X0306 4 2022-01-11 0 0001827087 Vigil Neuroscience, Inc. VIGL 0001826967 Vitorovic Stefan VIGIL NEUROSCIENCE, INC. 1 BROADWAY, 7TH FLOOR, SUITE 07-300 CAMBRIDGE MA 02142 1 0 0 0 Common Stock 2022-01-11 4 C 0 3333245 A 3333245 I By Vida Ventures III, L.P. Common Stock 2022-01-11 4 C 0 7684 A 7684 I By Vida Ventures III-A, L.P. Common Stock 2022-01-11 4 P 0 1671148 14.00 A 5004393 I By Vida Ventures III, L.P. Common Stock 2022-01-11 4 P 0 3852 14.00 A 11536 I By Vida Ventures III-A, L.P. Series B Preferred Stock 2022-01-11 4 C 0 9243756 0.00 D Common Stock 3333245 0 I By Vida Ventures III, L.P. Series B Preferred Stock 2022-01-11 4 C 0 21310 0.00 D Common Stock 7684 0 I By Vida Ventures III-A, L.P. Each share of Series B Preferred Stock automatically converted into shares of the Issuer's common stock, par value $0.0001 per share ("Common Stock") on a one-for-2.7732 basis upon the closing of the Issuer's initial public offering on January 11, 2022 and had no expiration date. The shares are held directly by Vida Ventures III, L.P. ("Vida III"). Vida Ventures GP III, L.L.C. ("Vida III GP") is the general partner of of Vida III. The Reporting Person is a managing member of Vida III GP and disclaims beneficial ownership of the shares held directly by Vida III, except to the extent of his pecuniary interest therein, if any. The shares are held directly by Vida Ventures III-A, L.P. ("Vida III-A"). Vida III GP is the general partner of of Vida III-A. The Reporting Person is a managing member of Vida III GP and disclaims beneficial ownership of the shares held directly by Vida III-A, except to the extent of his pecuniary interest therein, if any. On January 11, 2022, Vida III purchased 1,671,148 shares of Common Stock of the Issuer at a price of $14.00 per share pursuant to an underwritten public offering. On January 11, 2022, Vida III-A purchased 3,852 shares of Common Stock of the Issuer at a price of $14.00 per share pursuant to an underwritten public offering. /s/Jennifer Ziolkowski, Attorney-in-Fact 2022-01-11