Iwicki Mark T

SEC source: 0001193125-26-272700 · ownership.xml · derivative · entry 1

Iwicki Mark T · CIK 0001415537 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 9,810

Underlying: Common Stock · 9,810 shares

Expires 2036-06-11

F1 · derivative.exercise_date: The shares underlying this option shall vest and become exercisable in full upon the earlier of (i) June 12, 2027 or (ii) the date of the Issuer's next annual meeting of stockholders, subject to the Reporting Person's continued service on such vesting date.

SEC source: 0001193125-26-310978 · ownership.xml · derivative · entry 1

Iwicki Mark T · CIK 0001415537 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 10,826

Underlying: Common Stock · 10,826 shares

Expires 2036-06-11

F1 · shares: This Form 4 amendment is being filed solely to amend the Form 4 filed on June 16, 2026 to correct the number of options awarded to the Reporting Person on June 12, 2026.

F2 · derivative.exercise_date: The shares underlying this option shall vest and become exercisable in full upon the earlier of (i) June 12, 2027 or (ii) the date of the Issuer's next annual meeting of stockholders, subject to the Reporting Person's continued service on such vesting date.

F1 · derivative.underlying_shares: This Form 4 amendment is being filed solely to amend the Form 4 filed on June 16, 2026 to correct the number of options awarded to the Reporting Person on June 12, 2026.

F1 · balance_after: This Form 4 amendment is being filed solely to amend the Form 4 filed on June 16, 2026 to correct the number of options awarded to the Reporting Person on June 12, 2026.

SEC source: 0001193125-26-006351 · ownership.xml · derivative · entry 1

Iwicki Mark T · CIK 0001415537 · Director · Chief Executive Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 4,982,706

Underlying: Common Stock · 4,982,706 shares

Expires 2036-01-05

F1 · derivative.exercise_date: The shares underlying the option shall vest and become exercisable in 36 equal monthly installments commencing from January 5, 2026, subject to the Reporting Person's continued employment through each such vesting date.

SEC source: 0001193125-25-317936 · ownership.xml · derivative · entry 10

Iwicki Mark T · CIK 0001415537 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Shares · 8,500 shares

Expires 2029-06-12

F2 · derivative.exercise_date: This option was cancelled pursuant to the Transaction Agreement in exchange for cash (without interest and net of applicable withholding tax and other applicable deductions) in an amount equal to the product of (i) the amount by which the Offer Consideration exceeds the applicable exercise price per Share of such option and (ii) the aggregate number of Shares underlying such option.

SEC source: 0001193125-25-317936 · ownership.xml · derivative · entry 9

Iwicki Mark T · CIK 0001415537 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Shares · 4,983 shares

Expires 2028-07-20

F2 · derivative.exercise_date: This option was cancelled pursuant to the Transaction Agreement in exchange for cash (without interest and net of applicable withholding tax and other applicable deductions) in an amount equal to the product of (i) the amount by which the Offer Consideration exceeds the applicable exercise price per Share of such option and (ii) the aggregate number of Shares underlying such option.

SEC source: 0001193125-25-317936 · ownership.xml · derivative · entry 8

Iwicki Mark T · CIK 0001415537 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Shares · 5,650 shares

Expires 2027-05-24

F2 · derivative.exercise_date: This option was cancelled pursuant to the Transaction Agreement in exchange for cash (without interest and net of applicable withholding tax and other applicable deductions) in an amount equal to the product of (i) the amount by which the Offer Consideration exceeds the applicable exercise price per Share of such option and (ii) the aggregate number of Shares underlying such option.

SEC source: 0001193125-25-317936 · ownership.xml · derivative · entry 7

Iwicki Mark T · CIK 0001415537 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Shares · 8,631 shares

Expires 2030-06-30

F2 · derivative.exercise_date: This option was cancelled pursuant to the Transaction Agreement in exchange for cash (without interest and net of applicable withholding tax and other applicable deductions) in an amount equal to the product of (i) the amount by which the Offer Consideration exceeds the applicable exercise price per Share of such option and (ii) the aggregate number of Shares underlying such option.

SEC source: 0001193125-25-317936 · ownership.xml · derivative · entry 6

Iwicki Mark T · CIK 0001415537 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Shares · 6,120 shares

Expires 2031-05-28

F2 · derivative.exercise_date: This option was cancelled pursuant to the Transaction Agreement in exchange for cash (without interest and net of applicable withholding tax and other applicable deductions) in an amount equal to the product of (i) the amount by which the Offer Consideration exceeds the applicable exercise price per Share of such option and (ii) the aggregate number of Shares underlying such option.

SEC source: 0001193125-25-317936 · ownership.xml · derivative · entry 5

Iwicki Mark T · CIK 0001415537 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Shares · 16,604 shares

Expires 2032-05-31

F2 · derivative.exercise_date: This option was cancelled pursuant to the Transaction Agreement in exchange for cash (without interest and net of applicable withholding tax and other applicable deductions) in an amount equal to the product of (i) the amount by which the Offer Consideration exceeds the applicable exercise price per Share of such option and (ii) the aggregate number of Shares underlying such option.

SEC source: 0001193125-25-317936 · ownership.xml · derivative · entry 4

Iwicki Mark T · CIK 0001415537 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Shares · 14,414 shares

Expires 2033-06-08

F2 · derivative.exercise_date: This option was cancelled pursuant to the Transaction Agreement in exchange for cash (without interest and net of applicable withholding tax and other applicable deductions) in an amount equal to the product of (i) the amount by which the Offer Consideration exceeds the applicable exercise price per Share of such option and (ii) the aggregate number of Shares underlying such option.

SEC source: 0001193125-25-317936 · ownership.xml · derivative · entry 3

Iwicki Mark T · CIK 0001415537 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Shares · 8,844 shares

Expires 2034-05-07

F2 · derivative.exercise_date: This option was cancelled pursuant to the Transaction Agreement in exchange for cash (without interest and net of applicable withholding tax and other applicable deductions) in an amount equal to the product of (i) the amount by which the Offer Consideration exceeds the applicable exercise price per Share of such option and (ii) the aggregate number of Shares underlying such option.

SEC source: 0001193125-25-317936 · ownership.xml · derivative · entry 2

Iwicki Mark T · CIK 0001415537 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Shares · 13,193 shares

Expires 2035-05-22

F2 · derivative.exercise_date: This option was cancelled pursuant to the Transaction Agreement in exchange for cash (without interest and net of applicable withholding tax and other applicable deductions) in an amount equal to the product of (i) the amount by which the Offer Consideration exceeds the applicable exercise price per Share of such option and (ii) the aggregate number of Shares underlying such option.

SEC source: 0001193125-25-317936 · ownership.xml · nonDerivative · entry 1

Iwicki Mark T · CIK 0001415537 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

F1 · price: On September 29, 2025, Merus N.V. (the "Issuer") entered into a transaction agreement (as it may be amended, supplemented or otherwise modified from time to time, the "Transaction Agreement") with Genmab A/S ("Genmab") and its wholly owned subsidiary, Genmab Holding II B.V. (the "Purchaser"). Pursuant to the terms of the Transaction Agreement, the Purchaser commenced a tender offer for all the issued and outstanding common shares, par value EUR 0.09 per share (the "Shares"), of the Issuer (the "Offer"), and, on December 12, 2025 (the "Acceptance Time"), the Purchaser accepted all of the Shares that were validly tendered and not properly withdrawn pursuant to the Offer as of the Acceptance Time, including the Shares tendered by the reporting person, in exchange for a cash payment equal to $97.00 per Share, without interest and less applicable withholding taxes (the "Offer Consideration"), which Offer Consideration will be paid as soon as practicable following the Acceptance Time.

SEC source: 0001193125-25-312115 · ownership.xml · derivative · entry 9

Iwicki Mark T · CIK 0001415537 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 76,227 shares

Expires 2028-10-18

F4 · price: Pursuant to the Merger Agreement, at the Effective Time, each compensatory option to purchase shares of Company Common Stock (each, a "Company Option") reported in this Form 4, whether or not vested, was deemed fully vested and was cancelled and converted into the right to receive a cash payment equal to the product of the excess of the Closing Consideration over the per share exercise price of such Company Option, multiplied by the total number of shares of Company Common Stock subject to such Company Option immediately prior to the Effective Time, plus one CVR for each share of Company Common Stock subject to such Company Option immediately prior to the Effective Time.

F4 · derivative.exercise_date: Pursuant to the Merger Agreement, at the Effective Time, each compensatory option to purchase shares of Company Common Stock (each, a "Company Option") reported in this Form 4, whether or not vested, was deemed fully vested and was cancelled and converted into the right to receive a cash payment equal to the product of the excess of the Closing Consideration over the per share exercise price of such Company Option, multiplied by the total number of shares of Company Common Stock subject to such Company Option immediately prior to the Effective Time, plus one CVR for each share of Company Common Stock subject to such Company Option immediately prior to the Effective Time.

SEC source: 0001193125-25-312115 · ownership.xml · derivative · entry 8

Iwicki Mark T · CIK 0001415537 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 11,493 shares

Expires 2029-01-16

F4 · price: Pursuant to the Merger Agreement, at the Effective Time, each compensatory option to purchase shares of Company Common Stock (each, a "Company Option") reported in this Form 4, whether or not vested, was deemed fully vested and was cancelled and converted into the right to receive a cash payment equal to the product of the excess of the Closing Consideration over the per share exercise price of such Company Option, multiplied by the total number of shares of Company Common Stock subject to such Company Option immediately prior to the Effective Time, plus one CVR for each share of Company Common Stock subject to such Company Option immediately prior to the Effective Time.

F4 · derivative.exercise_date: Pursuant to the Merger Agreement, at the Effective Time, each compensatory option to purchase shares of Company Common Stock (each, a "Company Option") reported in this Form 4, whether or not vested, was deemed fully vested and was cancelled and converted into the right to receive a cash payment equal to the product of the excess of the Closing Consideration over the per share exercise price of such Company Option, multiplied by the total number of shares of Company Common Stock subject to such Company Option immediately prior to the Effective Time, plus one CVR for each share of Company Common Stock subject to such Company Option immediately prior to the Effective Time.

SEC source: 0001193125-25-312115 · ownership.xml · derivative · entry 7

Iwicki Mark T · CIK 0001415537 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 70,587 shares

Expires 2029-04-26

F4 · price: Pursuant to the Merger Agreement, at the Effective Time, each compensatory option to purchase shares of Company Common Stock (each, a "Company Option") reported in this Form 4, whether or not vested, was deemed fully vested and was cancelled and converted into the right to receive a cash payment equal to the product of the excess of the Closing Consideration over the per share exercise price of such Company Option, multiplied by the total number of shares of Company Common Stock subject to such Company Option immediately prior to the Effective Time, plus one CVR for each share of Company Common Stock subject to such Company Option immediately prior to the Effective Time.

F4 · derivative.exercise_date: Pursuant to the Merger Agreement, at the Effective Time, each compensatory option to purchase shares of Company Common Stock (each, a "Company Option") reported in this Form 4, whether or not vested, was deemed fully vested and was cancelled and converted into the right to receive a cash payment equal to the product of the excess of the Closing Consideration over the per share exercise price of such Company Option, multiplied by the total number of shares of Company Common Stock subject to such Company Option immediately prior to the Effective Time, plus one CVR for each share of Company Common Stock subject to such Company Option immediately prior to the Effective Time.

SEC source: 0001193125-25-312115 · ownership.xml · derivative · entry 6

Iwicki Mark T · CIK 0001415537 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 13,000 shares

Expires 2030-06-01

F4 · price: Pursuant to the Merger Agreement, at the Effective Time, each compensatory option to purchase shares of Company Common Stock (each, a "Company Option") reported in this Form 4, whether or not vested, was deemed fully vested and was cancelled and converted into the right to receive a cash payment equal to the product of the excess of the Closing Consideration over the per share exercise price of such Company Option, multiplied by the total number of shares of Company Common Stock subject to such Company Option immediately prior to the Effective Time, plus one CVR for each share of Company Common Stock subject to such Company Option immediately prior to the Effective Time.

F4 · derivative.exercise_date: Pursuant to the Merger Agreement, at the Effective Time, each compensatory option to purchase shares of Company Common Stock (each, a "Company Option") reported in this Form 4, whether or not vested, was deemed fully vested and was cancelled and converted into the right to receive a cash payment equal to the product of the excess of the Closing Consideration over the per share exercise price of such Company Option, multiplied by the total number of shares of Company Common Stock subject to such Company Option immediately prior to the Effective Time, plus one CVR for each share of Company Common Stock subject to such Company Option immediately prior to the Effective Time.

SEC source: 0001193125-25-312115 · ownership.xml · derivative · entry 5

Iwicki Mark T · CIK 0001415537 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 13,000 shares

Expires 2031-06-01

F4 · price: Pursuant to the Merger Agreement, at the Effective Time, each compensatory option to purchase shares of Company Common Stock (each, a "Company Option") reported in this Form 4, whether or not vested, was deemed fully vested and was cancelled and converted into the right to receive a cash payment equal to the product of the excess of the Closing Consideration over the per share exercise price of such Company Option, multiplied by the total number of shares of Company Common Stock subject to such Company Option immediately prior to the Effective Time, plus one CVR for each share of Company Common Stock subject to such Company Option immediately prior to the Effective Time.

F4 · derivative.exercise_date: Pursuant to the Merger Agreement, at the Effective Time, each compensatory option to purchase shares of Company Common Stock (each, a "Company Option") reported in this Form 4, whether or not vested, was deemed fully vested and was cancelled and converted into the right to receive a cash payment equal to the product of the excess of the Closing Consideration over the per share exercise price of such Company Option, multiplied by the total number of shares of Company Common Stock subject to such Company Option immediately prior to the Effective Time, plus one CVR for each share of Company Common Stock subject to such Company Option immediately prior to the Effective Time.

SEC source: 0001193125-25-312115 · ownership.xml · derivative · entry 4

Iwicki Mark T · CIK 0001415537 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 15,000 shares

Expires 2032-06-02

F4 · price: Pursuant to the Merger Agreement, at the Effective Time, each compensatory option to purchase shares of Company Common Stock (each, a "Company Option") reported in this Form 4, whether or not vested, was deemed fully vested and was cancelled and converted into the right to receive a cash payment equal to the product of the excess of the Closing Consideration over the per share exercise price of such Company Option, multiplied by the total number of shares of Company Common Stock subject to such Company Option immediately prior to the Effective Time, plus one CVR for each share of Company Common Stock subject to such Company Option immediately prior to the Effective Time.

F4 · derivative.exercise_date: Pursuant to the Merger Agreement, at the Effective Time, each compensatory option to purchase shares of Company Common Stock (each, a "Company Option") reported in this Form 4, whether or not vested, was deemed fully vested and was cancelled and converted into the right to receive a cash payment equal to the product of the excess of the Closing Consideration over the per share exercise price of such Company Option, multiplied by the total number of shares of Company Common Stock subject to such Company Option immediately prior to the Effective Time, plus one CVR for each share of Company Common Stock subject to such Company Option immediately prior to the Effective Time.

SEC source: 0001193125-25-312115 · ownership.xml · derivative · entry 3

Iwicki Mark T · CIK 0001415537 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 15,000 shares

Expires 2033-06-23

F4 · price: Pursuant to the Merger Agreement, at the Effective Time, each compensatory option to purchase shares of Company Common Stock (each, a "Company Option") reported in this Form 4, whether or not vested, was deemed fully vested and was cancelled and converted into the right to receive a cash payment equal to the product of the excess of the Closing Consideration over the per share exercise price of such Company Option, multiplied by the total number of shares of Company Common Stock subject to such Company Option immediately prior to the Effective Time, plus one CVR for each share of Company Common Stock subject to such Company Option immediately prior to the Effective Time.

F4 · derivative.exercise_date: Pursuant to the Merger Agreement, at the Effective Time, each compensatory option to purchase shares of Company Common Stock (each, a "Company Option") reported in this Form 4, whether or not vested, was deemed fully vested and was cancelled and converted into the right to receive a cash payment equal to the product of the excess of the Closing Consideration over the per share exercise price of such Company Option, multiplied by the total number of shares of Company Common Stock subject to such Company Option immediately prior to the Effective Time, plus one CVR for each share of Company Common Stock subject to such Company Option immediately prior to the Effective Time.

SEC source: 0001193125-25-312115 · ownership.xml · derivative · entry 2

Iwicki Mark T · CIK 0001415537 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 26,000 shares

Expires 2034-06-08

F4 · price: Pursuant to the Merger Agreement, at the Effective Time, each compensatory option to purchase shares of Company Common Stock (each, a "Company Option") reported in this Form 4, whether or not vested, was deemed fully vested and was cancelled and converted into the right to receive a cash payment equal to the product of the excess of the Closing Consideration over the per share exercise price of such Company Option, multiplied by the total number of shares of Company Common Stock subject to such Company Option immediately prior to the Effective Time, plus one CVR for each share of Company Common Stock subject to such Company Option immediately prior to the Effective Time.

F4 · derivative.exercise_date: Pursuant to the Merger Agreement, at the Effective Time, each compensatory option to purchase shares of Company Common Stock (each, a "Company Option") reported in this Form 4, whether or not vested, was deemed fully vested and was cancelled and converted into the right to receive a cash payment equal to the product of the excess of the Closing Consideration over the per share exercise price of such Company Option, multiplied by the total number of shares of Company Common Stock subject to such Company Option immediately prior to the Effective Time, plus one CVR for each share of Company Common Stock subject to such Company Option immediately prior to the Effective Time.

SEC source: 0001193125-25-312115 · ownership.xml · nonDerivative · entry 1

Iwicki Mark T · CIK 0001415537 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

F1 · shares: This Form 4 reports securities disposed of pursuant to the terms of the Agreement and Plan of Merger (the "Merger Agreement"), dated as of October 9, 2025, among the Issuer, Novo Nordisk A/S, a Danish aktieselskab ("Novo"), and NN Invest Sub, Inc, a Delaware corporation and a direct or indirect wholly owned subsidiary of Novo ("Merger Sub"), pursuant to which Merger Sub merged with and into the Issuer (the "Merger"), effective as of December 9, 2025 (such date and time of such Merger, the "Effective Time"), with the Issuer surviving the Merger as a direct or indirect wholly owned subsidiary of Novo.

F2 · shares: Represents restricted stock units ("Company RSUs") granted to the Reporting Person. Each Company RSU represented a contingent right to receive one share of common stock of the Issuer ("Company Common Stock") upon vesting of the Company RSU.

F3 · price: Pursuant to the Merger Agreement, at the Effective Time, each Company RSU reported in this Form 4 was deemed fully vested and cancelled and was converted into the right of the Reporting Person to receive in respect of each such Company RSU (i) cash in an amount equal to $54.00 (the "Closing Consideration") and (ii) one contractual contingent value right (a "CVR") representing the right to receive $6.00 in cash, if a specified milestone is achieved, pursuant to the CVR Agreement (as defined in the Merger Agreement), without interest and subject to any withholding taxes.

SEC source: 0001415537-25-000004 · form4-10242025_081010.xml · nonDerivative · entry 1

Iwicki Mark T · CIK 0001415537 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 103,540

F1 · price: The price reported is a weighted average price. These shares were sold in multiple transactions at prices ranging from $0.78 to $0.85, 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 to this Form 4.

F2 · balance_after: Includes 103,540 unvested RSUs.

SEC source: 0001193125-25-251994 · ownership.xml · derivative · entry 1

Iwicki Mark T · CIK 0001415537 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 53,521

Underlying: Common Stock · 53,521 shares

Expires 2035-10-22

F1 · derivative.exercise_date: The shares underlying this option shall vest and become exercisable in full upon the earlier of (i) October 23, 2026 or (ii) the date of the Issuer's next annual meeting of stockholders, subject to the Reporting Person's continued service on such vesting date.

SEC source: 0001415889-25-021822 · form4-08142025_080855.xml · derivative · entry 2

Iwicki Mark T · CIK 0001415537 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 83,296 shares

Expires not disclosed

F3 · derivative.exercise_price: Represents payment of the liquidation distribution of $5.35 per share less the exercise price of such options.

F1 · kind: Transaction reported is a cancellation of shares of common stock in connection with the dissolution of the Issuer.

F3 · derivative.exercise_date: Represents payment of the liquidation distribution of $5.35 per share less the exercise price of such options.

F3 · derivative.expiration_date: Represents payment of the liquidation distribution of $5.35 per share less the exercise price of such options.

SEC source: 0001415889-25-021822 · form4-08142025_080855.xml · nonDerivative · entry 1

Iwicki Mark T · CIK 0001415537 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

F1 · kind: Transaction reported is a cancellation of shares of common stock in connection with the dissolution of the Issuer.

F2 · price: The reporting person received a liquidation distribution of $5.35 per share of Common Stock from Issuer.

SEC source: 0001415889-25-018317 · form4-06262025_080601.xml · nonDerivative · entry 1

Iwicki Mark T · CIK 0001415537 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 258,433

F1 · shares: This sale was made pursuant to a 10b5-1 trading plan adopted by the Reporting Person on November 9, 2020 to cover tax withholding obligations in connection with the vesting and settlement of the Reporting Person's restricted stock units ("RSUs") granted on June 22, 2023.

F2 · price: The price reported is a weighted average price. These shares were sold in multiple transactions at prices ranging from $3.87 to $4.12, 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 to this Form 4.

F3 · balance_after: Includes 103,540 unvested RSUs.

SEC source: 0001415889-25-017615 · form4-06172025_080611.xml · derivative · entry 2

Iwicki Mark T · CIK 0001415537 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 5,450

Underlying: Common Stock · 5,450 shares

Expires 2035-06-14

F3 · derivative.exercise_date: This option was granted on June 15, 2025 and vests as to 100% of the shares underlying the grant on the earlier of (i) June 15, 2026 or (ii) the date of the first annual meeting of stockholders occurring in 2026.

SEC source: 0001415889-25-017615 · form4-06172025_080611.xml · nonDerivative · entry 1

Iwicki Mark T · CIK 0001415537 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 271,660

F1 · security: Grant of restricted stock units ("RSUs") under the Issuer's Amended and Restated 2017 Equity Incentive Plan. Each RSU represents a contingent right to receive one share of the Issuer's common stock. Subject to the reporting person's continued service, the RSUs will vest as to 100% of the shares underlying the grant on the earlier of (i) June 15, 2026 or (ii) the date of the first annual meeting of stockholders occurring in 2026.

F2 · balance_after: Includes 156,492 unvested RSUs.

SEC source: 0001415889-25-015677 · form4-06042025_080601.xml · nonDerivative · entry 1

Iwicki Mark T · CIK 0001415537 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 269,210

F1 · shares: This sale was made pursuant to a 10b5-1 trading plan adopted by the Reporting Person on November 9, 2020 to cover tax withholding obligations in connection with the vesting and settlement of the Reporting Person's restricted stock units ("RSUs") granted on May 31, 2023.

F2 · price: The price reported is a weighted average price. These shares were sold in multiple transactions at prices ranging from $3.52 to $4.05, 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 to this Form 4.

F3 · balance_after: Includes 154,042 unvested RSUs.

SEC source: 0000950170-25-082309 · ownership.xml · nonDerivative · entry 1

Iwicki Mark T · CIK 0001415537 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 9,398

F1 · shares: These shares are represented by restricted stock units (the "RSUs"). Each RSU represents a contingent right to receive one share of Common Stock of the Issuer. The RSUs shall vest in full on the earlier of (i) June 3, 2026, and (ii) the next annual meeting of the Company's stockholders, subject to the director's continued service on the Board.

SEC source: 0001104659-25-056986 · tm2517328-2_4aseq1.xml · nonDerivative · entry 1

Iwicki Mark T · CIK 0001415537 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 269,210

F1 · shares: This sale was made pursuant to a 10b5-1 trading plan adopted by the Reporting Person on November 9, 2020 to cover tax withholding obligations in connection with the vesting and settlement of the Reporting Person's restricted stock units ("RSUs") granted on May 31, 2023.

F3 · price: The price reported is a weighted average price. These shares were sold in multiple transactions at prices ranging from $3.52 to $4.05, 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 to this Form 4.

F2 · acquired: This amendment is being filed solely to correct the nature of the transaction reported in Column 4 of Table I of the Form 4 filed by the Reporting Person on June 4, 2025. As reported in this amendment, such transaction resulted in a "disposition" of common stock by the Reporting Person and not an "acquisition" as previously reported.

F4 · balance_after: Includes 154,042 unvested RSUs.

SEC source: 0000950170-25-077380 · ownership.xml · derivative · entry 1

Iwicki Mark T · CIK 0001415537 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 13,193

Underlying: Common Shares · 13,193 shares

Expires 2035-05-22

F1 · derivative.exercise_date: Options vest over a one-year period commencing on May 22, 2025 in 12 equal monthly installments.

SEC source: 0000950170-25-028253 · ownership.xml · derivative · entry 6

Iwicki Mark T · CIK 0001415537 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 25,534

Underlying: Common Stock · 25,534 shares

Expires 2034-03-24

F3 · derivative.exercise_price: The exercise price of the option is $2.54 per share, representing the fair market value per share of the Issuer's Common Stock on the Repricing Date; provided that in the event (i) the option is exercised prior to the one-year anniversary of the Repricing Date, (ii) the Reporting Person's employment is terminated by the Company prior to the one-year anniversary of the Repricing Date due to Cause (as defined in the 2024 Plan) or (iii) the Reporting Person resigns for any reason prior to the one-year anniversary of the Repricing Date, the exercise price will be increased to the exercise price of the cancelled option in exchange for which this option was granted.

F1 · kind: On February 24, 2025, the Issuer's board of directors approved an option repricing ("Repricing Date"). All of the other terms of the options remain unchanged. Such transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act, as applicable.

F1 · price: On February 24, 2025, the Issuer's board of directors approved an option repricing ("Repricing Date"). All of the other terms of the options remain unchanged. Such transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act, as applicable.

F2 · derivative.exercise_date: This stock option award was issued pursuant to the Q32 Bio Inc. 2017 Stock Option and Grant Plan (the "2017 Plan") or the Q32 Bio Inc. 2024 Stock Option and Incentive Plan (the "2024 Plan"), as applicable, and becomes exercisable in accordance with the vesting schedule specified in the award agreement and as previously reported on applicable Form 4, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date.

SEC source: 0000950170-25-028253 · ownership.xml · derivative · entry 5

Iwicki Mark T · CIK 0001415537 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 25,534 shares

Expires 2034-03-24

F1 · kind: On February 24, 2025, the Issuer's board of directors approved an option repricing ("Repricing Date"). All of the other terms of the options remain unchanged. Such transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act, as applicable.

F1 · price: On February 24, 2025, the Issuer's board of directors approved an option repricing ("Repricing Date"). All of the other terms of the options remain unchanged. Such transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act, as applicable.

F2 · derivative.exercise_date: This stock option award was issued pursuant to the Q32 Bio Inc. 2017 Stock Option and Grant Plan (the "2017 Plan") or the Q32 Bio Inc. 2024 Stock Option and Incentive Plan (the "2024 Plan"), as applicable, and becomes exercisable in accordance with the vesting schedule specified in the award agreement and as previously reported on applicable Form 4, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date.

SEC source: 0000950170-25-028253 · ownership.xml · derivative · entry 4

Iwicki Mark T · CIK 0001415537 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 7,615

Underlying: Common Stock · 7,615 shares

Expires 2031-12-16

F3 · derivative.exercise_price: The exercise price of the option is $2.54 per share, representing the fair market value per share of the Issuer's Common Stock on the Repricing Date; provided that in the event (i) the option is exercised prior to the one-year anniversary of the Repricing Date, (ii) the Reporting Person's employment is terminated by the Company prior to the one-year anniversary of the Repricing Date due to Cause (as defined in the 2024 Plan) or (iii) the Reporting Person resigns for any reason prior to the one-year anniversary of the Repricing Date, the exercise price will be increased to the exercise price of the cancelled option in exchange for which this option was granted.

F1 · kind: On February 24, 2025, the Issuer's board of directors approved an option repricing ("Repricing Date"). All of the other terms of the options remain unchanged. Such transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act, as applicable.

F1 · price: On February 24, 2025, the Issuer's board of directors approved an option repricing ("Repricing Date"). All of the other terms of the options remain unchanged. Such transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act, as applicable.

F2 · derivative.exercise_date: This stock option award was issued pursuant to the Q32 Bio Inc. 2017 Stock Option and Grant Plan (the "2017 Plan") or the Q32 Bio Inc. 2024 Stock Option and Incentive Plan (the "2024 Plan"), as applicable, and becomes exercisable in accordance with the vesting schedule specified in the award agreement and as previously reported on applicable Form 4, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date.

SEC source: 0000950170-25-028253 · ownership.xml · derivative · entry 3

Iwicki Mark T · CIK 0001415537 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 7,615 shares

Expires 2031-12-16

F1 · kind: On February 24, 2025, the Issuer's board of directors approved an option repricing ("Repricing Date"). All of the other terms of the options remain unchanged. Such transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act, as applicable.

F1 · price: On February 24, 2025, the Issuer's board of directors approved an option repricing ("Repricing Date"). All of the other terms of the options remain unchanged. Such transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act, as applicable.

F2 · derivative.exercise_date: This stock option award was issued pursuant to the Q32 Bio Inc. 2017 Stock Option and Grant Plan (the "2017 Plan") or the Q32 Bio Inc. 2024 Stock Option and Incentive Plan (the "2024 Plan"), as applicable, and becomes exercisable in accordance with the vesting schedule specified in the award agreement and as previously reported on applicable Form 4, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date.

SEC source: 0000950170-25-028253 · ownership.xml · derivative · entry 2

Iwicki Mark T · CIK 0001415537 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 37,222

Underlying: Common Stock · 37,222 shares

Expires 2031-01-21

F3 · derivative.exercise_price: The exercise price of the option is $2.54 per share, representing the fair market value per share of the Issuer's Common Stock on the Repricing Date; provided that in the event (i) the option is exercised prior to the one-year anniversary of the Repricing Date, (ii) the Reporting Person's employment is terminated by the Company prior to the one-year anniversary of the Repricing Date due to Cause (as defined in the 2024 Plan) or (iii) the Reporting Person resigns for any reason prior to the one-year anniversary of the Repricing Date, the exercise price will be increased to the exercise price of the cancelled option in exchange for which this option was granted.

F1 · kind: On February 24, 2025, the Issuer's board of directors approved an option repricing ("Repricing Date"). All of the other terms of the options remain unchanged. Such transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act, as applicable.

F1 · price: On February 24, 2025, the Issuer's board of directors approved an option repricing ("Repricing Date"). All of the other terms of the options remain unchanged. Such transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act, as applicable.

F2 · derivative.exercise_date: This stock option award was issued pursuant to the Q32 Bio Inc. 2017 Stock Option and Grant Plan (the "2017 Plan") or the Q32 Bio Inc. 2024 Stock Option and Incentive Plan (the "2024 Plan"), as applicable, and becomes exercisable in accordance with the vesting schedule specified in the award agreement and as previously reported on applicable Form 4, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date.

SEC source: 0000950170-25-028253 · ownership.xml · derivative · entry 1

Iwicki Mark T · CIK 0001415537 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 37,222 shares

Expires 2031-01-21

F1 · kind: On February 24, 2025, the Issuer's board of directors approved an option repricing ("Repricing Date"). All of the other terms of the options remain unchanged. Such transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act, as applicable.

F1 · price: On February 24, 2025, the Issuer's board of directors approved an option repricing ("Repricing Date"). All of the other terms of the options remain unchanged. Such transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act, as applicable.

F2 · derivative.exercise_date: This stock option award was issued pursuant to the Q32 Bio Inc. 2017 Stock Option and Grant Plan (the "2017 Plan") or the Q32 Bio Inc. 2024 Stock Option and Incentive Plan (the "2024 Plan"), as applicable, and becomes exercisable in accordance with the vesting schedule specified in the award agreement and as previously reported on applicable Form 4, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date.

SEC source: 0000950170-25-026627 · ownership.xml · derivative · entry 1

Iwicki Mark T · CIK 0001415537 · Director · Chief Executive Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 602,346

Underlying: Common Stock · 602,346 shares

Expires 2035-02-14

F1 · derivative.exercise_date: The options will vest and become exercisable in 48 substantially equal monthly installments beginning on March 21, 2025, subject to the Reporting Person's continued employment through such date.

SEC source: 0000950170-25-093441 · ownership.xml · derivative · entry 1

Iwicki Mark T · CIK 0001415537 · Director · Chief Executive Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 602,346

Underlying: Common Stock · 602,346 shares

Expires 2035-02-21

F1 · derivative.exercise_price: The Reporting Person's Form 4 filed with the SEC on February 25, 2025 inadvertently reported the incorrect exercise price and expiration date with respect to the stock option award originally granted on February 21, 2025 (the "Option Award"). This amendment is being filed solely to correct the exercise price and expiration date of the Option Award.

F2 · derivative.exercise_date: The options will vest and become exercisable in 48 substantially equal monthly installments beginning on March 21, 2025, subject to the Reporting Person's continued employment through such date.

F1 · derivative.expiration_date: The Reporting Person's Form 4 filed with the SEC on February 25, 2025 inadvertently reported the incorrect exercise price and expiration date with respect to the stock option award originally granted on February 21, 2025 (the "Option Award"). This amendment is being filed solely to correct the exercise price and expiration date of the Option Award.

SEC source: 0000950170-25-023600 · ownership.xml · derivative · entry 2

Iwicki Mark T · CIK 0001415537 · Director · Chief Executive Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 1,794,291

Underlying: Common Stock · 1,794,291 shares

Expires 2035-02-17

F1 · derivative.exercise_date: The options will vest and become exercisable in 48 substantially equal monthly installments beginning on March 12, 2025, subject to the Reporting Person's continued employment through such date.

SEC source: 0000950170-25-023600 · ownership.xml · derivative · entry 1

Iwicki Mark T · CIK 0001415537 · Director · Chief Executive Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 4,373,857

Underlying: Common Stock · 4,373,857 shares

Expires 2035-02-14

F1 · derivative.exercise_date: The options will vest and become exercisable in 48 substantially equal monthly installments beginning on March 12, 2025, subject to the Reporting Person's continued employment through such date.

SEC source: 0001415889-25-001060 · form4-01082025_010156.xml · derivative · entry 3

Iwicki Mark T · CIK 0001415537 · Director · CHIEF EXECUTIVE OFFICER

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 99,500

Underlying: Common Stock · 99,500 shares

Expires 2035-01-05

F5 · derivative.exercise_date: This option was granted on January 6, 2025 and vests over four years beginning on the vesting commencement date of January 6, 2025, with 1/48th the shares underlying the option vesting at the end of each successive one-month period thereafter until January 6, 2029, subject to the Reporting Person's continued employment with the Issuer.

SEC source: 0001415889-25-001060 · form4-01082025_010156.xml · nonDerivative · entry 2

Iwicki Mark T · CIK 0001415537 · Director · CHIEF EXECUTIVE OFFICER

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 280,076

F3 · shares: This sale was made pursuant to a 10b5-1 trading plan to cover tax withholding obligations in connection with the vesting and settlement of the Reporting Person's RSUs granted on January 4, 2023 and January 4, 2024.

F4 · price: The price reported is a weighted average price. These shares were sold in multiple transactions at prices ranging from $7.48 to $7.63, 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 to this Form 4.

F2 · balance_after: Includes 194,739 unvested RSUs.

SEC source: 0001415889-25-001060 · form4-01082025_010156.xml · nonDerivative · entry 1

Iwicki Mark T · CIK 0001415537 · Director · CHIEF EXECUTIVE OFFICER

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 285,855

F1 · security: Grant of restricted stock units ("RSUs") under the Issuer's Amended and Restated 2017 Equity Incentive Plan. Each RSU represents a contingent right to receive one share of the Issuer's common stock. Subject to the Reporting Person's continued employment with the Issuer, the RSUs will vest as to 1/3 of the shares underlying the RSUs on January 6, 2026, as to 1/3 of the shares underlying the RSUs on January 6, 2027 and as to the final 1/3 of shares underlying the RSUs on January 6, 2028.

F2 · balance_after: Includes 194,739 unvested RSUs.

SEC source: 0001415889-24-018374 · form4-06272024_080604.xml · nonDerivative · entry 1

Iwicki Mark T · CIK 0001415537 · Director · CHIEF EXECUTIVE OFFICER

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 263,755

F1 · shares: This sale was made pursuant to a 10b5-1 trading plan adopted by the Reporting Person on November 9, 2020 to cover tax withholding obligations in connection with the vesting and settlement of the Reporting Person's restricted stock units ("RSUs") granted on June 22, 2023.

F2 · price: The price reported is a weighted average price. These shares were sold in multiple transactions at prices ranging from $4.50 to $5.09, 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 to this Form 4.

F3 · balance_after: Includes 191,304 unvested RSUs.

SEC source: 0000950170-24-072075 · ownership.xml · derivative · entry 1

Iwicki Mark T · CIK 0001415537 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 26,000

Underlying: Common Stock · 26,000 shares

Expires 2034-06-07

F1 · derivative.exercise_date: This option shall vest in full on the earlier of (i) June 7, 2025, and (ii) the next annual meeting of the Company's stockholders, subject to the director's continued service on the Board.

SEC source: 0001415889-24-016217 · form4-06102024_080630.xml · derivative · entry 1

Iwicki Mark T · CIK 0001415537 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 20,000

Underlying: Common Stock · 20,000 shares

Expires 2034-06-05

F1 · derivative.exercise_date: The option will vest in full on the earlier of (a) June 6, 2025 and (b) the next annual meeting of the Issuer's stockholders, subject to the Reporting Person's provision of service to the Issuer on the vesting date.

SEC source: 0001415889-24-016055 · form4-06072024_060608.xml · derivative · entry 1

Iwicki Mark T · CIK 0001415537 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 12,500

Underlying: Common Stock · 12,500 shares

Expires 2034-06-04

F1 · derivative.exercise_date: The shares subject to this option will vest and become exercisable in full on the earlier of (i) June 5, 2025 or (ii) the next annual meeting of the Issuer's stockholders, subject to the Reporting Person's continued service through the applicable vesting date.