144 0001913765 XXXXXXXX LIVE 0001658551 Amylyx Pharmaceuticals, Inc. 001-41199 55 Cambridge Parkway Suite 6W Cambridge MA 02142 617-682-0917 Mazzariello Gina Officer Common Morgan Stanley Smith Barney LLC

1 New York Plaza 8th Floor New York NY 10004

6844 99379 134430 03/02/2026 NASDAQ Common 03/02/2026 Vesting of Restricted Stock Units Issuer N 20545 03/02/2026 N/A N Mazzariello Gina

55 Cambridge Parkway Suite 6W Cambridge MA 02142

Common 02/02/2026 3448 50515 Mazzariello Gina

55 Cambridge Parkway Suite 6W Cambridge MA 02142

Common 02/23/2026 3419 48352 This sale represents shares required to be sold by the Reporting Person to cover tax withholding obligations in connection with the vesting of restricted stock units. Such sales were automatic and not at the discretion of the Reporting Person. 03/02/2026 /s/ Joshua B. Cohen, as Attorney in Fact