144 0001685994 XXXXXXXX LIVE 0001707502 Solid Biosciences Inc. 001-38360 500 Rutherford Avenue Charlestown MA 02129 (617)-337-4680 Cumbo Alexander Officer Director Common Stock ETRADE FINANCIAL CORPORATION

3 EDISON DRIVE ALPHARETTA GA 30005

10808 55228.88 77996546 12/03/2025 NASDAQ Common Stock 12/02/2025 Settlement of vested restricted stock units Issuer N 10808 12/02/2025 Compensation Y The sale reported on this Form 144 was made to cover witholding taxes following the vesting of previously granted restricted stock units pursuant to a durable sale instruction letter adopted by Mr. Cumbo on August 18, 2024 effecting the sell-cover-election. The sale does not represent a discretionary trade by Mr. Cumbo. 12/03/2025 08/18/2024 /s/ Kimberly Cornwell as attorney-in-fact for Alexander Cumbo