Holder evidence
50
SEC ownership of Acumen Pharmaceuticals, Inc.
Top holders, 13D/G large-stake signals, insider positions, and transaction flow tied to CIK 0001576885.
Lead holder
RA CAPITAL MANAGEMENT, L.P.
13D/G signal
RA CAPITAL MANAGEMENT, L.P.
Latest evidence
31 Mar 2026
- CIK
- 0001576885
- Symbol
- ABOS on Nasdaq
- Location
- Newton, MA
- SEC evidence mix
- 13D/G, 3/4/5, and 13F
- Lead holder
- RA CAPITAL MANAGEMENT, L.P.
- Latest large-stake holder
- RA CAPITAL MANAGEMENT, L.P.
- Latest evidence date
- 31 Mar 2026
Issuer identity
Ownership snapshot
Ownership snapshot
Top shareholders of Acumen Pharmaceuticals, Inc. (13F + 13D/G + 3/4/5)
Grouped by holder across the latest SEC ownership disclosures. Start with comparable ownership when available, then verify the linked 13F, 13D/G, or 3/4/5 evidence.
Lead holder
RA CAPITAL MANAGEMENT, L.P.
13D/G signal
RA CAPITAL MANAGEMENT, L.P.
Evidence rows
50
Latest as of
31 Mar 2026
13D/G
3/4/5
13F
Lead comparable stake: 30%
13D/G row: RA CAPITAL MANAGEMENT, L.P.
Showing 1-8 of 50 holder rows.
Rank 1 holder
RA CAPITAL MANAGEMENT, L.P.
13D/G
3/4/5
13F
- Ownership
- 30%
- Position
- $55.08M
Rank 2 holder
Sands Capital Alternatives, LLC
13F
13D/G
- Ownership
- 5.6%
- Position
- $8.78M
Rank 3 holder
James B. Murray Jr.
13D/G
- Ownership
- 5%
- Position
- $9.43M
| Holder | Evidence | Ownership % | Position | 12M Net Δ | As of |
|---|---|---|---|---|---|
| RA CAPITAL MANAGEMENT, L.P. |
13D/G
3/4/5
13F
Director, 10%+ Owner · Company
|
30%
|
$55,075,356
21,101,669 shares
|
+$15,883,432 | 13 Mar 2026 |
| Sands Capital Alternatives, LLC |
13F
13D/G
Company
|
5.6%
from 13D/G
|
$8,779,448
3,720,105 shares
|
— | 31 Mar 2026 |
| James B. Murray Jr. |
13D/G
|
5%
|
$9,425,650
3,611,360 shares
|
$0 | 04 Apr 2025 |
| FRANKLIN RESOURCES INC |
13F
13D/G
Company
|
3.8%
from 13D/G
|
$5,440,027
2,305,096 shares
|
— | 31 Mar 2026 |
| Alyeska Investment Group, L.P. |
13F
Company
|
3.4%
|
$5,776,765
2,454,754 shares
|
— | 31 Mar 2026 |
| ADAR1 Capital Management, LLC |
13F
Company
|
3%
|
$5,088,948
2,156,334 shares
|
— | 31 Mar 2026 |
| Knollwood Investment Advisory, LLC |
13F
Company
|
2.3%
|
$3,843,284
1,628,510 shares
|
— | 31 Mar 2026 |
| VANGUARD CAPITAL MANAGEMENT LLC |
13F
Company
|
2.1%
|
$3,554,814
1,506,277 shares
|
— | 31 Mar 2026 |
How to read this table
Rows are grouped by holder and ranked first by SEC-reported ownership % when it is safely comparable, then by disclosed holdings value. — indicates unavailable or non-comparable values; "mixed-class rows" means the latest filing spans non-comparable classes.
Forms 3/4/5 flow
Insider trading overview
Net insider flow leans to selling over the last 12 months. Net value: -$535,919.
Buys
$0
Insiders: 0
Sells
$535,919
Insiders: 7
Net
-$535,919
Shares: -266,428
Window
Last 12 months
4 rolling buckets
Buy value
Sell value
Shares: 0
Shares: 266,428
| Window (months) | Buy shares | Sell shares | Buy value | Sell value | Net value |
|---|---|---|---|---|---|
| 0-3 | 0 | 2,090 | $0 | $6,813 | -$6,813 |
| 3-6 | 0 | 264,338 | $0 | $529,105 | -$529,105 |
| 6-9 | 0 | 0 | $0 | $0 | $0 |
| 9-12 | 0 | 0 | $0 | $0 | $0 |
Reporting owners
Insider holders from Forms 3/4/5
Showing 1-19 of 19 reporting-owner rows connected to Acumen Pharmaceuticals, Inc.. Open a relationship link for the CIK-to-CIK filing trail.
Rows
19
Lead holder
RA CAPITAL MANAGEMENT, L.P.
Net 12M change
-$535,918
Latest report
16 Mar 2026
| Name | Relationship | Holdings Value | Past Year Net Change | Change % | Valuation | Report Date |
|---|---|---|---|---|---|---|
| RA CAPITAL MANAGEMENT, L.P. | Director, 10%+ Owner | $49,860,878 | Mixed | 16 Mar 2026 | ||
| Sands Capital Ventures Discovery Fund III, L.P. | 10%+ Owner | $11,859,300 | Mixed | 06 Jul 2021 | ||
| Paul B. Manning | 10%+ Owner | $2,283,603 | Mixed | 06 Jul 2021 | ||
| Robert D. Hardie | 10%+ Owner | $2,283,603 | Mixed | 06 Jul 2021 | ||
| Daniel Joseph OConnell | Chief Executive Officer, Director | $1,660,145 | -$163,123 | -8.9% | Filing P/S | 21 Jan 2026 |
| Derek M. Meisner | Chief Legal Officer & Corp Sec | $567,236 | -$248,888 | -30% | Filing P/S | 06 Mar 2026 |
| Matt Zuga | CFO & Chief Business Officer | $567,158 | -$49,556 | -8% | Filing P/S | 21 Jan 2026 |
| James J. Doherty | President and CDO | $466,054 | -$15,148 | -3.1% | Mixed | 16 Jan 2026 |
| Eric Siemers | Chief Medical Officer | $464,775 | -$27,110 | -5.5% | Filing P/S | 21 Jan 2026 |
| Russell Barton | Chief Operating Officer | $377,369 | -$29,917 | -7.3% | Filing P/S | 21 Jan 2026 |
| John A. Stalfort III | Director | $203,636 | Mixed | 04 Jun 2025 | ||
| Amy Schacterle | Chief Regulatory Officer | $194,740 | -$2,176 | -1.1% | Mixed | 16 Jan 2026 |
| Nathan B. Fountain | Director | $20,955 | Mixed | 04 Jun 2025 | ||
| Laura Stoppel | Director | $14,080 | Mixed | 04 Jun 2025 | ||
| Kimberlee C. Drapkin | Director | $14,080 | Mixed | 04 Jun 2025 | ||
| Derrell Porter | Director | $14,080 | Mixed | 04 Jun 2025 | ||
| Jeffrey L. Ives | Director | $14,080 | Mixed | 04 Jun 2025 | ||
| George Golumbeski | Director | Mixed | 06 Nov 2025 | |||
| Jeffrey Sevigny | Director | Mixed | 15 Jun 2022 |
Recent insider transactions for Acumen Pharmaceuticals, Inc.
Showing up to 300 most recent insider transactions from the last 12 months.
| Insider | Symbol | Class | Transaction | % | Reported value | Reported price | Shares | Shares owned | Date | Ownership |
|---|---|---|---|---|---|---|---|---|---|---|
| Ra Capital Management, L.P. | ABOS | Common Stock | Award | 46.5% | 6,060,606 | 19,103,785 | 16 Mar 2026 | See footnotes | ||
| Derek M. Meisner | ABOS | Common Stock | Sale | -1.19% | $6,813 | $3.26 | -2,090 | 173,999 | 06 Mar 2026 | Direct |
| Derek M. Meisner | ABOS | Common Stock | Options Exercise | 1.2% | 2,090 | 176,089 | 06 Mar 2026 | Direct | ||
| Derek M. Meisner | ABOS | Employee Stock Option (right to buy) | Options Exercise | -2.86% | -2,090 | 71,048 | 06 Mar 2026 | Direct | ||
| Derek M. Meisner | ABOS | Common Stock | Sale | -5.13% | $28,311 | $3.01 | -9,406 | 173,999 | 27 Feb 2026 | Direct |
| Derek M. Meisner | ABOS | Common Stock | Options Exercise | 5.41% | 9,406 | 183,405 | 27 Feb 2026 | Direct | ||
| Derek M. Meisner | ABOS | Employee Stock Option (right to buy) | Options Exercise | -11.4% | -9,406 | 73,138 | 27 Feb 2026 | Direct | ||
| Derek M. Meisner | ABOS | Common Stock | Sale | -1.51% | $8,017 | $3.00 | -2,671 | 173,999 | 28 Jan 2026 | Direct |
| Derek M. Meisner | ABOS | Common Stock | Options Exercise | 1.54% | 2,671 | 176,670 | 28 Jan 2026 | Direct | ||
| Derek M. Meisner | ABOS | Employee Stock Option (right to buy) | Options Exercise | -3.13% | -2,671 | 82,544 | 28 Jan 2026 | Direct | ||
| Derek M. Meisner | ABOS | Common Stock | Sale | -7.98% | $45,263 | $3.00 | -15,085 | 173,999 | 26 Jan 2026 | Direct |
| Derek M. Meisner | ABOS | Common Stock | Options Exercise | 8.67% | 15,085 | 189,084 | 26 Jan 2026 | Direct | ||
| Derek M. Meisner | ABOS | Employee Stock Option (right to buy) | Options Exercise | -15% | -15,085 | 85,215 | 26 Jan 2026 | Direct | ||
| Derek M. Meisner | ABOS | Common Stock | Sale | -3.14% | $10,718 | $1.90 | -5,633 | 173,999 | 23 Jan 2026 | Direct |
| Derek M. Meisner | ABOS | Common Stock | Sale | -0.58% | $1,939 | $1.84 | -1,054 | 179,632 | 22 Jan 2026 | Direct |
| Eric Siemers | ABOS | Common Stock | Sale | -0.35% | $1,629 | $1.82 | -895 | 255,371 | 22 Jan 2026 | Direct |
| Matt Zuga | ABOS | Common Stock | Sale | -0.55% | $3,138 | $1.86 | -1,687 | 304,924 | 22 Jan 2026 | Direct |
| Daniel Joseph OConnell | ABOS | Common Stock | Sale | -0.3% | $5,066 | $1.88 | -2,689 | 881,275 | 22 Jan 2026 | Direct |
| Russell Barton | ABOS | Common Stock | Sale | -0.22% | $850 | $1.84 | -462 | 205,092 | 22 Jan 2026 | Direct |
| Derek M. Meisner | ABOS | Common Stock | Sale | -1.23% | $4,063 | $1.81 | -2,247 | 180,686 | 21 Jan 2026 | Direct |
| Eric Siemers | ABOS | Common Stock | Sale | -0.9% | $4,204 | $1.80 | -2,331 | 256,266 | 21 Jan 2026 | Direct |
| Matt Zuga | ABOS | Common Stock | Sale | -0.8% | $4,469 | $1.81 | -2,473 | 306,611 | 21 Jan 2026 | Direct |
| Daniel Joseph OConnell | ABOS | Common Stock | Sale | -1.05% | $16,927 | $1.81 | -9,346 | 883,964 | 21 Jan 2026 | Direct |
| Russell Barton | ABOS | Common Stock | Sale | -1.11% | $4,181 | $1.81 | -2,315 | 205,554 | 21 Jan 2026 | Direct |
| Daniel Joseph OConnell | ABOS | Common Stock | Award | 50.5% | 299,800 | 893,310 | 20 Jan 2026 | Direct | ||
| Daniel Joseph OConnell | ABOS | Employee Stock Option (right to buy) | Award | 450,000 | 450,000 | 20 Jan 2026 | Direct | |||
| Matt Zuga | ABOS | Common Stock | Award | 47.2% | 99,133 | 309,084 | 16 Jan 2026 | Direct | ||
| Matt Zuga | ABOS | Employee Stock Option (right to buy) | Award | 148,700 | 148,700 | 16 Jan 2026 | Direct | |||
| Derek M. Meisner | ABOS | Common Stock | Award | 118.3% | 99,133 | 182,933 | 16 Jan 2026 | Direct | ||
| Derek M. Meisner | ABOS | Employee Stock Option (right to buy) | Award | 148,700 | 148,700 | 16 Jan 2026 | Direct | |||
| Eric Siemers | ABOS | Common Stock | Award | 62.2% | 99,133 | 258,597 | 16 Jan 2026 | Direct | ||
| Eric Siemers | ABOS | Employee Stock Option (right to buy) | Award | 148,700 | 148,700 | 16 Jan 2026 | Direct | |||
| Russell Barton | ABOS | Common Stock | Award | 68.6% | 84,600 | 207,869 | 16 Jan 2026 | Direct | ||
| Russell Barton | ABOS | Employee Stock Option (right to buy) | Award | 126,900 | 126,900 | 16 Jan 2026 | Direct | |||
| Amy Schacterle | ABOS | Common Stock | Award | 1098.3% | 84,600 | 92,303 | 16 Jan 2026 | Direct | ||
| Amy Schacterle | ABOS | Employee Stock Option (right to buy) | Award | 126,900 | 126,900 | 16 Jan 2026 | Direct | |||
| James J. Doherty | ABOS | Common Stock | Award | 308.8% | 166,867 | 220,900 | 16 Jan 2026 | Direct | ||
| James J. Doherty | ABOS | Employee Stock Option (right to buy) | Award | 250,300 | 250,300 | 16 Jan 2026 | Direct | |||
| Derek M. Meisner | ABOS | Common Stock | Sale | -9.26% | $14,658 | $1.71 | -8,548 | 83,800 | 12 Jan 2026 | Direct |
| Daniel Joseph OConnell | ABOS | Common Stock | Sale | -0.9% | $9,307 | $1.73 | -5,388 | 593,510 | 12 Jan 2026 | Direct |
| Derek M. Meisner | ABOS | Common Stock | Sale | -5.33% | $9,169 | $1.76 | -5,200 | 92,348 | 09 Jan 2026 | Direct |
| Daniel Joseph OConnell | ABOS | Common Stock | Sale | -2.12% | $22,832 | $1.76 | -12,941 | 598,898 | 09 Jan 2026 | Direct |
| Matt Zuga | ABOS | Common Stock | Sale | -3.18% | $12,513 | $1.82 | -6,888 | 209,951 | 08 Jan 2026 | Direct |
| Russell Barton | ABOS | Common Stock | Sale | -2.78% | $6,562 | $1.86 | -3,530 | 123,269 | 08 Jan 2026 | Direct |
| Derek M. Meisner | ABOS | Common Stock | Sale | -27.4% | $67,246 | $1.82 | -36,911 | 97,548 | 08 Jan 2026 | Direct |
| Daniel Joseph OConnell | ABOS | Common Stock | Sale | -1.31% | $14,815 | $1.82 | -8,143 | 611,839 | 08 Jan 2026 | Direct |
| James J. Doherty | ABOS | Common Stock | Sale | -10.7% | $11,769 | $1.82 | -6,467 | 54,033 | 08 Jan 2026 | Direct |
| James J. Doherty | ABOS | Common Stock | Sale | -2.73% | $3,379 | $1.99 | -1,700 | 60,500 | 07 Jan 2026 | Direct |
| Amy Schacterle | ABOS | Common Stock | Sale | -12.5% | $2,176 | $1.98 | -1,097 | 7,703 | 07 Jan 2026 | Direct |
| Matt Zuga | ABOS | Common Stock | Sale | -2.61% | $11,566 | $1.99 | -5,805 | 216,839 | 07 Jan 2026 | Direct |
* indicates a reported price that failed the local validity check.