X0306 4 2022-01-11 0 0001827087 Vigil Neuroscience, Inc. VIGL 0001855502 Vida Ventures GP III, L.L.C. 40 BROAD STREET, SUITE 201 BOSTON MA 02109 0 0 1 0 0001855504 Vida Ventures III, L.P. 40 BROAD STREET, SUITE 201 BOSTON MA 02109 0 0 1 0 0001855503 Vida Ventures III-A, L.P. 40 BROAD STREET, SUITE 201 BOSTON MA 02109 0 0 1 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 Vida III. Vida III GP disclaims beneficial ownership of the securities held of record by Vida III, and this report shall not be deemed an admission that they are the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their 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 Vida III-A. Vida III GP disclaims beneficial ownership of the securities held of record by Vida III-A, and this report shall not be deemed an admission that they are the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their 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. VIDA VENTURES GP III, L.L.C., By: /s/ Stefan Vitorovic, its Managing Member 2022-01-11 VIDA VENTURES III, L.P., By: Vida Ventures GP III, L.L.C., its general partner, By: /s/ Stefan Vitorovic, its Managing Member 2022-01-11 VIDA VENTURES III-A, L.P., By: Vida Ventures GP III, L.L.C., its general partner, By: /s/ Stefan Vitorovic, its Managing Member 2022-01-11