Form 4 Filing for Amylyx Pharmaceuticals, Inc.

This filing details stock transactions by James M. Frates, the Chief Financial Officer of Amylyx Pharmaceuticals, Inc. On September 10, 2026, Mr. Frates disposed of 9,768 shares of Common Stock at a weighted average price of $32.27 and 1,042 shares of Common Stock at a weighted average price of $33.23. These sales were primarily to cover tax withholding obligations related to the vesting of performance stock units, as indicated by footnote F1. The transactions were automatic and not at Mr. Frates' discretion. Footnotes F2 and F3 provide further detail on the weighted average prices and the range of prices for these sales. The filing also discloses shares held indirectly through various trusts, where Mr. Frates serves as trustee. These holdings include 100,000 shares in the JAMES M. FRATES 2025 GRAT NO 1 U/A DTD 12/12/2025, 15,459 shares in the James M. Frates 2024 Grantor Retained Annuity Trust No. 1, 11,072 shares in the FRATES FAMILY 2013 IRREV TRUST, and 40,000 shares in the JAMES M. FRATES 2026 GRANTOR RETAINED ANNUITY TRUST NO. 1. Mr. Frates disclaims beneficial ownership of these trust shares except to the extent of his pecuniary interest.