Acumen Pharmaceuticals, Inc.

Officer and Director Trading Arrangements

From time to time, our officers (as defined in Rule 16a-1(f)) and directors may enter into Rule 10b5-1 ornon-Rule 10b5-1 trading plans (as each such term is defined in Item 408 of Regulation S-K). The trading plans are intended to satisfy the affirmative defense in Rule 10b5-1(c). During the three months ended June 30, 2026, our officers and directors took the following actions with respect to 10b5-1 trading plans:

On June 29, 2026, Daniel O’Connell, our Chief Executive Officer and a member of our board of directors, entered into a Rule 10b5-1 trading plan that provides that Mr. O’Connell, acting through a broker, may sell the number of shares of common stock sufficient to cover the taxes, commissions and any fees associated with the vesting of up to 299,800 RSU awards granted to Mr. O’Connell as equity compensation, which sales may occur from January 21, 2027 to December 31, 2029. On June 30, 2026, Mr.O’Connell also entered into a separate Rule 10b5-1 trading plan that provides that Mr. O’Connell, acting through a broker, may sell (1)294,858 shares of our common stock and (2)418,903 shares of our common stock received upon the exercise of option awards granted to Mr.O’Connell as equity incentive compensation, which sales may occur from September 29, 2026 to June 30, 2027.

On June 29, 2026, Matthew Zuga, our Chief Financial Officer and Chief Business Officer, entered into a Rule 10b5-1 trading plan that provides that Mr. Zuga, acting through a broker, may sell the number of shares of common stock sufficient to cover the taxes, commissions and any fees associated with the vesting of up to 99,133 RSU awards granted to Mr. Zuga as equity incentive compensation, which sales may occur from January 19, 2027 to December 31, 2029. On June 29, 2026, Mr. Zuga also entered into a separate Rule 10b5-1 plan that provides that Mr. Zuga, acting through a broker, may sell 616,591 shares of our common stock received upon the exercise of option awards granted to Mr. Zuga as equity incentive compensation, which sales may occur from September 28, 2026 to September 28, 2027.

On June 30, 2026, Amy Schacterle, Ph.D., our Chief Regulatory Officer and Head of Quality, entered into a Rule 10b5-1 trading plan that provides that Dr. Schacterle, acting through a broker, may sell 147,500 shares of our common stock received upon the exercise of option awards and 31,133 shares of our common stock received upon the settlement of RSU awards granted to Dr. Schacterle as equity incentive compensation, which sales may occur from October 1, 2026 to December 31, 2027. On June 30, 2026, Dr. Schacterle also entered into a separate Rule 10b5-1 plan that provides that Dr. Schacterle, acting through a broker, may sell the number of shares of common stock sufficient to cover the taxes, commissions and any fees associated with the vesting of up to 84,600 RSU awards granted to Dr. Schacterle as equity incentive compensation, which sales may occur from January 19, 2027 to December 31, 2029.

Approval of Amended and Restated 2021 Plan

On June 3, 2026, the Company’s stockholders approved the adoption of the Company’s Amended and Restated 2021 Equity Incentive Plan (the “Amended and Restated 2021 Plan”) to (i) increase the number of shares available for issuance under the Company’s 2021 Equity Incentive Plan (the “2021 Plan”) by 10,000,000 shares, (ii) remove the automatic

“evergreen” share pool increase provision from the 2021 Plan, and (iii) prohibit repricing of stock options without stockholder approval (other than in connection with certain corporate transactions). This disclosure is qualified in its entirety by reference to the Amended and Restated 2021 Plan, which is filed as Exhibit 10.1 to this Form 10-Q.