Ranked by reported Q1 2026 13F market value
Share of total reported institutional value in ABOS held by the largest 10 / 25 filers.
| # | Institution | Shares Held | Market Value | QoQ Change | Ownership % | % of Fund |
|---|---|---|---|---|---|---|
| 1 | RA CAPITAL MANAGEMENT, L.P. | 21.0M | $49.5M | +40.6% | 34.657% | 0.52% |
| 2 | Sands Capital Alternatives, LLC | 3.7M | $8.8M | +8.9% | 6.141% | 2.08% |
| 3 | Alyeska Investment Group, L.P. | 2.5M | $5.8M | +161.3% | 4.053% | 0.02% |
| 4 | FRANKLIN RESOURCES INC | 2.3M | $5.4M | 0.0% | 3.805% | 0.00% |
| 5 | ADAR1 Capital Management, LLC | 2.2M | $5.1M | +142.0% | 3.560% | 0.32% |
| 6 | Knollwood Investment Advisory, LLC | 1.6M | $3.8M | 0.0% | 2.688% | 0.39% |
| 7 | VANGUARD CAPITAL MANAGEMENT LLC | 1.5M | $3.6M | β | 2.487% | 0.00% |
| 8 | FMR LLC | 1.2M | $2.7M | -42.9% | 1.911% | 0.00% |
| 9 | Ikarian Capital, LLC | 1.1M | $2.5M | +314.4% | 1.740% | 0.26% |
| 10 | Hudson Bay Capital Management LP | 969K | $2.3M | +33.7% | 1.600% | 0.02% |
| 11 | Pathstone Holdings, LLC | 859K | $2.0M | 0.0% | 1.418% | 0.01% |
| 12 | SUSQUEHANNA INTERNATIONAL GROUP, LLP | 713K | $1.7M | +91.1% | 1.178% | 0.00% |
| 13 | MILLENNIUM MANAGEMENT LLC | 660K | $1.6M | +12.9% | 1.089% | 0.00% |
| 14 | TWO SIGMA INVESTMENTS, LP | 531K | $1.3M | +270.6% | 0.876% | 0.00% |
| 15 | Laurion Capital Management LP | 525K | $1.2M | -39.4% | 0.868% | 0.06% |
| 16 | RENAISSANCE TECHNOLOGIES LLC | 474K | $1.1M | +12.0% | 0.782% | 0.00% |
| 17 | GEODE CAPITAL MANAGEMENT, LLC | 416K | $983K | +1.5% | 0.687% | 0.00% |
| 18 | BANK OF AMERICA CORP /DE/ | 320K | $756K | +33.3% | 0.529% | 0.00% |
| 19 | BOOTHBAY FUND MANAGEMENT, LLC | 273K | $644K | +589.7% | 0.451% | 0.02% |
| 20 | GOLDMAN SACHS GROUP INC | 207K | $488K | +75.4% | 0.341% | 0.00% |
| 21 | VANGUARD FIDUCIARY TRUST CO | 199K | $470K | β | 0.329% | 0.00% |
| 22 | MARSHALL WACE, LLP | 193K | $455K | +822.6% | 0.318% | 0.00% |
| 23 | BlackRock, Inc. | 178K | $421K | +5.2% | 0.294% | 0.00% |
| 24 | BRIDGEWAY CAPITAL MANAGEMENT, LLC | 176K | $416K | +3.5% | 0.291% | 0.01% |
| 25 | STATE STREET CORP | 152K | $358K | +51.5% | 0.251% | 0.00% |
denotes a marquee investor (Buffett, Burry, ARK, Tiger Global, Pershing Square, Baupost and other widely-followed managers). β% of Fundβ shows how much of that investorβs total 13F portfolio is invested in ABOS β a direct measure of their conviction.
Filings activity in ABOS during Q1 2026, grouped by how each filer changed its position.
Institutions that opened a new ABOS position in Q1 2026
Institutions that fully closed their ABOS position in Q1 2026
8 quarters of 13F filings Β· Ξ columns show change vs prior quarter
| Quarter | Inst. Holders | Ξ Holders | Ownership % | Ξ Ownership | Total 13F Value | Ξ Value |
|---|---|---|---|---|---|---|
| Q1 2026 | 83 | +19% | 74.18% | +23.10 pp | $106M | +45% |
| Q4 2025 | 70 | +2.9% | 51.08% | +9.74 pp | $73M | +24% |
| Q3 2025 | 68 | 1.4% | 41.34% | +11.01 pp | $59M | +36% |
| Q2 2025 | 69 | 15% | 30.33% | 0.80 pp | $44M | 2.6% |
| Q1 2025 | 81 | +1.3% | 31.13% | 19.68 pp | $45M | 39% |
| Q4 2024 | 80 | +11% | 50.81% | 21.76 pp | $73M | 30% |
| Q3 2024 | 72 | 12% | 72.57% | +0.82 pp | $104M | +1.1% |
| Q2 2024 | 82 | β | 71.75% | β | $103M | β |
Source: SEC 13F institutional filings. Ownership % requires market cap data and will show once linked. Ξ columns compare to the immediately prior filed quarter.
Quick answers to the most common questions about buying ABOS stock.
Based on Q1 2026 13F filings, institutional ownership of Acumen Pharmaceuticals, Inc. stands at 74.2%, held across 83 reporting institutions.
RA CAPITAL MANAGEMENT, L.P. is the largest reported institutional holder of ABOS, with approximately 20,992,669 shares worth $0.05B as of Q1 2026.
Yes β 4 widely-followed marquee investors appear among the top 25 institutional holders of ABOS, including SUSQUEHANNA INTERNATIONAL GROUP, LLP, MILLENNIUM MANAGEMENT LLC, TWO SIGMA INVESTMENTS, LP, RENAISSANCE TECHNOLOGIES LLC.
Our composite Smart Money Score for ABOS is 77 out of 100 (Bullish). It combines net institutional buying activity, ownership shift, marquee investor presence, and holder-count growth.
22 institutions opened new positions in ABOS during Q1 2026, while 9 fully exited. 53 added to existing positions and 7 trimmed.
ABOS institutional ownership rose by 23.10 percentage points quarter-over-quarter, with a net change of +13 holders.
The top 10 institutions account for 84.1% of all reported 13F value in ABOS, and the top 25 account for 97.1%.
All data is sourced from SEC Form 13F filings, which institutional investment managers with at least $100M in assets are required to file each quarter. We process every 13F filing from EDGAR and recompute the aggregates after each cycle. Insider transactions are sourced from Form 4 filings.
Acumen Pharmaceuticals, Inc. (ABOS) Institutional Ownership