Common Stock, $0.0001 par value per share

Vigil Neuroscience, Inc.

100 Forge Road, Suite 700, Watertown, MA, 02472

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.