK 0001763307 · Director · President and CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 275,000 shares

Expires 2033-02-28

F1 · kind: On November 4, 2025, the Issuer's Board of Directors approved a repricing of the Reporting Person's outstanding stock options granted under the Issuer's 2020 Stock Plan, 2022 Stock Option and Incentive Plan, and 2024 Inducement Plan. The exercise price of eligible options was reduced to $4.53, with all other terms unchanged except that the reduced exercise price is available only if the Reporting Person satisfies the applicable retention period; otherwise, the original exercise price will apply. The transactions reported herein are exempt pursuant to Rules 16b-6(d) and 16b-3 under the Securities Exchange Act of 1934.

F6 · derivative.exercise_date: This option shall vest as follows: twenty-five percent (25%) on the one-year anniversary of the Grant Date and the remainder vesting in thirty-six (36) equal monthly installments, subject to the option recipient's continued service or employment with the Company on each applicable vesting date.

SEC source: 0001835597-25-000015 · form4.xml · derivative · entry 10

McArthur James G · CIK 0001763307 · Director · President and CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 466,095

Underlying: Common Stock · 466,095 shares

Expires 2032-05-05

F1 · kind: On November 4, 2025, the Issuer's Board of Directors approved a repricing of the Reporting Person's outstanding stock options granted under the Issuer's 2020 Stock Plan, 2022 Stock Option and Incentive Plan, and 2024 Inducement Plan. The exercise price of eligible options was reduced to $4.53, with all other terms unchanged except that the reduced exercise price is available only if the Reporting Person satisfies the applicable retention period; otherwise, the original exercise price will apply. The transactions reported herein are exempt pursuant to Rules 16b-6(d) and 16b-3 under the Securities Exchange Act of 1934.

F6 · derivative.exercise_date: This option shall vest as follows: twenty-five percent (25%) on the one-year anniversary of the Grant Date and the remainder vesting in thirty-six (36) equal monthly installments, subject to the option recipient's continued service or employment with the Company on each applicable vesting date.

SEC source: 0001835597-25-000015 · form4.xml · derivative · entry 9

McArthur James G · CIK 0001763307 · Director · President and CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 466,095 shares

Expires 2032-05-05

F1 · kind: On November 4, 2025, the Issuer's Board of Directors approved a repricing of the Reporting Person's outstanding stock options granted under the Issuer's 2020 Stock Plan, 2022 Stock Option and Incentive Plan, and 2024 Inducement Plan. The exercise price of eligible options was reduced to $4.53, with all other terms unchanged except that the reduced exercise price is available only if the Reporting Person satisfies the applicable retention period; otherwise, the original exercise price will apply. The transactions reported herein are exempt pursuant to Rules 16b-6(d) and 16b-3 under the Securities Exchange Act of 1934.

F6 · derivative.exercise_date: This option shall vest as follows: twenty-five percent (25%) on the one-year anniversary of the Grant Date and the remainder vesting in thirty-six (36) equal monthly installments, subject to the option recipient's continued service or employment with the Company on each applicable vesting date.

SEC source: 0001835597-25-000015 · form4.xml · derivative · entry 8

McArthur James G · CIK 0001763307 · Director · President and CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 40,815

Underlying: Common Stock · 40,815 shares

Expires 2032-03-06

F1 · kind: On November 4, 2025, the Issuer's Board of Directors approved a repricing of the Reporting Person's outstanding stock options granted under the Issuer's 2020 Stock Plan, 2022 Stock Option and Incentive Plan, and 2024 Inducement Plan. The exercise price of eligible options was reduced to $4.53, with all other terms unchanged except that the reduced exercise price is available only if the Reporting Person satisfies the applicable retention period; otherwise, the original exercise price will apply. The transactions reported herein are exempt pursuant to Rules 16b-6(d) and 16b-3 under the Securities Exchange Act of 1934.

F5 · derivative.exercise_date: This stock option vests over four years following the vesting commencement date (March 7, 2022) with 25% of such shares vesting on the first anniversary of the vesting commencement date, and the remaining shares vesting in 36 equal monthly installments, subject to continued service through each vesting date.

SEC source: 0001835597-25-000015 · form4.xml · derivative · entry 7

McArthur James G · CIK 0001763307 · Director · President and CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 40,815 shares

Expires 2032-03-06

F1 · kind: On November 4, 2025, the Issuer's Board of Directors approved a repricing of the Reporting Person's outstanding stock options granted under the Issuer's 2020 Stock Plan, 2022 Stock Option and Incentive Plan, and 2024 Inducement Plan. The exercise price of eligible options was reduced to $4.53, with all other terms unchanged except that the reduced exercise price is available only if the Reporting Person satisfies the applicable retention period; otherwise, the original exercise price will apply. The transactions reported herein are exempt pursuant to Rules 16b-6(d) and 16b-3 under the Securities Exchange Act of 1934.

F5 · derivative.exercise_date: This stock option vests over four years following the vesting commencement date (March 7, 2022) with 25% of such shares vesting on the first anniversary of the vesting commencement date, and the remaining shares vesting in 36 equal monthly installments, subject to continued service through each vesting date.

SEC source: 0001835597-25-000015 · form4.xml · derivative · entry 6

McArthur James G · CIK 0001763307 · Director · President and CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 40,815

Underlying: Common Stock · 40,815 shares

Expires 2031-09-05

F1 · kind: On November 4, 2025, the Issuer's Board of Directors approved a repricing of the Reporting Person's outstanding stock options granted under the Issuer's 2020 Stock Plan, 2022 Stock Option and Incentive Plan, and 2024 Inducement Plan. The exercise price of eligible options was reduced to $4.53, with all other terms unchanged except that the reduced exercise price is available only if the Reporting Person satisfies the applicable retention period; otherwise, the original exercise price will apply. The transactions reported herein are exempt pursuant to Rules 16b-6(d) and 16b-3 under the Securities Exchange Act of 1934.

F4 · derivative.exercise_date: This stock option vests over four years following the vesting commencement date (October 6, 2021) with 25% of such shares vesting on the first anniversary of the vesting commencement date, and the remaining shares vesting in 36 equal monthly installments, subject to continued service through each vesting date.

SEC source: 0001835597-25-000015 · form4.xml · derivative · entry 5

McArthur James G · CIK 0001763307 · Director · President and CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 40,815 shares

Expires 2031-09-05

F1 · kind: On November 4, 2025, the Issuer's Board of Directors approved a repricing of the Reporting Person's outstanding stock options granted under the Issuer's 2020 Stock Plan, 2022 Stock Option and Incentive Plan, and 2024 Inducement Plan. The exercise price of eligible options was reduced to $4.53, with all other terms unchanged except that the reduced exercise price is available only if the Reporting Person satisfies the applicable retention period; otherwise, the original exercise price will apply. The transactions reported herein are exempt pursuant to Rules 16b-6(d) and 16b-3 under the Securities Exchange Act of 1934.

F4 · derivative.exercise_date: This stock option vests over four years following the vesting commencement date (October 6, 2021) with 25% of such shares vesting on the first anniversary of the vesting commencement date, and the remaining shares vesting in 36 equal monthly installments, subject to continued service through each vesting date.

SEC source: 0001835597-25-000015 · form4.xml · derivative · entry 4

McArthur James G · CIK 0001763307 · Director · President and CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 40,815

Underlying: Common Stock · 40,815 shares

Expires 2031-09-05

F1 · kind: On November 4, 2025, the Issuer's Board of Directors approved a repricing of the Reporting Person's outstanding stock options granted under the Issuer's 2020 Stock Plan, 2022 Stock Option and Incentive Plan, and 2024 Inducement Plan. The exercise price of eligible options was reduced to $4.53, with all other terms unchanged except that the reduced exercise price is available only if the Reporting Person satisfies the applicable retention period; otherwise, the original exercise price will apply. The transactions reported herein are exempt pursuant to Rules 16b-6(d) and 16b-3 under the Securities Exchange Act of 1934.

F3 · derivative.exercise_date: This stock option vests over four years following the vesting commencement date (September 17, 2021) with 25% of such shares vesting on the first anniversary of the vesting commencement date, and the remaining shares vesting in 36 equal monthly installments, subject to continued service through each vesting date.

SEC source: 0001835597-25-000015 · form4.xml · derivative · entry 3

McArthur James G · CIK 0001763307 · Director · President and CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 40,815 shares

Expires 2031-09-05

F1 · kind: On November 4, 2025, the Issuer's Board of Directors approved a repricing of the Reporting Person's outstanding stock options granted under the Issuer's 2020 Stock Plan, 2022 Stock Option and Incentive Plan, and 2024 Inducement Plan. The exercise price of eligible options was reduced to $4.53, with all other terms unchanged except that the reduced exercise price is available only if the Reporting Person satisfies the applicable retention period; otherwise, the original exercise price will apply. The transactions reported herein are exempt pursuant to Rules 16b-6(d) and 16b-3 under the Securities Exchange Act of 1934.

F3 · derivative.exercise_date: This stock option vests over four years following the vesting commencement date (September 17, 2021) with 25% of such shares vesting on the first anniversary of the vesting commencement date, and the remaining shares vesting in 36 equal monthly installments, subject to continued service through each vesting date.

SEC source: 0001835597-25-000015 · form4.xml · derivative · entry 2

McArthur James G · CIK 0001763307 · Director · President and CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 352,705

Underlying: Common Stock · 352,705 shares

Expires 2031-09-05

F1 · kind: On November 4, 2025, the Issuer's Board of Directors approved a repricing of the Reporting Person's outstanding stock options granted under the Issuer's 2020 Stock Plan, 2022 Stock Option and Incentive Plan, and 2024 Inducement Plan. The exercise price of eligible options was reduced to $4.53, with all other terms unchanged except that the reduced exercise price is available only if the Reporting Person satisfies the applicable retention period; otherwise, the original exercise price will apply. The transactions reported herein are exempt pursuant to Rules 16b-6(d) and 16b-3 under the Securities Exchange Act of 1934.

F2 · derivative.exercise_date: This stock option vests over four years following the vesting commencement date (September 6, 2021) with 25% of such shares vesting on the first anniversary of the vesting commencement date, and the remaining shares vesting in 36 equal monthly installments, subject to continued service through each vesting date.

SEC source: 0001835597-25-000015 · form4.xml · derivative · entry 1

McArthur James G · CIK 0001763307 · Director · President and CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 352,705 shares

Expires 2031-09-05

F1 · kind: On November 4, 2025, the Issuer's Board of Directors approved a repricing of the Reporting Person's outstanding stock options granted under the Issuer's 2020 Stock Plan, 2022 Stock Option and Incentive Plan, and 2024 Inducement Plan. The exercise price of eligible options was reduced to $4.53, with all other terms unchanged except that the reduced exercise price is available only if the Reporting Person satisfies the applicable retention period; otherwise, the original exercise price will apply. The transactions reported herein are exempt pursuant to Rules 16b-6(d) and 16b-3 under the Securities Exchange Act of 1934.

F2 · derivative.exercise_date: This stock option vests over four years following the vesting commencement date (September 6, 2021) with 25% of such shares vesting on the first anniversary of the vesting commencement date, and the remaining shares vesting in 36 equal monthly installments, subject to continued service through each vesting date.

SEC source: 0001127602-25-012400 · form4.xml · nonDerivative · entry 1

McArthur James G · CIK 0001763307 · Director · President and CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 113,913

F1 · price: Shares of Common Stock purchased on the open market on April 17, 2025 at prices ranging from $1.335 to $1.36, 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 purchased at each separate price within the range set forth in this footnote.

SEC source: 0001127602-25-011837 · form4.xml · nonDerivative · entry 1

McArthur James G · CIK 0001763307 · Director · President and CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 103,913

F1 · price: Shares of Common Stock purchased on the open market on April 8, 2025 at prices ranging from $1.145 to $1.15, 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 purchased at each separate price within the range set forth in this footnote.

SEC source: 0001127602-25-008359 · form4.xml · derivative · entry 2

McArthur James G · CIK 0001763307 · Director · President and CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 271,875

Underlying: Common Stock · 271,875 shares

Expires 2035-03-02

F3 · derivative.exercise_date: This option shall vest as follows: twenty-five percent (25%) on the one-year anniversary of the Grant Date and the remainder vesting in thirty-six (36) equal monthly installments, subject to the Reporting Person's continued service or employment with the Company on each applicable vesting date.

SEC source: 0001127602-25-008359 · form4.xml · nonDerivative · entry 1

McArthur James G · CIK 0001763307 · Director · President and CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 62,413

F1 · shares: Consists of shares of Common Stock issuable under 60,719 restricted stock units ("RSUs"). Each RSU represents the right to receive one share of Common Stock upon vesting. These RSUs are scheduled to vest in equal annual installments over four years with the first installment vesting on March 3, 2026, subject to the Reporting Person's continued service or employment with the Company on each applicable vesting date.

F2 · balance_after: Includes of 60,719 shares of unvested RSUs.

SEC source: 0001127602-24-007956 · form4.xml · derivative · entry 1

McArthur James G · CIK 0001763307 · Director · President and CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 300,000

Underlying: Common Stock · 300,000 shares

Expires 2034-02-28

F1 · derivative.exercise_date: This option shall vest as follows: twenty-five percent (25%) on the one-year anniversary of the Grant Date and the remainder vesting in thirty-six (36) equal monthly installments, subject to the option recipient's continued service or employment with the Company on each applicable vesting date.

SEC source: 0001127602-23-028801 · form4.xml · nonDerivative · entry 1

McArthur James G · CIK 0001763307 · Director · President and CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 1,694

F1 · price: Shares of Common Stock purchased pursuant to the PepGen Inc. 2022 Employee Stock Purchase Plan ("ESPP"), for the purchase period of June 1, 2023 to November 30, 2023. In accordance with the ESPP, these shares were purchased at a price equal to 85% of the closing price of PepGen's Common Stock on November 30, 2023.

SEC source: 0001127602-23-018472 · form4.xml · derivative · entry 3

McArthur James G · CIK 0001763307 · Director · President and CEO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 325,054

Underlying: Common Stock · 2,381 shares

Expires 2031-03-21

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 · kind: The transactions reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on December 8, 2022.

F3 · derivative.exercise_date: This stock option vests over four years following the vesting commencement date (January 21, 2021) with 25% of such shares vesting on the first anniversary of the vesting commencement date, and the remaining shares vesting in 36 equal monthly installments, subject to continued service through each vesting date.

SEC source: 0001127602-23-018472 · form4.xml · nonDerivative · entry 2

McArthur James G · CIK 0001763307 · Director · President and CEO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 0

F1 · kind: The transactions reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on December 8, 2022.

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $16.00 to $16.10, 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 range set forth in this footnote.

SEC source: 0001127602-23-018472 · form4.xml · nonDerivative · entry 1

McArthur James G · CIK 0001763307 · Director · President and CEO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 2,381

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 · kind: The transactions reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on December 8, 2022.

SEC source: 0001127602-23-018351 · form4.xml · derivative · entry 6

McArthur James G · CIK 0001763307 · Director · President and CEO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 327,435

Underlying: Common Stock · 8,419 shares

Expires 2031-03-21

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 · kind: The transactions reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on December 8, 2022.

F4 · derivative.exercise_date: This stock option vests over four years following the vesting commencement date (January 21, 2021) with 25% of such shares vesting on the first anniversary of the vesting commencement date, and the remaining shares vesting in 36 equal monthly installments, subject to continued service through each vesting date.

SEC source: 0001127602-23-018351 · form4.xml · nonDerivative · entry 4

McArthur James G · CIK 0001763307 · Director · President and CEO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 0

F1 · kind: The transactions reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on December 8, 2022.

F3 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $16.00 to $16.61, 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 set forth in this footnote.

SEC source: 0001127602-23-018351 · form4.xml · nonDerivative · entry 3

McArthur James G · CIK 0001763307 · Director · President and CEO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 8,419

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 · kind: The transactions reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on December 8, 2022.

SEC source: 0001127602-23-018351 · form4.xml · derivative · entry 5

McArthur James G · CIK 0001763307 · Director · President and CEO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 335,854

Underlying: Common Stock · 18,150 shares

Expires 2031-03-21

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 · kind: The transactions reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on December 8, 2022.

F4 · derivative.exercise_date: This stock option vests over four years following the vesting commencement date (January 21, 2021) with 25% of such shares vesting on the first anniversary of the vesting commencement date, and the remaining shares vesting in 36 equal monthly installments, subject to continued service through each vesting date.

SEC source: 0001127602-23-018351 · form4.xml · nonDerivative · entry 2

McArthur James G · CIK 0001763307 · Director · President and CEO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 0

F1 · kind: The transactions reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on December 8, 2022.

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $16.00 to $16.43, 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 set forth in this footnote.

SEC source: 0001127602-23-018351 · form4.xml · nonDerivative · entry 1

McArthur James G · CIK 0001763307 · Director · President and CEO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 18,150

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 · kind: The transactions reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on December 8, 2022.

SEC source: 0001127602-23-018040 · form4.xml · derivative · entry 6

McArthur James G · CIK 0001763307 · Director · President and CEO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 354,004

Underlying: Common Stock · 500 shares

Expires 2031-03-21

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 · kind: The transactions reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on December 8, 2022.

F4 · derivative.exercise_date: This stock option vests over four years following the vesting commencement date (January 21, 2021) with 25% of such shares vesting on the first anniversary of the vesting commencement date, and the remaining shares vesting in 36 equal monthly installments, subject to continued service through each vesting date.

SEC source: 0001127602-23-018040 · form4.xml · nonDerivative · entry 4

McArthur James G · CIK 0001763307 · Director · President and CEO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 0

F1 · kind: The transactions reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on December 8, 2022.

F3 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $16.05 to $16.08, 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 set forth in this footnote.

SEC source: 0001127602-23-018040 · form4.xml · nonDerivative · entry 3

McArthur James G · CIK 0001763307 · Director · President and CEO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 500

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 · kind: The transactions reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on December 8, 2022.

SEC source: 0001127602-23-018040 · form4.xml · derivative · entry 5

McArthur James G · CIK 0001763307 · Director · President and CEO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 354,504

Underlying: Common Stock · 1,800 shares

Expires 2031-03-21

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 · kind: The transactions reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on December 8, 2022.

F4 · derivative.exercise_date: This stock option vests over four years following the vesting commencement date (January 21, 2021) with 25% of such shares vesting on the first anniversary of the vesting commencement date, and the remaining shares vesting in 36 equal monthly installments, subject to continued service through each vesting date.

SEC source: 0001127602-23-018040 · form4.xml · nonDerivative · entry 2

McArthur James G · CIK 0001763307 · Director · President and CEO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 0

F1 · kind: The transactions reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on December 8, 2022.

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $16.00 to $16.14, 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 set forth in this footnote.

SEC source: 0001127602-23-018040 · form4.xml · nonDerivative · entry 1

McArthur James G · CIK 0001763307 · Director · President and CEO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 1,800

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 · kind: The transactions reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on December 8, 2022.

SEC source: 0001127602-23-008382 · form4.xml · derivative · entry 1

McArthur James G · CIK 0001763307 · Director · President and CEO

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 275,000

Underlying: Common Stock · 275,000 shares

Expires 2033-02-28

F1 · derivative.exercise_date: This option shall vest as follows: twenty-five percent (25%) on the one-year anniversary of the Grant Date and the remainder vesting in thirty-six (36) equal monthly installments, subject to the option recipient's continued service or employment with the Company on each applicable vesting date.

SEC source: 0000899243-22-017499 · doc4.xml · derivative · entry 1

McArthur James G · CIK 0001763307 · Director · President and CEO

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 466,095

Underlying: Common Stock · 466,095 shares

Expires 2032-05-05

F1 · derivative.exercise_date: This option shall vest as follows: twenty-five percent (25%) on the one-year anniversary of the Grant Date and the remainder vesting in thirty-six (36) equal monthly installments, subject to the option recipient's continued service or employment with the Company on each applicable vesting date.

SEC source: 0000899243-20-008487 · doc4.xml · derivative · entry 1

McArthur James G · CIK 0001763307 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 15,457

Underlying: Common Stock · 15,457 shares

Expires 2030-03-15

F1 · derivative.exercise_date: The option vests in three equal installments on March 16, 2021, 2022 and 2023.

SEC source: 0001209191-19-035568 · doc4.xml · derivative · entry 3

McArthur James G · CIK 0001763307 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 0

Underlying: Ordinary Shares · 21,000 shares

Expires 2029-01-24

F3 · price: Represents the payment per share received in exchange for the cancellation of each option of $25.50, less the applicable exercise price.

F2 · derivative.exercise_date: In connection with the acquisition by Tungsten Bidco Limited of the entire issued and to be issued share capital of the Issuer on June 7, 2019 by means of a scheme of arrangement under Part 26 of the UK Companies Act 2006, all stock options were cancelled in exchange for a payment equal to $25.50 with respect to each ordinary share subject to the option award, less the applicable exercise price.

F1 · derivative.underlying: The ordinary shares, nominal value GBP 0.01 per share, of Nightstar Therapeutics plc (the "Issuer") may be represented by American Depositary Shares ("ADSs"). Each ADS represents one ordinary share of the Issuer.

SEC source: 0001209191-19-035568 · doc4.xml · derivative · entry 2

McArthur James G · CIK 0001763307 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 0

Underlying: Ordinary Shares · 18,200 shares

Expires 2028-02-27

F3 · price: Represents the payment per share received in exchange for the cancellation of each option of $25.50, less the applicable exercise price.

F2 · derivative.exercise_date: In connection with the acquisition by Tungsten Bidco Limited of the entire issued and to be issued share capital of the Issuer on June 7, 2019 by means of a scheme of arrangement under Part 26 of the UK Companies Act 2006, all stock options were cancelled in exchange for a payment equal to $25.50 with respect to each ordinary share subject to the option award, less the applicable exercise price.

F1 · derivative.underlying: The ordinary shares, nominal value GBP 0.01 per share, of Nightstar Therapeutics plc (the "Issuer") may be represented by American Depositary Shares ("ADSs"). Each ADS represents one ordinary share of the Issuer.

SEC source: 0001209191-19-035568 · doc4.xml · nonDerivative · entry 1

McArthur James G · CIK 0001763307 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 0

F1 · security: The ordinary shares, nominal value GBP 0.01 per share, of Nightstar Therapeutics plc (the "Issuer") may be represented by American Depositary Shares ("ADSs"). Each ADS represents one ordinary share of the Issuer.

SEC source: 0001209191-19-005964 · doc4.xml · derivative · entry 1

McArthur James G · CIK 0001763307 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 21,000

Underlying: Ordinary Shares · 21,000 shares

Expires 2029-01-24

F1 · derivative.exercise_date: This option vests in full on the close of business the day before the 2020 Annual General Meeting of Shareholders.

F2 · derivative.underlying: The ordinary shares, nominal value GBP 0.01 per share, of the Issuer may be represented by American Depositary Shares ("ADSs"). Each ADS represents one ordinary share of the Issuer.