Eric Siemers, Chief Medical Officer at Acumen Pharmaceuticals (NASDAQ: ABOS), completed stock transactions totaling 3,226 shares of the firm's common stock during January 21 and 22, 2026, netting approximately $5,832 in proceeds. These sales were made to cover tax obligations resulting from the vesting of restricted stock units (RSUs).
The transactions were executed in two tranches: on January 21, Siemers sold 2,331 shares at a weighted average price of $1.8035, with individual trade prices ranging between $1.76 and $1.87 per share. The following day, January 22, he sold an additional 895 shares at $1.82 each. Following these sales, Siemers directly retains ownership of 255,371 shares of Acumen's common stock.
All sales were conducted pursuant to a pre-established Rule 10b5-1 trading plan established on September 3, 2024, indicating that these trades were predetermined and not motivated by recent developments.
Separately, Acumen Pharmaceuticals disclosed a net loss of $26.5 million for the third quarter of 2025. Despite the financial deficit, the company has reported encouraging progress in its Alzheimer’s disease therapeutic efforts, which has positively influenced investor perception. Notably, Acumen recently initiated dosing of the first participant in the open-label extension phase of its Phase 2 ALTITUDE-AD clinical trial for its lead compound, sabirnetug. This extension will enable enrolled participants to receive sabirnetug treatment for an additional 52 weeks.
The company also shared new data at the 18th Annual Clinical Trials on Alzheimer’s Disease conference. The presentation focused on advancements in drug delivery mechanisms, aiming to enhance the administration of their treatment candidates. Furthermore, Acumen announced it would present strategies employed in recruiting participants for the Phase 2 ALTITUDE-AD study, which successfully completed its enrollment period earlier this year.
In the context of these developments, Stifel has reaffirmed its Buy rating on Acumen Pharmaceuticals, reflecting sustained confidence in the firm’s promising clinical pipeline following recent communications with company leadership.