Acumen Pharmaceuticals, Inc. (ABOS) SEC Filings, Mar-Apr 2026

Acumen Pharmaceuticals is holding a virtual 2026 annual meeting on June 3, 2026 to elect three Class II directors, ratify Ernst & Young LLP as auditor for 2026, and approve an Amended and Restated 2021 Equity Incentive Plan.

The equity plan proposal would add 10,000,000 shares of common stock to the pool, remove the automatic “evergreen” increase, and explicitly prohibit repricing of stock options or stock appreciation rights without stockholder approval, other than in certain corporate transactions. As of April 8, 2026, 72,227,580 common shares were outstanding and entitled to vote.

Acumen Pharmaceuticals, Inc. Schedule 13G reports that James B. Murray Jr. beneficially owned 3,611,360 shares of common stock as of April 6, 2026, representing 5.00% of outstanding common stock based on a 72,212,758 share denominator. The filing breaks ownership into 3,468,465 shares held in Mr. Murray's revocable trust and 142,895 shares held by Praxis Technologies LLC; Mr. Murray is a manager of Praxis and shares voting/dispositive power for those shares.

Acumen Pharmaceuticals, Inc. is registering 10,833,331 shares of Common Stock for resale by selling stockholders that acquired the shares in a March 16, 2026 private placement. The prospectus states the company will not receive proceeds from these resales and that the selling stockholders will determine timing, price and method of disposition.

The prospectus notes 72,212,758 shares outstanding as of March 20, 2026 and discloses a March 31, 2026 last reported sale price of $2.36 per share. The registration is part of an S-3 shelf process and includes customary plan-of-distribution provisions and registration-rights obligations.

Acumen Pharmaceuticals, Inc. is registering the resale of up to 10,833,331 shares of its common stock.

This prospectus covers shares issued in a Private Placement completed on March 16, 2026 at $3.30 per share; the Company will not receive proceeds from resales. The Registration Rights Agreement commits the Company to keep the registration statement effective until the selling stockholders have resold the registrable securities or they can be resold under Rule 144.

Context: shares outstanding were 72,212,758 as of March 20, 2026, the Company’s common stock trades on Nasdaq Global Select (symbol ABOS), and the last reported sale price was $2.63 on March 25, 2026. The prospectus lists the selling stockholders and the permitted distribution methods; the Company will bear registration expenses.

Acumen Pharmaceuticals is a clinical-stage biopharma company focused on Alzheimer’s disease. Its lead and only clinical product candidate, sabirnetug (ACU193), is an Aβ oligomer–selective monoclonal antibody in the Phase 2 ALTITUDE-AD trial in early Alzheimer’s, with topline results expected in late 2026.

Phase 1 INTERCEPT-AD in early Alzheimer’s patients met primary and secondary objectives, showing dose-related amyloid plaque reduction, near-maximal target engagement at higher doses and an overall ARIA-E rate of 10.4%. The company is also advancing subcutaneous sabirnetug and a blood-brain barrier–penetrating EBD™ program, and has collaborations with Halozyme, JCR and Lonza. Acumen discloses substantial funding needs and an auditor “going concern” explanatory paragraph, and highlights heavy dependence on sabirnetug amid intense competition in Alzheimer’s therapies.

Acumen Pharmaceuticals reported a larger full-year 2025 net loss while funding late-stage Alzheimer’s programs. For the year ended December 31, 2025, the company recorded a net loss of $121.3 million, compared with $102.3 million in 2024, driven mainly by higher research and development spending.

R&D expenses rose to $104.9 million from $93.8 million, reflecting manufacturing, clinical and Enhanced Brain Delivery (EBD™) research costs, while G&A expenses declined slightly to $18.9 million. Cash, cash equivalents and marketable securities totaled $116.9 million as of December 31, 2025, which management expects to fund current clinical and operational activities into early 2027. A $35.75 million private placement in March 2026 further supports development.

The company’s lead antibody sabirnetug (ACU193) is being tested in the Phase 2 ALTITUDE-AD trial in early Alzheimer’s disease, with topline results expected in late 2026. Acumen is also advancing an EBD program that showed markedly higher brain exposure in non-human primates, with an IND filing for a lead clinical candidate targeted for mid-2027.

Acumen Pharmaceuticals, Inc. reported that investment entities associated with RA Capital Management, L.P. acquired 6,060,606 shares of common stock at $3.30 per share in a grant or award transaction on March 16, 2026. The shares are held indirectly, including by RA Capital Healthcare Fund, L.P., with 19,103,785 shares reported as held following the transaction. Additional indirect holdings include 1,300,034 shares held by RA Capital Nexus Fund II, L.P. and 588,850 shares held in a separately managed account. The Adviser entities and managing members disclaim beneficial ownership beyond their respective pecuniary interests.

RA Capital Management and affiliates filed Amendment No. 4 to their Schedule 13D on Acumen Pharmaceuticals. They report beneficial ownership of 21,101,669 shares of common stock, or 29.5% of the company, including 19,103,785 shares held by RA Capital Healthcare Fund.

The filing reflects a March 2026 private placement in which Acumen sold 10,833,331 shares at $3.30 per share. RA Capital Healthcare Fund purchased 6,060,606 of those shares for total consideration of $19,999,999.80. Acumen agreed to register these PIPE shares for resale under a registration rights agreement.