Phillip Samayoa - 15 Oct 2025 Form 4 Insider Report for Generation Bio Co. (GBIO)

Role
CHIEF SCIENTIFIC OFFICER
Signature
/s/ Shawna-Gay White, Attorney-in-Fact
Issuer symbol
GBIO
Transactions as of
15 Oct 2025
Net transactions value
-$228
Form type
4
Filing time
17 Oct 2025, 16:05:16 UTC
Previous filing
17 Jul 2025
Next filing
31 Oct 2025
SEC
View on sec.gov

Reporting Owners (1)

Name Relationship Address Signature Signature date CIK
Samayoa Phillip CHIEF SCIENTIFIC OFFICER C/O GENERATION BIO CO., 301 BINNEY STREET, SUITE 401, CAMBRIDGE /s/ Shawna-Gay White, Attorney-in-Fact 17 Oct 2025 0001946316

Transactions Table

Type Sym Class Transaction Value $ Shares Change % * Price $ Shares After Date Ownership Footnotes
transaction GBIO Common Stock Options Exercise +114 +0.81% 14,172 15 Oct 2025 Direct F1, F2
transaction GBIO Common Stock Tax liability $228 -34 -0.24% $6.71 14,138 15 Oct 2025 Direct F1

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 -114 -17% $0.000000 573 15 Oct 2025 Common Stock 114 Direct F1, F2, F3
* An asterisk sign (*) next to the price indicates that the price is likely invalid.

Explanation of Responses:

Id Content
F1 Amounts reported in this Form 4 reflect the one-for-10 reverse stock split effected by the issuer on July 21, 2025.
F2 Each restricted stock unit represents the right to receive one share of the company's common stock.
F3 On January 20, 2023, the reporting person was granted 1,834 restricted stock units. The shares underlying the restricted stock units vest over four years, with 25% of the shares vested on January 15, 2024 and the remaining shares vesting in equal quarterly installments thereafter.