X0609 4 2026-08-18 0001658551 Amylyx Pharmaceuticals, Inc. AMLX 0001913765 Mazzariello Gina false C/O AMYLYX PHARMACEUTICALS, INC. 55 CAMBRIDGE PARKWAY, SUITE 6W CAMBRIDGE MA 02142 false true false false Chief Legal Officer false Common Stock 2026-08-18 4 A false 21284 0 A 200374 D The reported shares are represented by performance share units, or PSUs, and were awarded upon the achievement of certain performance metrics. Shares subject to the PSU vested on August 18, 2026. /s/ Joshua B. Cohen, as Attorney in Fact 2026-08-20