Institutional HoldersBeta

Who holds a company, from every 13F filed for the quarter, one row per filer exactly as filed, against the latest share count the company reported.

Acumen Pharmaceuticals, Inc.

CIK 0001576885ABOS· quarter ending 2026-06-30

Shares outstanding

72,317,285

as of 2026-08-07 · 10-Q cover page, filed 2026-08-12

Held by 13F filers

47,856,762

66.2% of shares outstanding

Holders

+12 vs 2026-03-31 · 30 new, 18 exited

Value

$127.8M

shares +4.0% vs prior quarter

Share classes (cover page of the 10-Q filed 2026-08-12, as of 2026-08-07)

Class	Listed	Shares outstanding	Held by 13F filers	% of class	Holders	CUSIP
Common stock	ABOS · NASDAQ	72,317,285	47,856,762	66.2%	96	00509G209

Each class is compared with its own share count; classes are not added together. A class that is not exchange-listed cannot be held by 13F filers.

Securities (CUSIPs held in 13F this quarter)

tick to combine

Count	CUSIP	Class (as filers write it)	Holders	Shares held	Class shares	% of class	Value	Options	Mapped via
	00509G209	COM	96	47,856,762	72,317,285	66.2%	$127.8M	1 call / 0 put	13DG	holders →

Totals combine the ticked CUSIPs and update as you tick: common-stock classes by default; preferreds, notes, warrants and depositary shares are listed but not counted. "holders →" shows a single CUSIP on its own. Bonds are held as a principal amount, not shares. Options positions are never counted as holdings.

Top holders (96 of 96 · 00509G209)

change vs 2026-03-31

#	Filer	Shares	% of class	Value	Change
1	RA CAPITAL MANAGEMENT, L.P.	20,992,669	29.03%	$56.1M	—
2	Sands Capital Alternatives, LLC	3,720,105	5.14%	$9.9M	—
3	BlackRock, Inc.	2,490,115	3.44%	$6.6M	+2,311,789 (+1296.4%)
4	Alyeska Investment Group, L.P.	2,454,754	3.39%	$6.6M	—
5	FRANKLIN RESOURCES INC	2,305,096	3.19%	$6.2M	—
6	ADAR1 Capital Management, LLC	2,111,334	2.92%	$5.6M	-45,000 (-2.1%)
7	VANGUARD CAPITAL MANAGEMENT LLC	1,672,072	2.31%	$4.5M	+165,795 (+11.0%)
8	Knollwood Investment Advisory, LLC	1,628,510	2.25%	$4.3M	—
9	GEODE CAPITAL MANAGEMENT, LLC	1,141,858	1.58%	$3.0M	+725,620 (+174.3%)
10	Ikarian Capital, LLC	1,053,797	1.46%	$2.8M	—
11	Hudson Bay Capital Management LP	955,000	1.32%	$2.5M	-13,940 (-1.4%)
12	Pathstone Holdings, LLC	859,110	1.19%	$2.3M	—
13	RENAISSANCE TECHNOLOGIES LLC	675,025	0.93%	$1.8M	+201,079 (+42.4%)
14	TWO SIGMA INVESTMENTS, LP	622,882	0.86%	$1.7M	+92,070 (+17.3%)
15	STATE STREET CORP	600,528	0.83%	$1.6M	+448,800 (+295.8%)
16	NORTHERN TRUST CORP	360,744	0.50%	$963K	+285,532 (+379.6%)
17	VANGUARD PORTFOLIO MANAGEMENT LLC	320,795	0.44%	$857K	NEW
18	DIMENSIONAL FUND ADVISORS LP	291,559	0.40%	$779K	+171,803 (+143.5%)
19	VANGUARD FIDUCIARY TRUST CO	291,240	0.40%	$778K	+92,014 (+46.2%)
20	BANK OF AMERICA CORP /DE/	274,781	0.38%	$734K	-45,435 (-14.2%)
21	BOOTHBAY FUND MANAGEMENT, LLC	273,012	0.38%	$729K	—
22	ACADIAN ASSET MANAGEMENT LLC	270,338	0.37%	$718K	+84,488 (+45.5%)
23	NOMURA HOLDINGS INC	189,712	0.26%	$507K	NEW
24	GOLDMAN SACHS GROUP INC	183,927	0.25%	$491K	-22,756 (-11.0%)
25	BRIDGEWAY CAPITAL MANAGEMENT, LLC	176,171	0.24%	$470K	—
26	MORGAN STANLEY	136,763	0.19%	$365K	-7,821 (-5.4%)
27	SUSQUEHANNA INTERNATIONAL GROUP, LLP	126,104	0.17%	$337K	-475,372 (-79.0%)
28	Bank of New York Mellon Corp	124,377	0.17%	$332K	NEW
29	CHARLES SCHWAB INVESTMENT MANAGEMENT INC	115,099	0.16%	$307K	NEW
30	PFG Investments, LLC	94,250	0.13%	$252K	+13,400 (+16.6%)
31	CATALYST FINANCIAL PARTNERS LLC	89,699	0.12%	$239K	—
32	Nuveen, LLC	63,355	0.09%	$169K	NEW
33	MILLENNIUM MANAGEMENT LLC	60,598	0.08%	$162K	-599,077 (-90.8%)
34	Squarepoint Ops LLC	52,351	0.07%	$140K	+37,336 (+248.7%)
35	CITADEL ADVISORS LLC	51,049	0.07%	$136K	NEW
36	Prospera Financial Services Inc	50,000	0.07%	$134K	—
37	WELLS FARGO & COMPANY/MN	49,686	0.07%	$133K	+39,578 (+391.6%)
38	MARSHALL WACE, LLP	48,114	0.07%	$128K	-144,775 (-75.1%)
39	DEUTSCHE BANK AG\	46,132	0.06%	$123K	NEW
40	Verdad Advisers, LP	44,478	0.06%	$119K	+7,200 (+19.3%)
41	BARCLAYS PLC	39,655	0.05%	$106K	+8,976 (+29.3%)
42	PRICE T ROWE ASSOCIATES INC /MD/	39,327	0.05%	$106K	NEW
43	Qube Research & Technologies Ltd	38,614	0.05%	$103K	-81,774 (-67.9%)
44	NEW YORK STATE COMMON RETIREMENT FUND	36,200	0.05%	$97K	NEW
45	RHUMBLINE ADVISERS	35,034	0.05%	$94K	NEW
46	Rangeley Capital, LLC	35,000	0.05%	$93K	—
47	XTX Topco Ltd	32,134	0.04%	$86K	NEW
48	Intrepid Financial Planning Group LLC	30,150	0.04%	$81K	—
49	Y-Intercept (Hong Kong) Ltd	29,540	0.04%	$79K	NEW
50	Quantinno Capital Management LP	26,769	0.04%	$71K	NEW
51	UBS Group AG	25,765	0.04%	$69K	-11,381 (-30.6%)
52	Invesco Ltd.	24,588	0.03%	$66K	NEW
53	AXQ CAPITAL, LP	24,426	0.03%	$65K	-4,061 (-14.3%)
54	AMERICAN CENTURY COMPANIES INC	24,136	0.03%	$64K	+6,207 (+34.6%)
55	CITIGROUP INC	21,889	0.03%	$58K	+17,403 (+387.9%)
56	MIRAE ASSET GLOBAL ETFS HOLDINGS Ltd.	21,761	0.03%	$58K	NEW
57	JPMORGAN CHASE & CO	20,161	0.03%	$56K	+18,717 (+1296.2%)
58	Police & Firemen's Retirement System of New Jersey	19,393	0.03%	$52K	NEW
59	Independent Advisor Alliance	19,000	0.03%	$51K	—
60	Pinnacle Wealth Management Advisory Group, LLC	18,020	0.02%	$48K	—
61	PINNACLE ASSOCIATES LTD	18,020	0.02%	$48K	—
62	Factor Wealth Management LTD	16,500	0.02%	$44K	—
63	Spark Investment Management LLC	14,700	0.02%	$39K	NEW
64	STIFEL FINANCIAL CORP	12,900	0.02%	$34K	NEW
65	Virtu Financial LLC	11,940	0.02%	$32K	NEW
66	TWO SIGMA SECURITIES, LLC	11,892	0.02%	$32K	NEW
67	Balyasny Asset Management L.P.	11,872	0.02%	$32K	NEW
68	SEI INVESTMENTS CO	11,564	0.02%	$31K	—
69	BNP PARIBAS FINANCIAL MARKETS	11,329	0.02%	$30K	+10,121 (+837.8%)
70	Mesirow Financial Investment Management, Inc.	11,305	0.02%	$30K	—
71	Bronte Capital Management Pty Ltd.	10,716	0.01%	$29K	NEW
72	INTECH INVESTMENT MANAGEMENT LLC	10,446	0.01%	$28K	NEW
73	Integrated Wealth Concepts LLC	10,179	0.01%	$27K	—
74	Steward Partners Investment Advisory, LLC	10,000	0.01%	$27K	NEW
75	FMR LLC	7,530	0.01%	$20K	-1,149,816 (-99.3%)
76	OSAIC HOLDINGS, INC.	7,350	0.01%	$20K	+1,999 (+37.4%)
77	Vanguard Global Advisers, LLC	6,684	0.01%	$18K	—
78	Legal & General Group Plc	4,610	0.01%	$12K	NEW
79	Ameritas Investment Partners, Inc.	4,289	0.01%	$11K	NEW
80	Russell Investments Group, Ltd.	3,779	0.01%	$10K	NEW
81	PNC Financial Services Group, Inc.	3,080	0.00%	$8K	—
82	Rockefeller Capital Management L.P.	3,000	0.00%	$8K	—
83	Tower Research Capital LLC (TRC)	2,899	0.00%	$8K	+2,781 (+2356.8%)
84	TFC Financial Management, Inc.	2,500	0.00%	$7K	—
85	JONES FINANCIAL COMPANIES LLLP	2,000	0.00%	$5K	—
86	ROYAL BANK OF CANADA	1,561	0.00%	$4K	-5,529 (-78.0%)
87	NISA INVESTMENT ADVISORS, LLC	1,229	0.00%	$3K	—
88	US BANCORP \DE\	1,000	0.00%	$3K	—
89	Sterling Capital Management LLC	952	0.00%	$3K	NEW
90	GROUP ONE TRADING LLC	722	0.00%	$2K	-753 (-51.1%)
91	Avion Wealth	500	0.00%	$1K	NEW
92	EverSource Wealth Advisors, LLC	407	0.00%	$1K	—
93	SBI Securities Co., Ltd.	291	0.00%	$777	-12 (-4.0%)
94	Farther Finance Advisors, LLC	200	0.00%	$534	—
95	Caitong International Asset Management Co., Ltd	39	0.00%	$104	NEW
96	Arax Advisory Partners	26	0.00%	$69	—

Exited since 2026-03-31 (18 filers; largest 18 shown)

SG Americas Securities, LLC	−719,257
Laurion Capital Management LP	−525,444
JANE STREET GROUP, LLC	−89,661
Point72 Asset Management, L.P.	−67,375
Catalyst Funds Management Pty Ltd	−45,600
OMERS ADMINISTRATION Corp	−28,600
SIMPLEX TRADING, LLC	−17,414
CAPTRUST FINANCIAL ADVISORS	−15,757
Brevan Howard Capital Management LP	−15,385
HRT FINANCIAL LP	−13,162
JACOBS LEVY EQUITY MANAGEMENT, INC	−13,011
Schonfeld Strategic Advisors LLC	−11,300
Advisory Services Network, LLC	−1,111
NBT BANK N A /NY	−200
CWM, LLC	−87
Clearstead Advisors, LLC	−60
Larson Financial Group LLC	−20
Optiver Holding B.V.	−5

Large holders from 13D/13G (latest per reporting person, last 2 years)

Filed when a holder crosses 5% or changes materially, so often more current than the quarter-end 13F. Percentages are the filer's own, against the share count they used.

Reporting person	Form	Filed	Event	Shares	% of class
James B. Murray Jr.	SCHEDULE 13G	2026-04-07	2025-04-04	3,611,360	5%
Rajeev Shah	SCHEDULE 13D/A	2026-03-17	2026-03-13	21,101,669	29.5%
Peter Kolchinsky	SCHEDULE 13D/A	2026-03-17	2026-03-13	21,101,669	29.5%
RA Capital Healthcare Fund, L.P.	SCHEDULE 13D/A	2026-03-17	2026-03-13	19,103,785	26.8%
RA Capital Management, L.P.	SCHEDULE 13D/A	2026-03-17	2026-03-13	21,101,669	29.5%
Franklin Resources, Inc.	SCHEDULE 13G/A	2025-11-04	2025-09-30	2,305,096	3.8%
Charles B. Johnson	SCHEDULE 13G/A	2025-11-04	2025-09-30	0	0%
Rupert H. Johnson, Jr.	SCHEDULE 13G/A	2025-11-04	2025-09-30	0	0%
Sands Capital Alternatives, LLC	SCHEDULE 13G/A	2025-08-13	2025-06-30	3,417,075	5.6%
Sands Capital Global Venture Fund II, L.P.	SCHEDULE 13G/A	2025-08-13	2025-06-30	1,146,173	1.9%
Sands Capital Life Sciences Pulse Fund, LLC	SCHEDULE 13G/A	2025-08-13	2025-06-30	1,146,173	1.9%
Sands Capital Ventures Discovery Fund III, L.P.	SCHEDULE 13G/A	2025-08-13	2025-06-30	1,124,729	1.9%
SANDS FRANK M.	SCHEDULE 13G/A	2025-08-13	2025-06-30	3,417,075	5.6%

Source: SEC Form 13F-HR information tables for the quarter ending 2026-06-30 (filed within 45 days of quarter end; amendments applied; values normalised to dollars), the share count from the company's latest 10-K/10-Q XBRL cover page, and Schedule 13D/13G filings. Each row is a legal 13F filer as filed — related entities (e.g. Vanguard's advisers) are not merged. Retail brokerage accounts are not reported on 13F, so the remainder is mostly retail and insiders.