X0508 4 2025-10-31 1 0001733294 Generation Bio Co. GBIO 0001907682 Paone Antoinette C/O GENERATION BIO CO., 301 BINNEY ST CAMBRIDGE MA 02142 false true false false CHIEF OPERATING OFFICER 0 The reporting person will no longer serve as Generation Bio Co.'s chief operating officer effective October 31, 2025. As a result, the reporting person is no longer subject to Section 16 in connection with her transactions in the equity securities of Generation Bio Co. and therefore will no longer report any such transactions on Form 4 or Form 5. /s/ Shawna-Gay White, Attorney-in-Fact 2025-10-31