ABOSNasdaqBiological Products, (No Diagnostic Substances)Fiscal year ends December 31
Acumen Pharmaceuticals, Inc.
Financials through Q2 FY2026, quarter ended Jun 30, 2026Last filing: 10-Q on Aug 12, 2026
$1.77+0.08 (+4.73%)
Close on Oct 19, 2026
- Market cap
- $127.88M
- P/E (TTM)
- –
- Dividend yield
- –
Ownership
Institutional holdings as of Jun 30, 2026, from 13F filings
Held by institutions
66.2%
48M of 72M shares
Institutional holders
96
30 new, 17 sold out
Net institutional buying
2M
In Q2 2026
Insider trades, 12 months
0 buys · 48 sales
Net sold $625.71K
Shares held by institutions
Holders of more than 5%
Latest Schedule 13D (active) or 13G (passive) filed by each holder
| Holder | Shares | % of class | Filing | As of |
|---|---|---|---|---|
| James B. Murray Jr. | 3,611,360 | 5.00% | 13G (passive) | Apr 4, 2025 |
| Sands Capital Alternatives, LLC | 3,417,075 | 5.60% | 13G (passive) amendment | Jun 30, 2025 |
| RA Capital Management, L.P. | 21,101,669 | 29.50% | 13D (active) amendment | Mar 13, 2026 |
Top institutional holders
13F holdings as of Jun 30, 2026
| Holder | Shares | % of ABOS | Value | Change | % of portfolio |
|---|---|---|---|---|---|
| Ra Capital Management, L.P. | 20,992,669 | 29.03% | $56.05M | – | 0.49% |
| Sands Capital Ventures, LLC | 3,720,105 | 5.14% | $9.93M | – | 1.62% |
| BlackRock, Inc. | 2,490,115 | 3.44% | $6.65M | +2,311,789 | 0.00% |
| Alyeska Investment Group, L.P. | 2,454,754 | 3.39% | $6.55M | – | 0.02% |
| Franklin Resources Inc | 2,305,096 | 3.19% | $6.15M | – | 0.00% |
| ADAR1 Capital Management, LLC | 2,111,334 | 2.92% | $5.64M | −45,000 | 0.26% |
| Vanguard Capital Management LLC | 1,672,072 | 2.31% | $4.46M | +165,795 | 0.00% |
| Knollwood Investment Advisory, LLC | 1,628,510 | 2.25% | $4.35M | – | 0.39% |
| Geode Capital Management, LLC | 1,141,858 | 1.58% | $3.05M | +725,620 | 0.00% |
| Ikarian Capital, LLC | 1,053,797 | 1.46% | $2.81M | – | 0.30% |
| Hudson Bay Capital Management LP | 955,000 | 1.32% | $2.55M | −13,940 | 0.01% |
| Pathstone Holdings, LLC | 859,110 | 1.19% | $2.29M | – | 0.01% |
| Renaissance Technologies LLC | 675,025 | 0.93% | $1.80M | +201,079 | 0.00% |
| Two Sigma Investments, LP | 622,882 | 0.86% | $1.66M | +92,070 | 0.00% |
| State Street Corp | 600,528 | 0.83% | $1.60M | +448,800 | 0.00% |
| Northern Trust Corp | 360,744 | 0.50% | $963.19K | +285,532 | 0.00% |
| Vanguard Portfolio Management LLC | 320,795 | 0.44% | $856.52K | New | 0.00% |
| Dimensional Fund Advisors LP | 291,559 | 0.40% | $778.97K | +171,803 | 0.00% |
| Vanguard Fiduciary Trust Co | 291,240 | 0.40% | $777.61K | +92,014 | 0.00% |
| Bank Of America Corp /De/ | 274,781 | 0.38% | $733.67K | −45,435 | 0.00% |
Institutional buying and selling by quarter
Positions opened, added to, reduced and closed by 13F filers
| Quarter | Holders | Shares held | % of shares | New / added | Reduced / closed | Shares bought | Shares sold |
|---|---|---|---|---|---|---|---|
| Q2 2026 | 96 | 48M | 66.2% | 30 / 21 | 15 / 17 | 6M | 4M |
| Q1 2026 | 84 | 46M | 63.6% | 21 / 31 | 12 / 7 | 14M | 2M |
| Q4 2025 | 71 | 36M | 49.3% | 12 / 13 | 22 / 8 | 1M | 1M |
| Q3 2025 | 69 | 36M | 49.4% | 13 / 8 | 28 / 15 | 2M | 4M |
| Q2 2025 | 71 | 38M | 52.0% | 17 / 15 | 22 / 27 | 3M | 5M |
| Q1 2025 | 81 | 40M | 55.7% | 11 / 15 | 33 / 9 | 1M | 3M |
| Q4 2024 | 80 | 43M | 58.8% | 16 / 28 | 19 / 8 | 2M | 3M |
| Q3 2024 | 73 | 44M | 60.4% | 11 / 24 | 21 / 17 | 4M | 1M |
| Q2 2024 | 81 | 44M | 60.3% | 23 / 21 | 20 / 22 | 5M | 5M |
| Q1 2024 | 80 | 44M | 60.2% | 24 / 22 | 24 / 11 | 7M | 1M |
| Q4 2023 | 67 | 38M | 53.2% | 20 / 27 | 10 / 18 | 4M | 9M |
| Q3 2023 | 66 | 44M | 60.4% | 25 / 23 | 11 / 12 | 20M | 2M |
Top mutual fund and ETF holders
Latest monthly portfolio reports (Form N-PORT)
| Fund | Shares | % of ABOS | Value | % of fund | As of |
|---|---|---|---|---|---|
| Vanguard Total Stock Market Index Fund | 1,118,322 | 1.55% | $2.99M | 0.00% | Jun 30, 2026 |
| iShares Russell 2000 ETF | 1,036,119 | 1.43% | $2.77M | 0.00% | Jun 30, 2026 |
| Franklin Biotechnology Discovery Fund | 826,400 | 1.14% | $1.78M | 0.15% | Jul 31, 2026 |
| Fidelity Small Cap Index Fund | 513,773 | 0.71% | $1.10M | 0.00% | Jul 31, 2026 |
| Vanguard Extended Market Index Fund | 513,511 | 0.71% | $1.37M | 0.00% | Jun 30, 2026 |
| iShares Russell 2000 Value ETF | 430,091 | 0.59% | $1.15M | 0.01% | Jun 30, 2026 |
| Fidelity Extended Market Index Fund | 177,191 | 0.25% | $460.70K | 0.00% | May 31, 2026 |
| iShares Micro-Cap ETF | 158,629 | 0.22% | $423.54K | 0.03% | Jun 30, 2026 |
| Schwab Small-Cap Index Fund | 115,088 | 0.16% | $247.44K | 0.00% | Jul 31, 2026 |
| Dimensional U.S. Small Cap ETF | 100,013 | 0.14% | $215.03K | 0.00% | Jul 31, 2026 |
| Master Small Cap Index Series | 88,342 | 0.12% | $235.87K | 0.00% | Jun 30, 2026 |
| Ultra-Small Company Market Fund | 87,871 | 0.12% | $234.62K | 0.16% | Jun 30, 2026 |
| Ultra-Small Company Fund | 75,000 | 0.10% | $200.25K | 0.20% | Jun 30, 2026 |
| Fidelity Small Cap Value Index Fund | 65,832 | 0.09% | $175.77K | 0.01% | Jun 30, 2026 |
| Nuveen Small Cap Blend Index Fund | 63,355 | 0.09% | $136.21K | 0.00% | Jul 31, 2026 |
Officers, directors and major owners
People who filed Forms 3, 4 or 5 in the last two years
| Name | Role | Shares owned | % of shares | Latest filing |
|---|---|---|---|---|
| Daniel Joseph OConnell | Chief Executive Officer, Director | 881,275 | 1.22% | Jan 23, 2026 |
| Derek M. Meisner | Chief Legal Officer & Corp Sec | 173,999 | 0.24% | Mar 10, 2026 |
| Eric Siemers | Chief Medical Officer | 255,371 | 0.35% | Jan 23, 2026 |
| Russell Barton | Chief Operating Officer | 205,092 | 0.28% | Jan 23, 2026 |
| Matt Zuga | CFO & Chief Business Officer | 304,924 | 0.42% | Jan 23, 2026 |
| James J. Doherty | President and CDO | 220,900 | 0.31% | Jan 21, 2026 |
| Amy Schacterle | Chief Regulatory Officer | 92,303 | 0.13% | Jan 21, 2026 |
| Derrell Porter | Director | 48,540 | 0.07% | Jun 17, 2026 |
| Nathan B. Fountain | Director | 48,150 | 0.07% | Jun 10, 2026 |
| Kimberlee C. Drapkin | Director | 48,300 | 0.07% | Jun 5, 2026 |
| John A. Stalfort III | Director | 352,219 | 0.49% | Jun 5, 2026 |
| Rajeev M. Shah | Director, 10% owner | 19,103,785 | 26.42% | Jun 5, 2026 |
| Peter Kolchinsky | Director, 10% owner | – | – | Jun 5, 2026 |
| Ra Capital Management, L.P. | Director, 10% owner | 13,043,179 | 18.04% | Jun 5, 2026 |
| RA Capital Nexus Fund II, L.P. | Director | 48,300 | 0.07% | Jun 5, 2026 |
| Laura Stoppel | Director | 48,300 | 0.07% | Jun 5, 2026 |
| George Golumbeski | Director | 35,500 | 0.05% | Jun 5, 2026 |
| Jeffrey L. Ives | Director | 48,300 | 0.07% | Jun 5, 2026 |
| Capital Healthcare Fund LP RA | Director, 10% owner | 12,800 | 0.02% | Jun 5, 2026 |
Insider trades
Common stock transactions reported on Form 4, newest first
| Insider | Date | Transaction | Shares | Price | Value | Shares after |
|---|---|---|---|---|---|---|
| Derrell Porter Director | Jun 17, 2026 | Option exercise | +13,040 | $1.07 | $13.95K | 48,540 |
| Derrell Porter Director | Jun 17, 2026 | Sale | −13,040 | $2.33 | $30.38K | 35,500 |
| Derrell Porter Director | Jun 16, 2026 | Sale | −12,800 | $2.33 | $29.82K | 35,500 |
| Derrell Porter Director | Jun 15, 2026 | Sale | −6,460 | $2.35 | $15.18K | 48,300 |
| Derrell Porter Director | Jun 15, 2026 | Option exercise | +6,460 | $1.07 | $6.91K | 54,760 |
| Nathan B. Fountain Director | Jun 9, 2026 | Sale | −6,400 | $2.23 | $14.27K | 48,150 |
| Jeffrey L. Ives Director | Jun 3, 2026 | Award | +35,500 | – | – | 48,300 |
| Nathan B. Fountain Director | Jun 3, 2026 | Award | +35,500 | – | – | 54,550 |
| John A. Stalfort III Director | Jun 3, 2026 | Award | +35,500 | – | – | 220,624 |
| RA Capital Nexus Fund II, L.P. Director | Jun 3, 2026 | Award | +35,500 | – | – | 48,300 |
| Laura Stoppel Director | Jun 3, 2026 | Award | +35,500 | – | – | 48,300 |
| Derrell Porter Director | Jun 3, 2026 | Award | +35,500 | – | – | 48,300 |
| George Golumbeski Director | Jun 3, 2026 | Award | +35,500 | – | – | 35,500 |
| Kimberlee C. Drapkin Director | Jun 3, 2026 | Award | +35,500 | – | – | 48,300 |
| Rajeev M. Shah Director, 10% owner | Mar 16, 2026 | Award | +6,060,606 | $3.30 | $20.00M | 19,103,785 |
| Derek M. Meisner Chief Legal Officer & Corp Sec | Mar 6, 2026 | Sale(10b5-1 plan) | −2,090 | $3.26 | $6.81K | 173,999 |
| Derek M. Meisner Chief Legal Officer & Corp Sec | Mar 6, 2026 | Option exercise | +2,090 | $1.85 | $3.87K | 176,089 |
| Derek M. Meisner Chief Legal Officer & Corp Sec | Feb 27, 2026 | Sale(10b5-1 plan) | −9,406 | $3.01 | $28.31K | 173,999 |
| Derek M. Meisner Chief Legal Officer & Corp Sec | Feb 27, 2026 | Option exercise | +9,406 | $1.85 | $17.40K | 183,405 |
| Derek M. Meisner Chief Legal Officer & Corp Sec | Jan 28, 2026 | Sale(10b5-1 plan) | −2,671 | $3.00 | $8.01K | 173,999 |
| Derek M. Meisner Chief Legal Officer & Corp Sec | Jan 28, 2026 | Option exercise | +2,671 | $1.85 | $4.94K | 176,670 |
| Derek M. Meisner Chief Legal Officer & Corp Sec | Jan 26, 2026 | Option exercise | +15,085 | $1.85 | $27.91K | 189,084 |
| Derek M. Meisner Chief Legal Officer & Corp Sec | Jan 26, 2026 | Sale(10b5-1 plan) | −15,085 | $3.00 | $45.26K | 173,999 |
| Derek M. Meisner Chief Legal Officer & Corp Sec | Jan 23, 2026 | Sale(10b5-1 plan) | −5,633 | $1.90 | $10.70K | 173,999 |
| Eric Siemers Chief Medical Officer | Jan 22, 2026 | Sale(10b5-1 plan) | −895 | $1.82 | $1.63K | 255,371 |
| Derek M. Meisner Chief Legal Officer & Corp Sec | Jan 22, 2026 | Sale(10b5-1 plan) | −1,054 | $1.84 | $1.94K | 179,632 |
| Matt Zuga CFO & Chief Business Officer | Jan 22, 2026 | Sale(10b5-1 plan) | −1,687 | $1.86 | $3.14K | 304,924 |
| Daniel Joseph OConnell Chief Executive Officer, Director | Jan 22, 2026 | Sale(10b5-1 plan) | −2,689 | $1.88 | $5.06K | 881,275 |
| Russell Barton Chief Operating Officer | Jan 22, 2026 | Sale(10b5-1 plan) | −462 | $1.84 | $850 | 205,092 |
| Eric Siemers Chief Medical Officer | Jan 21, 2026 | Sale(10b5-1 plan) | −2,331 | $1.80 | $4.20K | 256,266 |
| Derek M. Meisner Chief Legal Officer & Corp Sec | Jan 21, 2026 | Sale(10b5-1 plan) | −2,247 | $1.81 | $4.07K | 180,686 |
| Matt Zuga CFO & Chief Business Officer | Jan 21, 2026 | Sale(10b5-1 plan) | −2,473 | $1.81 | $4.48K | 306,611 |
| Daniel Joseph OConnell Chief Executive Officer, Director | Jan 21, 2026 | Sale(10b5-1 plan) | −9,346 | $1.81 | $16.92K | 883,964 |
| Russell Barton Chief Operating Officer | Jan 21, 2026 | Sale(10b5-1 plan) | −2,315 | $1.81 | $4.19K | 205,554 |
| Daniel Joseph OConnell Chief Executive Officer, Director | Jan 20, 2026 | Award | +299,800 | – | – | 893,310 |
| James J. Doherty President and CDO | Jan 16, 2026 | Award | +166,867 | – | – | 220,900 |
| Russell Barton Chief Operating Officer | Jan 16, 2026 | Award | +84,600 | – | – | 207,869 |
| Amy Schacterle Chief Regulatory Officer | Jan 16, 2026 | Award | +84,600 | – | – | 92,303 |
| Eric Siemers Chief Medical Officer | Jan 16, 2026 | Award | +99,133 | – | – | 258,597 |
| Derek M. Meisner Chief Legal Officer & Corp Sec | Jan 16, 2026 | Award | +99,133 | – | – | 182,933 |
| Matt Zuga CFO & Chief Business Officer | Jan 16, 2026 | Award | +99,133 | – | – | 309,084 |
| Daniel Joseph OConnell Chief Executive Officer, Director | Jan 12, 2026 | Sale(10b5-1 plan) | −5,388 | $1.73 | $9.32K | 593,510 |
| Derek M. Meisner Chief Legal Officer & Corp Sec | Jan 12, 2026 | Sale(10b5-1 plan) | −8,548 | $1.71 | $14.62K | 83,800 |
| Daniel Joseph OConnell Chief Executive Officer, Director | Jan 9, 2026 | Sale(10b5-1 plan) | −12,941 | $1.76 | $22.78K | 598,898 |
| Derek M. Meisner Chief Legal Officer & Corp Sec | Jan 9, 2026 | Sale(10b5-1 plan) | −5,200 | $1.76 | $9.15K | 92,348 |
| Daniel Joseph OConnell Chief Executive Officer, Director | Jan 8, 2026 | Sale(10b5-1 plan) | −8,143 | $1.82 | $14.82K | 611,839 |
| Russell Barton Chief Operating Officer | Jan 8, 2026 | Sale(10b5-1 plan) | −3,530 | $1.86 | $6.57K | 123,269 |
| Matt Zuga CFO & Chief Business Officer | Jan 8, 2026 | Sale(10b5-1 plan) | −6,888 | $1.82 | $12.54K | 209,951 |
| Derek M. Meisner Chief Legal Officer & Corp Sec | Jan 8, 2026 | Sale(10b5-1 plan) | −6,819 | $1.82 | $12.41K | 127,640 |
| Derek M. Meisner Chief Legal Officer & Corp Sec | Jan 8, 2026 | Sale(10b5-1 plan) | −30,092 | $1.82 | $54.77K | 97,548 |
| James J. Doherty President and CDO | Jan 8, 2026 | Sale(10b5-1 plan) | −6,467 | $1.82 | $11.77K | 54,033 |
| James J. Doherty President and CDO | Jan 7, 2026 | Sale(10b5-1 plan) | −1,700 | $1.99 | $3.38K | 60,500 |
| Amy Schacterle Chief Regulatory Officer | Jan 7, 2026 | Sale(10b5-1 plan) | −1,097 | $1.98 | $2.17K | 7,703 |
| Daniel Joseph OConnell Chief Executive Officer, Director | Jan 7, 2026 | Sale(10b5-1 plan) | −37,755 | $1.99 | $75.13K | 619,982 |
| Matt Zuga CFO & Chief Business Officer | Jan 7, 2026 | Sale(10b5-1 plan) | −1,700 | $1.99 | $3.38K | 216,839 |
| Matt Zuga CFO & Chief Business Officer | Jan 7, 2026 | Sale(10b5-1 plan) | −4,105 | $2.00 | $8.21K | 218,539 |
| Derek M. Meisner Chief Legal Officer & Corp Sec | Jan 7, 2026 | Sale(10b5-1 plan) | −1,700 | $1.99 | $3.38K | 144,529 |
| Derek M. Meisner Chief Legal Officer & Corp Sec | Jan 7, 2026 | Sale(10b5-1 plan) | −10,070 | $1.99 | $20.04K | 134,459 |
| Russell Barton Chief Operating Officer | Jan 7, 2026 | Sale(10b5-1 plan) | −1,700 | $1.99 | $3.38K | 126,799 |
| Daniel Joseph OConnell Chief Executive Officer, Director | Jan 6, 2026 | Sale(10b5-1 plan) | −5,102 | $1.97 | $10.05K | 657,737 |
Awards, option exercises, tax withholding and gifts are shown alongside open-market buys and sales. Each name links to the filing on SEC EDGAR.
Planned insider sales
Notices of proposed sale filed on Form 144 before shares are sold
| Seller | Filed | Shares | Market value | Planned sale | Acquired through |
|---|---|---|---|---|---|
| Porter Derrell Director | Jun 17, 2026 | 13,040 | $30.32K | Jun 17, 2026 | Stock Option Exercise |
| Porter Derrell Director | Jun 16, 2026 | 12,800 | $29.77K | Jun 16, 2026 | Restricted Stock |
| Porter Derrell Director | Jun 15, 2026 | 6,460 | $15.15K | Jun 15, 2026 | Stock Option Exercise |
| Fountain Nathan Director | Jun 9, 2026 | 6,400 | $14.27K | Jun 9, 2026 | Restricted Stock |
| Derek M. Meisner Officer | Mar 6, 2026 | 2,090 | $6.73K | Mar 6, 2026 | Exercise of employee stock options |
| Derek M. Meisner Officer | Feb 27, 2026 | 9,406 | $28.31K | Feb 27, 2026 | Exercise of employee stock options |
| Derek M. Meisner Officer | Jan 28, 2026 | 2,671 | $8.02K | Jan 28, 2026 | Exercise of employee stock options |
| Derek M. Meisner Officer | Jan 26, 2026 | 15,085 | $45.26K | Jan 27, 2026 | Exercise of employee stock options |
| Derek M. Meisner Officer | Jan 23, 2026 | 5,633 | $10.49K | Jan 23, 2026 | Vesting of restricted stock unit award |
| Daniel Joseph OConnell Officer, Director | Jan 22, 2026 | 2,689 | $5.07K | Jan 22, 2026 | Vesting of restricted stock unit award |
| Eric Siemers Officer | Jan 22, 2026 | 895 | $1.63K | Jan 22, 2026 | Vesting of restricted stock unit award |
| Russell Barton Officer | Jan 22, 2026 | 462 | $850 | Jan 22, 2026 | Vesting of restricted stock unit award |
| Derek M. Meisner Officer | Jan 22, 2026 | 1,054 | $1.94K | Jan 22, 2026 | Vesting of restricted stock unit award |
| Matt Zuga Officer | Jan 22, 2026 | 1,687 | $3.14K | Jan 22, 2026 | Vesting of restricted stock unit award |
| Derek M. Meisner Officer | Jan 21, 2026 | 2,247 | $4.06K | Jan 21, 2026 | Vesting of restricted stock unit award |