144 0001898314 XXXXXXXX LIVE 0001658551 Amylyx Pharmaceuticals, Inc. 001-41199 55 Cambridge Parkway Suite 6W Cambridge MA 02142 617-682-0917 Klee Justin B. Officer Director Common Morgan Stanley Smith Barney LLC

1 New York Plaza 8th Floor New York NY 10004

7715 85590 3317586 01/06/2026 NASDAQ Common 01/06/2026 Vesting of Restricted Stock Units Issuer N 18750 01/06/2026 N/A Y This sale represents shares sold solely to satisfy tax withholding obligations arising from the vesting of restricted stock units. 01/06/2026 /s/ Joshua B. Cohen, as Attorney in Fact