X0306 4 2022-01-06 0 0001658551 Amylyx Pharmaceuticals, Inc. AMLX 0001543112 Morningside Venture Investments Ltd C/O THC MGMT SERVICES SAM 2ND FL LE PRIN DE GALLES, 3-5 AVE DES CITRONNIERS MONACO O9 MC 98000 MONACO 0 0 1 0 Common Stock 2022-01-11 4 C 0 10415650 A 10415650 D Common Stock 2022-01-11 4 P 0 263158 19.00 A 10678808 D Series A Preferred Stock 2022-01-11 4 C 0 1409035 0.00 D Common Stock 1409035 0 D Series B Preferred Stock 2022-01-11 4 C 0 6410964 0.00 D Common Stock 6410964 0 D Series C-1 Preferred Stock 2022-01-11 4 C 0 974107 0.00 D Common Stock 974107 0 D Series C-2 Preferred Stock 2022-01-11 4 C 0 1621544 0.00 D Common Stock 1621544 0 D Upon the closing of the Issuer's initial public offering, all shares of Series A, Series B, Series C-1 and Series C-2 Preferred Stock (the "Preferred Stock") automatically converted into the number of shares of the Issuer's Common Stock shown in column 4 of Table I without payment or further consideration. The Preferred Stock had no expiration date. Frances Anne Elizabeth Richard, Jill Marie Franklin, Peter Stuart Allenby Edwards and Cheung Ka Ho, are the directors of Morningside and share voting and dispositive power with respect to the securities held by Morningside Venture Investments Limited ("Morningside") and MVIL, LLC ("MVIL LLC"), Morningside's wholly-owned subsidiary. Cheng Yee Wing and Wong See Wai are the managers of MVIL LLC and share voting and dispositive power with respect to the securities held by MVIL LLC. Ms. Cheng and Mr. Wong each disclaim ownership of the securities owned by MVIL LLC. The shares of Series C-2 Preferred Stock and the Common Stock received upon conversion of the C-2 Preferred Stock are held by MVIL LLC. /s/ Frances Anne Elizabeth Richard, for Morningside Venture Investments Limited 2022-01-25