Catherine Stehman-Breen - 04 Jun 2025 Form 4 Insider Report for Generation Bio Co. (GBIO)

Role: Director
Signature: /s/ Shawna-Gay White, Attorney-in-Fact
Issuer symbol: GBIO
Transactions as of: 04 Jun 2025
Net transactions value: $0
Form type: 4
Filing time: 06 Jun 2025, 16:05:21 UTC
Previous filing: 03 Jun 2025
Next filing: 09 Feb 2026
SEC: View on sec.gov

Reporting Owners (1)

Name	Relationship	Address	Signature	Signature date	CIK
Stehman-Breen Catherine	Director	C/O GENERATION BIO CO., 301 BINNEY ST, CAMBRIDGE	/s/ Shawna-Gay White, Attorney-in-Fact	06 Jun 2025	0001702233

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	Stock Option (right to buy)	Award	$0	+30,000		$0.000000	30,000	04 Jun 2025	Common Stock	30,000	$0.3874	Direct	F1

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

Explanation of Responses:

Id	Content
F1	This option was granted on June 4, 2025. The shares underlying the option will fully vest on the earlier of: June 4, 2026 and the date of Generation Bio's 2026 annual meeting of stockholders.