Acumen Pharmaceuticals, Inc.

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 March 31, 2026, our officers and directors took the following actions with respect to 10b5-1 trading plans:

On March 31, 2026, Matthew Zuga, our Chief Financial Officer and Chief Business Officer, terminated a Rule 10b5-1 trading plan that had been adopted on December 31, 2025 that provided that Mr. Zuga, acting through a broker, could sell (1) up to 83,110 shares of our common stock received upon the settlement of RSU awards granted to Mr. Zuga as equity incentive compensation, which sales were eligible to occur from April 6, 2026 to April 6, 2027; and (2)343,294 shares of our common stock received upon the exercise of option awards granted to Mr. Zuga as equity incentive compensation, which sales were eligible to occur from April 6, 2026 to April 6, 2027.

On March 31, 2026, Jeffery Ives, a member of our Board of Directors, entered into a Rule 10b5-1 trading plan that provides that Mr. Ives, acting through a broker, may sell (1) up to 12,800 shares of our common stock received upon the settlement of RSU awards granted to Mr. Ives as equity compensation, which sales may occur from June 30, 2026 to June 30, 2027; and (2)44,500 shares of our common stock received upon the exercise of option awards granted to Mr. Ives as equity compensation, which sales may occur from June 30, 2026 to June 30, 2027.

On March 31, 2026, Derek Meisner, our Chief Legal Officer, entered into a Rule 10b5-1 trading plan that provides that Mr. Meisner, 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. Meisner as equity incentive compensation, which sales may occur from January 19, 2027 to January 31, 2029. On March 31, 2026, Mr. Meisner also entered into a separate Rule 10b5-1 trading plan that provides that Mr. Meisner, acting through a broker, may sell up to (1)702,548 shares of common stock received upon the exercise of option awards granted to Mr. Meisner as equity incentive compensation, which sales may occur from October 1, 2026 through September 30, 2030; and (2)173,999 shares of common stock received upon the vesting of RSU awards granted to Mr. Meisner as equity incentive compensation, which sales may occur from January 5, 2027 to September 30, 2030.