Acumen Pharmaceuticals, Inc.

Item 7.01 Regulation FD Disclosure. On September 16, 2026, the Company will host an Investor Day beginning at 10:00 a.m. Eastern Time, which will be live-webcast. Following the conclusion of the Investor Day, the webcast and corresponding slide presentation that will be used by members of the Company’s executive team at the Investor Day will be posted on the Company’s investor relations website. In addition, a copy of this presentation is attached as Exhibit 99.1 to this Current Report on Form 8-K (this “Report”). The information in this Item 7.01 of this Report (including Exhibit 99.1), is being furnished and shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that Section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as expressly set forth by specific reference in such filing. The Company’s submission of this Report shall not be deemed an admission as to the materiality of any information required to be disclosed solely to satisfy the requirements of Regulation FD.