Geoff Mcdonough - 09 Feb 2026 Form 4 Insider Report for Generation Bio Co. (GBIO)

Reporting relationship: Director
Issuer ticker: GBIO
Reported as of: 09 Feb 2026
Net transaction value: $0
SEC form: 4
Accepted by SEC: 09 Feb 2026, 17:36:24 UTC
Prior SEC filing: 04 Feb 2026
Source filing: View source filing
Reporting owner signature: /s/ Shawna-Gay White, Attorney-in-Fact

Key filing fact

Geoff Mcdonough filed Form 4 for Generation Bio Co. (GBIO) on 09 Feb 2026.

Key facts

This page summarizes Geoff Mcdonough's Form 4 filing for Generation Bio Co. (GBIO).
10 reported transactions and 7 derivative rows are listed below.
Accepted by SEC: 09 Feb 2026, 17:36.

Change

Previous filing in this sequence was filed on 04 Feb 2026.
Current net transaction value: $0.

Research use

This tells you what this filing adds before you inspect full transaction and derivative tables.
You can trace every row back to the original SEC filing document.

Evidence

Filed on Form 4

Ownership activity is grounded in SEC Form 4 disclosures.

View source filing

Reporting Owners (1)

CIK 0001732701 Primary reporting owner

MCDONOUGH GEOFF

Relationship: Director
Address: C/O GENERATION BIO CO., 301 BINNEY ST, SUITE 401, CAMBRIDGE
Signature: /s/ Shawna-Gay White, Attorney-in-Fact
Signature date: 09 Feb 2026

Reported non-derivative transactions

Shares, units, or other non-derivative securities reported in this filing.

GBIO transaction

Common Stock

Disposition pursuant to a tender of shares in a change of control transaction

Transaction value
Shares: -138,492
Change %: -100%
Price
Shares after: 0
Date: 09 Feb 2026
Ownership: Direct
Footnotes: F1, F2

GBIO transaction

Common Stock

Disposition pursuant to a tender of shares in a change of control transaction

Transaction value
Shares: -22,646
Change %: -100%
Price
Shares after: 0
Date: 09 Feb 2026
Ownership: By 2018 Trust
Footnotes: F1, F2, F3

GBIO transaction

Common Stock

Disposition pursuant to a tender of shares in a change of control transaction

Transaction value
Shares: -27,500
Change %: -100%
Price
Shares after: 0
Date: 09 Feb 2026
Ownership: By 2020 Trust
Footnotes: F1, F2, F4

Reported derivative securities

Options, warrants, convertible securities, or similar derivative positions disclosed in the filing.

GBIO transaction Derivative

Stock Option (right to buy)

Disposed to Issuer

Transaction value
Shares: -19,903
Change %: -100%
Price
Shares after: 0
Date: 09 Feb 2026
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 19,903
Exercise price: $51.58
Footnotes: F5

GBIO transaction Derivative

Stock Option (right to buy)

Disposed to Issuer

Transaction value
Shares: -25,099
Change %: -100%
Price
Shares after: 0
Date: 09 Feb 2026
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 25,099
Exercise price: $302.50
Footnotes: F5

GBIO transaction Derivative

Stock Option (right to buy)

Disposed to Issuer

Transaction value
Shares: -37,499
Change %: -100%
Price
Shares after: 0
Date: 09 Feb 2026
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 37,499
Exercise price: $64.90
Footnotes: F5

GBIO transaction Derivative

Stock Option (right to buy)

Disposed to Issuer

Transaction value
Shares: -50,624
Change %: -100%
Price
Shares after: 0
Date: 09 Feb 2026
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 50,624
Exercise price: $18.60
Footnotes: F5

GBIO transaction Derivative

Stock Option (right to buy)

Disposed to Issuer

Transaction value
Shares: -90,168
Change %: -100%
Price
Shares after: 0
Date: 09 Feb 2026
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 90,168
Exercise price: $9.26
Footnotes: F5

GBIO transaction Derivative

Stock Option (right to buy)

Disposed to Issuer

Transaction value
Shares: -16,874
Change %: -100%
Price
Shares after: 0
Date: 09 Feb 2026
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 16,874
Exercise price: $47.05
Footnotes: F5

GBIO transaction Derivative

Stock Option (right to buy)

Disposed to Issuer

Transaction value
Shares: -24,046
Change %: -100%
Price
Shares after: 0
Date: 09 Feb 2026
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 24,046
Exercise price: $13.90
Footnotes: F5

^* marks a reported price that did not pass the local price check.

Additional SEC filing notes

Filing notes and footnotes

Section 16 status

Geoff Mcdonough is no longer subject to Section 16 filing requirements. Form 4 or Form 5 obligations may still apply in specific circumstances.

Explanation of responses 5 footnotes

Footnote F1

Pursuant to the terms of that certain Agreement and Plan of Merger (the "Merger Agreement"), by and among Generation Bio. Co. (the "Issuer"), XOMA Royalty Corporation ("Parent") and Parent's wholly-owned subsidiary, XRA 7 Corp. ("Merger Sub"), dated as of December 15, 2025, the shares (the "Shares") of common stock, par value $0.0001 per share, of the Issuer (the "Common Stock") that were tendered to Merger Sub prior to the expiration time of the offer were exchanged for (i) a purchase price of $4.2913 per Share to the stockholders in cash, without interest and less any applicable tax withholding (the "Cash Amount"), plus (ii) one non-tradeable contingent value right per Share (the "CVR"),

Footnote F2

(continued from footnote 1) which represents the right to receive certain contingent payments in cash in accordance with the terms and subject to the conditions of a contingent value rights agreement entered into by Parent and the rights agent, with an estimated maximum contingent consideration amount of $25.01 per CVR (the Cash Amount plus one CVR, collectively, the "Offer Price"). After completion of the tender offer, pursuant to the terms of the Merger Agreement, Merger Sub merged with and into the Issuer, effective as of February 9, 2026 (the "Effective Time"), with the Issuer continuing as the surviving corporation and a wholly owned subsidiary of Parent.

Footnote F3

The securities are directly held by the McDonough Family 2018 Irrevocable Trust, or the 2018 Trust. The reporting person is the settlor of the 2018 Trust, Allison L. McDonough and David S. Grayzel are trustees for the 2018 Trust, and the 2018 Trust is for the benefit of Graeme and Owen McDonough.

Footnote F4

The securities are directly held by the McDonough Family 2020 Irrevocable Trust, or the 2020 Trust. The reporting person is the settlor of the 2020 Trust, Allison L. McDonough and David S. Grayzel are trustees for the 2020 Trust, and the 2020 Trust is for the benefit of Allison, Graeme and Owen McDonough.

Footnote F5

Pursuant to the terms of the Merger Agreement, effective as of immediately prior to the Effective Time, each option to purchase shares of Common Stock that was outstanding and unexercised as of immediately prior to the Effective Time and had an exercise price per Share that was equal to or greater than the Cash Amount was automatically cancelled for no consideration.