SCHEDULE 13D/A 0001193125-22-012547 0001867472 XXXXXXXX LIVE 2 Common Stock, $0.0001 par value per share 05/22/2025 false 0001827087 92673K108 Vigil Neuroscience, Inc.

100 Forge Road, Suite 700 Watertown MA 02472

Patrick Smerkers 240-800-1200 c/o Northpond Ventures, LLC 7500 Old Georgetown Road, Suite 850 Bethesda MD 20814 0001867472 N Northpond Ventures, LP OO N DE 0.00 0.00 0.00 0.00 0.00 N 0.0 PN 0001867470 N Northpond Ventures GP, LLC OO N DE 0.00 0.00 0.00 0.00 0.00 N 0.0 OO 0001869128 N Northpond Ventures II, LP OO N DE 0.00 0.00 0.00 0.00 0.00 N 0.0 PN 0001869114 N Northpond Ventures II GP, LLC OO N DE 0.00 0.00 0.00 0.00 0.00 N 0.0 OO 0001867627 N Michael P. Rubin OO N X1 0.00 0.00 0.00 0.00 0.00 N 0.0 IN Common Stock, $0.0001 par value per share Vigil Neuroscience, Inc. 100 Forge Road, Suite 700 Watertown MA 02472 This Amendment No. 2 (this "Amendment No. 2" or this "Schedule 13D/A") amends and supplements the statement on Schedule 13D originally filed with the Securities and Exchange Commission (the "SEC") on January 19, 2022, and amended on December 16, 2022 (as amended, the "Statement") by the Reporting Persons. Unless otherwise defined herein, capitalized terms used in this Amendment No. 2 shall have the meanings ascribed to them in the Statement. Unless amended or supplemented below, the information in the Statement remains unchanged. Rows 11 and 13 of each Reporting Person's cover page to this Schedule 13D/A set forth the aggregate number of shares of common stock and percentages of the shares of common stock beneficially owned by such Reporting Person and are incorporated by reference. Rows 7 through 10 of each Reporting Person's cover page to this Schedule 13D/A set forth the number of shares of common stock as to which such Reporting Person has the sole or shared power to vote or direct the vote and sole or shared power to dispose or to direct the disposition and are incorporated by reference. Except as set forth below, none of the Reporting Persons has effected any transactions with respect to the securities of the Issuer during the past sixty days. Weighted Low High Reporting No. Average Price Price Transaction Person Date Shares Price ($) ($) ($) Open Market Sale Northpond LP 05/22/2025 2,831,520 7.89 7.82 8.08 Open Market Sale Northpond II LP 05/22/2025 1,382,978 7.89 7.82 8.08 No other person is known to have the right to receive or the power to direct the receipt of dividends from, or any proceeds from the sale of, the securities beneficially owned by any of the Reporting Persons. The Reporting Persons ceased to be the beneficial owners of more than five percent of the common stock on May 22, 2025. Northpond Ventures, LP /s/ Patrick Smerkers 05/27/2025 Northpond Ventures GP, LLC /s/ Patrick Smerkers 05/27/2025 Northpond Ventures II, LP /s/ Patrick Smerkers 05/27/2025 Northpond Ventures II GP, LLC /s/ Patrick Smerkers 05/27/2025 Michael P. Rubin /s/ Michael P. Rubin 05/27/2025