Comparable stake leader
RA CAPITAL MANAGEMENT, L.P.
SEC ownership of Acumen Pharmaceuticals, Inc.
Top holders, 13D/G large-stake signals, insider positions, and transaction flow tied to CIK 0001576885.
Disclosed value leader
RA CAPITAL MANAGEMENT, L.P.
Comparable rows
50/50
Latest evidence
15 Jun 2026
- Public ticker
- ABOS on Nasdaq
- Parsed ownership sources
-
13D/G, 3/4/5, and 13F
Source: Parsed SEC ownership filingsUse: Compare filing families carefully
- Largest SEC-reported holder
-
RA CAPITAL MANAGEMENT, L.P.
Ranking: Comparable ownership first, then disclosed value
- Comparable ownership rows
-
50 of 50
Meaning: Rows with safely comparable ownership %
- Latest 13D/G holder
-
RA CAPITAL MANAGEMENT, L.P.
Source: Latest parsed Schedule 13D/G stake
- Latest parsed ownership date
-
15 Jun 2026
Freshness: Most recent filing date in this holder set
- Issuer CIK
- 0001576885
- Issuer location
- Newton, MA
Ownership snapshot
CIK-linked ownership evidence from parsed SEC filings.
3 signals
Issuer
Names, identifiers, and filing context for this profile.
2 identity fields
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.
Comparable stake leader
RA CAPITAL MANAGEMENT, L.P.
Disclosed value leader
RA CAPITAL MANAGEMENT, L.P.
Comparable rows
50/50
Latest evidence
15 Jun 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.
Quick read
RA CAPITAL MANAGEMENT, L.P. leads the comparable SEC ownership view at 30%.
50 of 50 rows have a safely comparable ownership percentage. Use this as a filing-backed starting point, then open the detailed table for source links, reporting role, position value, share count, and filing date.
Open SEC evidence
Opens RA CAPITAL MANAGEMENT, L.P.'s linked filing trail.
Comparable ownership
Top 5
RA CAPITAL MANAGEMENT, L.P.
30%
Sands Capital Alternatives, LLC
5.6%
James B. Murray Jr.
5%
FRANKLIN RESOURCES INC
3.8%
Derrell Porter
0.05%
Ownership % is shown only when SEC disclosures are safely comparable across share classes.
Detailed SEC evidence table Showing 1-8 of 50 holder rows
| 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 |
| Derrell Porter |
3/4/5
Director
|
0.05%
|
$82,537
35,500 shares
|
-$75,240 | 15 Jun 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 |
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: -$625,431.
Buys
$0
Insiders: 0
Sells
$625,431
Insiders: 9
Net
-$625,431
Shares: -305,128
Window
Last 12 months
4 rolling buckets
Buy value
Sell value
Shares: 0
Shares: 305,128
| Window (months) | Buy shares | Sell shares | Buy value | Sell value | Net value |
|---|---|---|---|---|---|
| 0-3 | 0 | 38,700 | $0 | $89,512 | -$89,512 |
| 3-6 | 0 | 11,496 | $0 | $35,125 | -$35,125 |
| 6-9 | 0 | 254,932 | $0 | $500,794 | -$500,794 |
| 9-12 | 0 | 0 | $0 | $0 | $0 |
Reporting owners
Insider holders from Forms 3/4/5
Showing 1-20 of 23 reporting-owner rows connected to Acumen Pharmaceuticals, Inc.. Open a relationship link for the CIK-to-CIK filing trail.
Rows
23
Largest Forms 3/4/5 holder
Sands Capital Ventures Discovery Fund III, L.P.
Net 12M change
-$625,431
Latest report
15 Jun 2026
| Name | Relationship | Holdings Value | Past Year Net Change | Change % | Valuation | Report Date |
|---|---|---|---|---|---|---|
| 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 |
| John A. Stalfort III | Director | $520,672 | Mixed | 03 Jun 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 |
| Amy Schacterle | Chief Regulatory Officer | $194,740 | -$2,176 | -1.1% | Mixed | 16 Jan 2026 |
| RA Capital Healthcare Fund LP | Director, 10%+ Owner | $113,988 | Mixed | 03 Jun 2026 | ||
| Laura Stoppel | Director | $113,988 | Mixed | 03 Jun 2026 | ||
| Rajeev M. Shah | Director, 10%+ Owner | $113,988 | Mixed | 03 Jun 2026 | ||
| Kimberlee C. Drapkin | Director | $113,988 | Mixed | 03 Jun 2026 | ||
| Jeffrey L. Ives | Director | $113,988 | Mixed | 03 Jun 2026 | ||
| Peter Kolchinsky | Director, 10%+ Owner | $113,988 | Mixed | 03 Jun 2026 | ||
| RA Capital Nexus Fund II, L.P. | Director | $113,988 | Mixed | 03 Jun 2026 | ||
| RA CAPITAL MANAGEMENT, L.P. | Director, 10%+ Owner | $113,988 | Mixed | 03 Jun 2026 | ||
| Nathan B. Fountain | Director | $107,379 | -$14,273 | -12% | Filing P/S | 09 Jun 2026 |
Recent insider transactions for Acumen Pharmaceuticals, Inc.
Showing up to 300 recent insider transactions from the last 12 months.
| Insider | Symbol | Class | Transaction | % | SEC-reported value | SEC-reported price | Shares | Shares owned | Date | Ownership |
|---|---|---|---|---|---|---|---|---|---|---|
| Derrell Porter | ABOS | Common Stock | Sale | -26.9% | $30,318 | $2.32 | -13,040 | 35,500 | 17 Jun 2026 | Direct |
| Derrell Porter | ABOS | Common Stock | Options Exercise | 36.7% | 13,040 | 48,540 | 17 Jun 2026 | Direct | ||
| Derrell Porter | ABOS | Stock Option (right to buy) | Options Exercise | -100% | -13,040 | 0 | 17 Jun 2026 | Direct | ||
| Derrell Porter | ABOS | Common Stock | Sale | -26.5% | $29,773 | $2.33 | -12,800 | 35,500 | 16 Jun 2026 | Direct |
| Derrell Porter | ABOS | Common Stock | Sale | -11.8% | $15,149 | $2.34 | -6,460 | 48,300 | 15 Jun 2026 | Direct |
| Derrell Porter | ABOS | Common Stock | Options Exercise | 13.4% | 6,460 | 54,760 | 15 Jun 2026 | Direct | ||
| Derrell Porter | ABOS | Stock Option (right to buy) | Options Exercise | -33.1% | -6,460 | 13,040 | 15 Jun 2026 | Direct | ||
| Nathan B. Fountain | ABOS | Common Stock | Sale | -11.7% | $14,273 | $2.23 | -6,400 | 48,150 | 09 Jun 2026 | Direct |
| RA CAPITAL MANAGEMENT, L.P. | ABOS | Common Stock | Award | 277.3% | 35,500 | 48,300 | 03 Jun 2026 | See footnotes | ||
| RA CAPITAL MANAGEMENT, L.P. | ABOS | Common Stock | Award | 277.3% | 35,500 | 48,300 | 03 Jun 2026 | See footnotes | ||
| Ra Capital Management, L.P. | ABOS | Common Stock | Award | 277.3% | 35,500 | 48,300 | 03 Jun 2026 | See footnotes | ||
| Ra Capital Management, L.P. | ABOS | Common Stock | Award | 277.3% | 35,500 | 48,300 | 03 Jun 2026 | See footnotes | ||
| Ra Capital Management, L.P. | ABOS | Common Stock | Award | 277.3% | 35,500 | 48,300 | 03 Jun 2026 | See footnotes | ||
| RA CAPITAL MANAGEMENT, L.P. | ABOS | Stock Option (Right to Buy) | Award | 53,250 | 53,250 | 03 Jun 2026 | See Footnotes | |||
| RA CAPITAL MANAGEMENT, L.P. | ABOS | Stock Option (Right to Buy) | Award | 53,250 | 53,250 | 03 Jun 2026 | See Footnotes | |||
| Ra Capital Management, L.P. | ABOS | Stock Option (Right to Buy) | Award | 53,250 | 53,250 | 03 Jun 2026 | See Footnotes | |||
| Ra Capital Management, L.P. | ABOS | Stock Option (Right to Buy) | Award | 53,250 | 53,250 | 03 Jun 2026 | See Footnotes | |||
| Ra Capital Management, L.P. | ABOS | Stock Option (Right to Buy) | Award | 53,250 | 53,250 | 03 Jun 2026 | See Footnotes | |||
| Nathan B. Fountain | ABOS | Common Stock | Award | 186.4% | 35,500 | 54,550 | 03 Jun 2026 | Direct | ||
| Nathan B. Fountain | ABOS | Stock Option (right to buy) | Award | 53,250 | 53,250 | 03 Jun 2026 | Direct | |||
| Kimberlee C. Drapkin | ABOS | Common Stock | Award | 277.3% | 35,500 | 48,300 | 03 Jun 2026 | Direct | ||
| Kimberlee C. Drapkin | ABOS | Stock Option (right to buy) | Award | 53,250 | 53,250 | 03 Jun 2026 | Direct | |||
| John A. Stalfort III | ABOS | Common Stock | Award | 19.2% | 35,500 | 220,624 | 03 Jun 2026 | Direct | ||
| John A. Stalfort III | ABOS | Stock Option (right to buy) | Award | 53,250 | 53,250 | 03 Jun 2026 | Direct | |||
| Derrell Porter | ABOS | Common Stock | Award | 277.3% | 35,500 | 48,300 | 03 Jun 2026 | Direct | ||
| Derrell Porter | ABOS | Stock Option (right to buy) | Award | 53,250 | 53,250 | 03 Jun 2026 | Direct | |||
| Jeffrey L. Ives | ABOS | Common Stock | Award | 277.3% | 35,500 | 48,300 | 03 Jun 2026 | Direct | ||
| Jeffrey L. Ives | ABOS | Stock Option (right to buy) | Award | 53,250 | 53,250 | 03 Jun 2026 | Direct | |||
| George Golumbeski | ABOS | Common Stock | Award | 35,500 | 35,500 | 03 Jun 2026 | Direct | |||
| George Golumbeski | ABOS | Stock Option (right to buy) | Award | 53,250 | 53,250 | 03 Jun 2026 | Direct | |||
| Laura Stoppel | ABOS | Common Stock | Award | 277.3% | 35,500 | 48,300 | 03 Jun 2026 | Direct | ||
| Laura Stoppel | ABOS | Stock Option (right to buy) | Award | 53,250 | 53,250 | 03 Jun 2026 | Direct | |||
| 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 |
* marks a reported price that did not pass the local price check.