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 September 30, 2026, our officers and directors took the following actions with respect to Rule 10b5-1 trading plans:

On September 29, 2026, Eric Siemers, our Chief Medical Officer, entered into a Rule 10b5-1 trading plan that provides that Mr. Siemers, 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. Siemers as equity incentive compensation, which sales may occur from January 19, 2027 to December 31, 2029.

On September 29, 2026, Russell Barton, our Chief Operating Officer, entered into a Rule 10b5-1 trading plan that provides that Mr. Barton, 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 Mr. Barton as equity incentive compensation, which sales may occur from January 19, 2027 to December 31, 2029. On September 29, 2026, Mr. Barton also entered into a separate Rule 10b5-1 trading plan that provides that Mr. Barton, acting through a broker, may sell 331,859 shares of our common stock received upon the exercise of option awards granted to Mr. Barton as equity incentive compensation, which sales may occur from January 4, 2027 to December 31, 2027.

On September 30, 2026, James Doherty, our President and Chief Development Officer, entered into a Rule 10b5-1 trading plan that provides that Mr. Doherty, 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 166,867 RSU awards granted to Mr. Doherty as equity incentive compensation, which sales may occur from January 19, 2027 to December 31, 2029. On September 30, 2026, Mr. Doherty also entered into a separate Rule 10b5-1 trading plan that provides that Mr. Doherty, acting through a broker, may sell (1)5,000 shares of our common stock and (2)200,000 shares of our common stock received upon the exercise of option awards granted to Mr. Doherty as equity incentive compensation, which sales may occur from February 5, 2027 to December 31, 2027.