Matthew Stanton - 15 Jan 2023 Form 4 Insider Report for Generation Bio Co. (GBIO)

Role: CHIEF SCIENTIFIC OFFICER
Signature: /s/ Jennifer Elliott, Attorney-in-Fact
Issuer symbol: GBIO
Transactions as of: 15 Jan 2023
Net transactions value: -$13,148
Form type: 4
Filing time: 18 Jan 2023, 16:02:40 UTC
Previous filing: 18 Oct 2022
Next filing: 24 Jan 2023
SEC: View on sec.gov

Transactions Table

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Ownership	Footnotes
transaction	GBIO	Common Stock	Options Exercise		+7,438	+3.5%		221,355	15 Jan 2023	Direct	F1
transaction	GBIO	Common Stock	Tax liability	$13,148	-2,578	-1.2%	$5.10	218,777	15 Jan 2023	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	-7,438	-20%	$0.000000	29,748	15 Jan 2023	Common Stock	7,438		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	On January 21, 2022, the reporting person was granted 59,500 restricted stock units. The shares underlying the restricted stock units vest over two years, with 25% of the shares vested on July 15, 2022 and the remaining shares vesting in equal quarterly installments thereafter.