[Form 4] Generation Bio Co. Insider Trading Activity

Rhea-AI Filing Summary

Generation Bio Co.'s interim CEO and President, Yalonda Howze, reported equity award activity tied to a merger-related vesting event. On February 2, 2026, 1,673 restricted stock units vested and were converted into the same number of common shares at an exercise price of $0.

To cover tax withholding on this vesting, 495 common shares were withheld at a price of $5.64 per share, reducing her directly held common stock to 3,759 shares. The filing notes these RSUs came from a 53,550-unit grant made on April 5, 2023, and that under a December 15, 2025 merger agreement with XOMA Royalty Corporation and its subsidiary, all outstanding and unvested company RSUs became fully vested on February 2, 2026.

Insider Trade Summary

1,673 shares exercised/converted

Mixed 3 txns

Insider Howze Yalonda

Role INTERIM CEO & PRESIDENT

Type	Security	Shares	Price	Value
Exercise	Restricted Stock Units	1,673	$0.00	--
Exercise	Common Stock	1,673	$0.00	--
Tax Withholding	Common Stock	495	$5.64	$3K

Holdings After Transaction: Restricted Stock Units — 0 shares (Direct); Common Stock — 4,254 shares (Direct)

Footnotes (1)

1. 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.

Form 4 Insider Transactions: What Each Field Means →

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
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hours per response:			0.5

Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Howze Yalonda

(Last) (First) (Middle)

C/O GENERATION BIO CO.

301 BINNEY STREET, SUITE 401

(Street)

CAMBRIDGE MA 02142

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
Generation Bio Co. [ GBIO ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	INTERIM CEO & PRESIDENT

3. Date of Earliest Transaction (Month/Day/Year)
02/02/2026

4. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	02/02/2026		M		1,673	A	(1)	4,254	D
Common Stock	02/02/2026		F		495	D	$5.64	3,759	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Restricted Stock Units	(1)	02/02/2026		M			1,673	(2)	(2)	Common Stock	1,673	$0	0	D

Explanation of Responses:

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

2. 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.

	/s/ Shawna-Gay White, Attorney-in-Fact	02/04/2026
	** Signature of Reporting Person	Date
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