Acumen Pharmaceuticals, Inc.
Acumen Pharmaceuticals, Inc. (ABOS) Stock Ownership
Institutional vs insider vs public ownership from 13F and float data — top holders, activity, and insider trades below.
SEC 13F · FMP · ABOS · as of Sep 30, 2025
Ownership Breakdown
70
Institutional Holders
▼ 3 vs Q2
$61.10M
Total Inst. Value
▲ $17.46M vs Q2
60.57M
Shares Outstanding
freeFloat 76.52%
35.73M
13F Shares Held
▼ 1.88M vs Q2
Institutional ownership = 13F shares ÷ total outstanding. Insider % = 100 − free float. Public % = free float − institution %. Data: FMP /symbol-positions-summary + /shares-float + SEC EDGAR.
Top Institutional Holders
ABOS largest shareholders · institutional ownership
Q3 2025 · SEC 13F
Showing top 10 holders
| Holder | Shares | % Owned | Weight | Value | Reported | Change |
|---|---|---|---|---|---|---|
RA CAPITAL MANAGEMENT, L.P. biological products, (no diagnostic substances) | 14.93M | 24.65% | 24.65% | $25.53B | Nov 14, 2025 | — held |
SANDS CAPITAL VENTURES, LLC biological products, (no diagnostic substances) | 3.42M | 5.64% | 5.64% | $5.84B | Nov 13, 2025 | — held |
FRANKLIN RESOURCES INC biological products, (no diagnostic substances) | 2.31M | 3.81% | 3.81% | $3.94B | Nov 13, 2025 | ▼ 771.9K |
FMR LLC biological products, (no diagnostic substances) | 2.03M | 3.35% | 3.35% | $3.47B | Nov 13, 2025 | ▼ 411 |
VANGUARD GROUP INC biological products, (no diagnostic substances) | 1.65M | 2.73% | 2.73% | $2.82B | Nov 7, 2025 | ▼ 37.9K |
KNOLLWOOD INVESTMENT ADVISORY, LLC biological products, (no diagnostic substances) | 1.63M | 2.69% | 2.69% | $2.78B | Nov 14, 2025 | — held |
ALYESKA INVESTMENT GROUP, L.P. biological products, (no diagnostic substances) | 939.6K | 1.55% | 1.55% | $1.61B | Nov 17, 2025 | — held |
ADAR1 CAPITAL MANAGEMENT, LLC biological products, (no diagnostic substances) | 891.2K | 1.47% | 1.47% | $1.52B | Nov 14, 2025 | ▼ 25.0K |
LAURION CAPITAL MANAGEMENT LP biological products, (no diagnostic substances) | 867.0K | 1.43% | 1.43% | $1.48B | Nov 17, 2025 | — held |
PATHSTONE HOLDINGS, LLC biological products, (no diagnostic substances) | 859.1K | 1.42% | 1.42% | $1.47B | Nov 13, 2025 | ▼ 199.4K |
Data from SEC Form 13F filings. Ownership bar normalised to largest holder. Change flags: isNew / isSoldOut / changeInSharesNumber (FMP extract-analytics/holder).
Institutional Activity
Q3 2025 vs prior quarter
Q3 2025
8
Increased
+989.0K shares5
New Positions
first time holders20
Decreased
−2.91M shares0
Sold Out
fully exitedNet shares change (top 50)
1.92M
+989.0K / −2.91M
Net new holders
-7
5 new / 0 exited
Based on top 50 institutional holders by position size. Fields: isNew, isSoldOut, changeInSharesNumber (FMP extract-analytics/holder, limit=50).
Insider Buying vs Selling
ABOS insider trading · insider activity
Source: SEC Form 4
Insiders have been primarily selling shares recently. Selling may be driven by pre-scheduled Rule 10b5-1 plans rather than negative sentiment.
16
Buy transactions
0
Sell transactions
0.00
Buy/Sell ratio
$0M
Total disposed
Recent Insider Transactions
Showing 10 most recent · Common Stock only
| Name · Role | Date | Type | Shares | Price | Value | After Trans. | Filing |
|---|---|---|---|---|---|---|---|
RA CAPITAL MANAGEMENT, L.P.
| Jun 3, 2026 | Award | 53,250 | $2.29 | $121.9K | 53.3K | Form 4 ↗ |
RA CAPITAL MANAGEMENT, L.P.
| Jun 3, 2026 | Award | 35,500 | — | — | 48.3K | Form 4 ↗ |
Fountain Nathan B director | Jun 3, 2026 | Award | 35,500 | — | — | 54.5K | Form 4 ↗ |
Fountain Nathan B director | Jun 3, 2026 | Award | 53,250 | $2.29 | $121.9K | 53.3K | Form 4 ↗ |
Drapkin Kimberlee C director | Jun 3, 2026 | Award | 53,250 | $2.29 | $121.9K | 53.3K | Form 4 ↗ |
Drapkin Kimberlee C director | Jun 3, 2026 | Award | 35,500 | — | — | 48.3K | Form 4 ↗ |
Stalfort John A III director | Jun 3, 2026 | Award | 35,500 | — | — | 220.6K | Form 4 ↗ |
Stalfort John A III director | Jun 3, 2026 | Award | 53,250 | $2.29 | $121.9K | 53.3K | Form 4 ↗ |
Porter Derrell director | Jun 3, 2026 | Award | 53,250 | $2.29 | $121.9K | 53.3K | Form 4 ↗ |
Porter Derrell director | Jun 3, 2026 | Award | 35,500 | — | — | 48.3K | Form 4 ↗ |
Source: /insider-trading/search (FMP stable). Buy/Sell direction: acquisitionOrDisposition A=Buy, D=Sell. RSU vesting (M-Exempt) excluded from sentiment bar. All data from SEC EDGAR public filings.
About institutional & insider ownership
Acumen Pharmaceuticals, Inc. (ABOS) is primarily owned by institutional investors, who hold approximately 59.0% of total shares outstanding. Company insiders own approximately 23.48%, while retail and public investors account for the remaining 17.53%.
The largest institutional shareholder of Acumen Pharmaceuticals, Inc. is RA CAPITAL MANAGEMENT, L.P., holding approximately 14.93 million shares — equal to 24.65% of outstanding shares — as of September 30, 2025.
A total of 70 institutional investors currently hold ABOS stock, with a combined institutional value of approximately $61,098,682 as of the most recent 13F filing period.
Frequently asked questions
ABOS ownershipAcumen Pharmaceuticals, Inc. (ABOS) is primarily owned by institutional investors, who hold approximately 59.0% of shares. The largest shareholder is RA CAPITAL MANAGEMENT, L.P. with a 24.65% stake. Company insiders hold 23.48%. Data sourced from SEC Form 13F as of September 30, 2025.