Yalonda Howze - 02 Feb 2026 Form 4 Insider Report for Generation Bio Co. (GBIO)

Role: INTERIM CEO & PRESIDENT
Signature: /s/ Shawna-Gay White, Attorney-in-Fact
Issuer symbol: GBIO
Transactions as of: 02 Feb 2026
Net transactions value: -$2,792
Form type: 4
Filing time: 04 Feb 2026, 16:05:25 UTC
Previous filing: 16 Jan 2026
Next filing: 09 Feb 2026
SEC: View on sec.gov

Reporting Owners (1)

Name	Relationship	Address	Signature	Signature date	CIK
Howze Yalonda	INTERIM CEO & PRESIDENT	C/O GENERATION BIO CO., 301 BINNEY STREET, SUITE 401, CAMBRIDGE	/s/ Shawna-Gay White, Attorney-in-Fact	04 Feb 2026	0001828153

Transactions Table

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Ownership	Footnotes
transaction	GBIO	Common Stock	Options Exercise		+1,673	+65%		4,254	02 Feb 2026	Direct	F1
transaction	GBIO	Common Stock	Tax liability	$2,792	-495	-12%	$5.64	3,759	02 Feb 2026	Direct

Derivative Securities (e.g., puts, calls, warrants, options, convertible securities)

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Underlying Class	Amount	Exercise Price	Ownership	Footnotes
transaction	GBIO	Restricted Stock Units	Options Exercise	$0	-1,673	-100%	$0.000000	0	02 Feb 2026	Common Stock	1,673		Direct	F1, F2

* An asterisk sign (*) next to the price indicates that the price is likely invalid.

Explanation of Responses:

Id	Content
F1	Each restricted stock unit represents the right to receive one share of the company's common stock.
F2	The grant of 53,550 restricted stock units was made on April 5, 2023. Pursuant to the terms of that certain Agreement and Plan of Merger, by and among the Issuer, XOMA Royalty Corporation ("Parent") and Parent's wholly-owned subsidiary, XRA 7 Corp., dated as of December 15, 2025 (the "Merger Agreement"), prior to the effective time of the merger as contemplated by the Merger Agreement, each restricted stock unit of the Issuer that was outstanding and unvested became vested in full on February 2, 2026.

Content

Each restricted stock unit represents the right to receive one share of the company's common stock.

The grant of 53,550 restricted stock units was made on April 5, 2023. Pursuant to the terms of that certain Agreement and Plan of Merger, by and among the Issuer, XOMA Royalty Corporation ("Parent") and Parent's wholly-owned subsidiary, XRA 7 Corp., dated as of December 15, 2025 (the "Merger Agreement"), prior to the effective time of the merger as contemplated by the Merger Agreement, each restricted stock unit of the Issuer that was outstanding and unvested became vested in full on February 2, 2026.