X0206 3 2022-01-06 0 0001827087 Vigil Neuroscience, Inc. VIGL 0001812049 Atlas Venture Fund XII, L.P. 300 TECHNOLOGY SQUARE, 8TH FLOOR CAMBRIDGE MA 02139 0 0 1 0 0001845875 Atlas Venture Associates XII, L.P. 300 TECHNOLOGY SQUARE, 8TH FLOOR CAMBRIDGE MA 02139 0 0 1 0 0001845871 Atlas Venture Associates XII, LLC 300 TECHNOLOGY SQUARE, 8TH FLOOR CAMBRIDGE MA 02139 0 0 1 0 0001759241 Atlas Venture Opportunity Fund I, L.P. 300 TECHNOLOGY SQUARE, 8TH FLOOR CAMBRIDGE MA 02139 0 0 1 0 0001780065 Atlas Venture Associates Opportunity I, L.P. 300 TECHNOLOGY SQUARE, 8TH FLOOR CAMBRIDGE MA 02139 0 0 1 0 0001780066 Atlas Venture Associates Opportunity I, LLC 300 TECHNOLOGY SQUARE, 8TH FLOOR CAMBRIDGE MA 02139 0 0 1 0 Common Stock 1442376 I By Atlas Venture Fund XII, L.P. Series A Preferred Stock Common Stock 2831520 I By Atlas Venture Fund XII, L.P. Series B Preferred Stock Common Stock 1027978 I By Atlas Venture Opportunity Fund I, L.P. These shares are held directly by Atlas Venture Fund XII, L.P. ("Atlas Venture Fund XII"). The general partner of Atlas Venture Fund XII is Atlas Venture Associates XII, L.P. ("AVA XII LP"). Atlas Venture Associates XII, LLC ("AVA XII LLC") is the general partner of AVA XII LP. Each of AVA XII LP and AVA XII LLC disclaims Section 16 beneficial ownership of the securities held by Atlas Venture Fund XII, except to the extent of its pecuniary interest therein, if any. These shares of Series A Preferred Stock and Series B Preferred Stock (collectively, the "Preferred Stock") are convertible into Common Stock on a one-for-2.7732 basis at the option of the holder, and will automatically convert into the number of shares shown in Column 3 immediately prior to the closing of the Issuer's initial public offering. The Preferred Stock has no expiration date. The shares are held directly by Atlas Venture Opportunity Fund I, L.P. ("Atlas Venture Opportunity Fund I"). The general partner of Atlas Venture Opportunity Fund I is Atlas Venture Associates Opportunity I, L.P. ("AVAO I LP"). Atlas Venture Associates Opportunity I, LLC ("AVAO I LLC") is the general partner of AVAO I LP. Each of AVAO I LP and AVAO I LLC disclaims Section 16 beneficial ownership of the securities held by Atlas Venture Opportunity Fund I, except to the extent of its pecuniary interest therein, if any. Atlas Venture Fund XII, L.P. By: Atlas Venture Associates XII, L.P., Its: General Partner By: Atlas Venture Associates XII, LLC, Its General Partner, By: /s/ Ommer Chohan 2022-01-06 Atlas Venture Associates XII, L.P., By: Atlas Venture Associates XII, LLC, Its General Partner, By: /s/ Ommer Chohan 2022-01-06 Atlas Venture Associates XII, LLC, By: /s/ Ommer Chohan 2022-01-06 Atlas Venture Opportunity Fund I, L.P., By: Atlas Venture Associates Opportunity I, L.P., its general partner, By: Atlas Venture Associates Opportunity I, LLC, its general partner, By: Ommer Chohan, Chief Financial Officer /s/ Ommer Chohan 2022-01-06 Atlas Venture Associates Opportunity I, L.P., By: Atlas Venture Associates Opportunity I, LLC, its general partner, By: Ommer Chohan, Chief Financial Officer /s/ Ommer Chohan 2022-01-06 Atlas Venture Associates Opportunity I, LLC By: Ommer Chohan, Chief Financial Officer /s/ Ommer Chohan 2022-01-06