X0407 4 2023-03-16 0 0001658551 Amylyx Pharmaceuticals, Inc. AMLX 0001235598 FRATES JAMES M C/O AMYLYX PHARMACEUTICALS, INC. 43 THORNDIKE STREET CAMBRIDGE MA 02141 0 1 0 0 Chief Financial Officer 0 Common Stock 2023-03-16 4 S 0 30796 31.8593 D 3213 D Common Stock 2023-03-16 4 S 0 1704 32.4649 D 1509 D Common Stock 2023-03-16 4 A 0 21667 0.00 A 23176 D Stock Option (right to buy) 32.08 2023-03-16 4 A 0 97500 0.00 A 2033-03-16 Common Stock 97500 97500 D These sales were effected by the Reporting Person pursuant to a Rule 10b5-1 trading plan adopted on November 15, 2022. The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $31.33 to $32.30. Full information regarding the number of shares sold at each separate price can be furnished to the SEC staff upon request. The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $32.33 to $32.93. Full information regarding the number of shares sold at each separate price can be furnished to the SEC staff upon request. The reported transaction involves the Reporting Person's receipt of a restricted stock unit award (a "RSU"). The RSU shall vest in 4 equal annual installments, with the first installment vesting on the first day of the month of the one year anniversary of the date of grant, subject to the Reporting Person's continued service to the Issuer through such vesting date. 1/4 of the shares subject to the option shall vest and become exercisable on the first day of the month of the one year anniversary of the date of grant, and the remaining shares shall vest monthly over the remaining 36 months, subject to the Reporting Person's continuous service to the Issuer through such vesting date. /s/ Joshua B. Cohen, as Attorney in Fact 2023-03-20