ABOS US Equity

Acumen Pharmaceuticals, Inc.

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Health Care · Biological Products, (No Diagnostic Substances) · CIK 1576885 · FYE 1231

$2.28

+0.08 (+3.64%)

USD · as of 2026-07-28 · marketstack

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Institutional ownership· 13F filers holding ABOS · 2026-Q1 methodology → sources →

84 holders

% of shares outstanding held

63.7%

Shares held (13F)

46,001,105

Reporting holders

Top holders

largest 84 of 84 · Δ vs 2025-Q4

#	Holder	Shares	Value	% of shares out	Δ QoQ
1	RA CAPITAL MANAGEMENT, L.P.	20,992,66921.0M	$50M	29.06%	ADD 41%
2	Sands Capital Alternatives, LLC	3,720,1053.7M	$9M	5.15%	ADD 9%
3	Alyeska Investment Group, L.P.	2,454,7542.5M	$6M	3.40%	ADD 161%
4	FRANKLIN RESOURCES INC	2,305,0962.3M	$5M	3.19%	—
5	ADAR1 Capital Management, LLC	2,156,3342.2M	$5M	2.99%	ADD 142%
6	Knollwood Investment Advisory, LLC	1,628,5101.6M	$4M	2.25%	—
7	VANGUARD CAPITAL MANAGEMENT LLC	1,506,2771.5M	$4M	2.09%	NEW†
8	FMR LLC	1,157,3461.2M	$3M	1.60%	TRIM -43%
9	Ikarian Capital, LLC	1,053,7971.1M	$2M	1.46%	ADD 314%
10	Hudson Bay Capital Management LP	968,940968,940	$2M	1.34%	ADD 34%
11	Pathstone Holdings, LLC	859,110859,110	$2M	1.19%	—
12	SG Americas Securities, LLC	719,257719,257	$2M	1.00%	ADD 79%
13	MILLENNIUM MANAGEMENT LLC	659,675659,675	$2M	0.91%	ADD 13%
14	SUSQUEHANNA INTERNATIONAL GROUP, LLP	601,476601,476	$1M	0.83%	ADD 61%
15	TWO SIGMA INVESTMENTS, LP	530,812530,812	$1M	0.73%	ADD 271%
16	Laurion Capital Management LP	525,444525,444	$1M	0.73%	TRIM -39%
17	RENAISSANCE TECHNOLOGIES LLC	473,946473,946	$1M	0.66%	ADD 12%
18	GEODE CAPITAL MANAGEMENT, LLC	416,238416,238	$982,755	0.58%	—
19	BANK OF AMERICA CORP /DE/	320,216320,216	$755,710	0.44%	ADD 33%
20	BOOTHBAY FUND MANAGEMENT, LLC	273,012273,012	$644,308	0.38%	ADD 590%
21	GOLDMAN SACHS GROUP INC	206,683206,683	$487,772	0.29%	ADD 75%
22	VANGUARD FIDUCIARY TRUST CO	199,226199,226	$470,173	0.28%	NEW
23	MARSHALL WACE, LLP	192,889192,889	$455,218	0.27%	ADD 823%
24	ACADIAN ASSET MANAGEMENT LLC	185,850185,850	$435,000	0.26%	ADD 22%
25	BlackRock, Inc.	178,326178,326	$420,849	0.25%	ADD 5%
26	BRIDGEWAY CAPITAL MANAGEMENT, LLC	176,171176,171	$415,764	0.24%	ADD 4%
27	STATE STREET CORP	151,728151,728	$358,078	0.21%	ADD 51%
28	MORGAN STANLEY	144,584144,584	$341,219	0.20%	TRIM -13%
29	Qube Research & Technologies Ltd	120,388120,388	$284,116	0.17%	ADD 151%
30	DIMENSIONAL FUND ADVISORS LP	119,756119,756	$281,763	0.17%	ADD 144%
31	CATALYST FINANCIAL PARTNERS LLC	89,69989,699	$211,690	0.12%	—
32	JANE STREET GROUP, LLC	89,66189,661	$211,599	0.12%	TRIM -37%
33	PFG Investments, LLC	80,85080,850	$190,806	0.11%	ADD 326%
34	NORTHERN TRUST CORP	75,21275,212	$177,500	0.10%	—
35	Point72 Asset Management, L.P.	67,37567,375	$159,005	0.09%	ADD 85%
36	Prospera Financial Services Inc	50,00050,000	$118,000	0.07%	—
37	Catalyst Funds Management Pty Ltd	45,60045,600	$107,616	0.06%	ADD 54%
38	Verdad Advisers, LP	37,27837,278	$87,976	0.05%	NEW
39	UBS Group AG	37,14637,146	$87,665	0.05%	ADD 72%
40	Rangeley Capital, LLC	35,00035,000	$82,600	0.05%	NEW
41	BARCLAYS PLC	30,67930,679	$72,402	0.04%	ADD 2%
42	Intrepid Financial Planning Group LLC	30,15030,150	$71,154	0.04%	—
43	OMERS ADMINISTRATION Corp	28,60028,600	$67,496	0.04%	ADD 27%
44	AXQ CAPITAL, LP	28,48728,487	$67,229	0.04%	NEW
45	Independent Advisor Alliance	19,00019,000	$44,840	0.03%	—
46	PINNACLE ASSOCIATES LTD	18,02018,020	$42,527	0.02%	—
47	Pinnacle Wealth Management Advisory Group, LLC	18,02018,020	$42,527	0.02%	—
48	AMERICAN CENTURY COMPANIES INC	17,92917,929	$42,312	0.02%	NEW
49	SIMPLEX TRADING, LLC	17,41417,414	$41,097	0.02%	NEW
50	Factor Wealth Management LTD	16,50016,500	$38,940	0.02%	—
51	CAPTRUST FINANCIAL ADVISORS	15,75715,757	$37,187	0.02%	NEW
52	Brevan Howard Capital Management LP	15,38515,385	$36,309	0.02%	NEW
53	Squarepoint Ops LLC	15,01515,015	$35,435	0.02%	NEW
54	HRT FINANCIAL LP	13,16213,162	$31,000	0.02%	NEW
55	JACOBS LEVY EQUITY MANAGEMENT, INC	13,01113,011	$30,706	0.02%	NEW
56	SEI INVESTMENTS CO	11,56411,564	$27,291	0.02%	NEW
57	Mesirow Financial Investment Management, Inc.	11,30511,305	$26,680	0.02%	NEW
58	Schonfeld Strategic Advisors LLC	11,30011,300	$26,668	0.02%	NEW
59	Integrated Wealth Concepts LLC	10,17910,179	$24,022	0.01%	NEW
60	WELLS FARGO & COMPANY/MN	10,10810,108	$23,855	0.01%	ADD 42%
61	ROYAL BANK OF CANADA	7,0907,090	$17,000	0.01%	ADD 211%
62	Vanguard Global Advisers, LLC	6,6846,684	$15,774	0.01%	NEW
63	OSAIC HOLDINGS, INC.	5,3515,351	$12,628	0.01%	TRIM -22%
64	CITIGROUP INC	4,4864,486	$10,587	0.01%	NEW
65	PNC FINANCIAL SERVICES GROUP, INC.	3,0803,080	$7,269	0.00%	—
66	Rockefeller Capital Management L.P.	3,0003,000	$7,080	0.00%	—
67	TFC Financial Management, Inc.	2,5002,500	$5,900	0.00%	—
68	JONES FINANCIAL COMPANIES LLLP	2,0002,000	$4,520	0.00%	NEW
69	GROUP ONE TRADING LLC	1,4751,475	$3,481	0.00%	TRIM -69%
70	JPMORGAN CHASE & CO	1,4441,444	$3,162	0.00%	TRIM -40%
71	NISA INVESTMENT ADVISORS, LLC	1,2291,229	$2,900	0.00%	—
72	BNP PARIBAS FINANCIAL MARKETS	1,2081,208	$2,851	0.00%	—
73	Advisory Services Network, LLC	1,1111,111	$2,622	0.00%	NEW
74	US BANCORP \DE\	1,0001,000	$2,360	0.00%	NEW
75	EverSource Wealth Advisors, LLC	407407	$961	0.00%	—
76	SBI Securities Co., Ltd.	303303	$715	0.00%	TRIM -6%
77	Farther Finance Advisors, LLC	200200	$510	0.00%	—
78	NBT BANK N A /NY	200200	$472	0.00%	ADD 9900%
79	Tower Research Capital LLC (TRC)	118118	$278	0.00%	TRIM -97%
80	CWM, LLC	8787	$205	0.00%	TRIM -41%
81	Clearstead Advisors, LLC	6060	$142	0.00%	—
82	Arax Advisory Partners	2626	$61	0.00%	—
83	Larson Financial Group LLC	2020	$47	0.00%	TRIM -100%
84	Optiver Holding B.V.	55	$12	0.00%	—

† a filer this large appearing as NEW usually reflects a renamed or succeeded filing entity (the old name stops filing the same quarter) — not a brand-new position.

Rows rank by the value each filer reported — 13F filers price their own positions, so a holder with fewer shares can rank just above one with more.

Holder trends· top 15 holders · shares held over 6 quarters

green added · red trimmed

Holder

2024-Q4

2025-Q1

2025-Q2

2025-Q3

2025-Q4

2026-Q1

Latest value

RA CAPITAL MANAGEMENT, L.P.

14.9M

21.0M

$50M

Sands Capital Alternatives, LLC

3.4M

3.7M

$9M

Alyeska Investment Group, L.P.

940K

2.5M

$6M

FRANKLIN RESOURCES INC

3.3M

3.1M

2.3M

$5M

ADAR1 Capital Management, LLC

94K

146K

916K

891K

2.2M

$5M

Knollwood Investment Advisory, LLC

1.6M

$4M

VANGUARD CAPITAL MANAGEMENT LLC

—

1.5M

$4M

FMR LLC

2.0M

1.2M

$3M

Ikarian Capital, LLC

266K

254K

1.1M

$2M

Hudson Bay Capital Management LP

715K

770K

825K

725K

969K

$2M

Pathstone Holdings, LLC

607K

1.1M

859K

$2M

SG Americas Securities, LLC

26K

18K

—

404K

401K

719K

$2M

MILLENNIUM MANAGEMENT LLC

1.3M

1.1M

2.0M

602K

584K

660K

$2M

SUSQUEHANNA INTERNATIONAL GROUP, LLP

76K

111K

152K

214K

373K

601K

$1M

TWO SIGMA INVESTMENTS, LP

301K

232K

201K

199K

143K

531K

$1M

Shares reported each quarter by the largest current holders. Green = added vs the prior filing, red = trimmed, grey = roughly held; a dash is a quarter with no 13F on file (a gap is skipped, not read as an exit). 13F is filed up to 45 days after quarter-end. Up to 40 quarters (10 years) available — use the selector above.

Institutional footprint by quarter

Line breaks are honest gaps — quarters with no 13F record, or a suppressed % — never interpolated. % of shares outstanding uses today's share count for every quarter (the only count stored).

Quarter	Holders	Shares held	% shares out	Value held
2026-Q1	84	46,001,105	63.7%	$109M
2025-Q4	71	35,659,962	49.4%	$75M
2025-Q3	69	35,735,795	49.5%	$61M
2025-Q2	71	37,614,822	52.1%	$44M
2025-Q1	81	40,269,403	55.8%	$45M
2024-Q4	80	42,532,930	58.9%	$73M
2024-Q3	73	43,668,500	60.5%	$108M
2024-Q2	81	43,599,174	60.4%	$106M
2024-Q1	80	43,535,492	60.3%	$176M
2023-Q4	67	38,498,181	53.3%	$148M
2023-Q3	66	43,711,828	60.5%

Short interest has its own tab now — open SI →

Source: SEC Form 13F — every institution manager (≥ $100M in 13F securities) reporting a long US-listed position, across ~10,250 filers over 10 years of history. 13F is long-only, US-listed, filed up to 45 days after quarter-end.

Institutional ownership· 13F filers holding ABOS · 2026-Q1 methodology → sources →

84 holders

% of shares outstanding held

63.7%

Shares held (13F)

46,001,105

Reporting holders

Top holders

largest 84 of 84 · Δ vs 2025-Q4

#	Holder	Shares	Value	% of shares out	Δ QoQ
1	RA CAPITAL MANAGEMENT, L.P.	20,992,66921.0M	$50M	29.06%	ADD 41%
2	Sands Capital Alternatives, LLC	3,720,1053.7M	$9M	5.15%	ADD 9%
3	Alyeska Investment Group, L.P.	2,454,7542.5M	$6M	3.40%	ADD 161%
4	FRANKLIN RESOURCES INC	2,305,0962.3M	$5M	3.19%	—
5	ADAR1 Capital Management, LLC	2,156,3342.2M	$5M	2.99%	ADD 142%
6	Knollwood Investment Advisory, LLC	1,628,5101.6M	$4M	2.25%	—
7	VANGUARD CAPITAL MANAGEMENT LLC	1,506,2771.5M	$4M	2.09%	NEW†
8	FMR LLC	1,157,3461.2M	$3M	1.60%	TRIM -43%
9	Ikarian Capital, LLC	1,053,7971.1M	$2M	1.46%	ADD 314%
10	Hudson Bay Capital Management LP	968,940968,940	$2M	1.34%	ADD 34%
11	Pathstone Holdings, LLC	859,110859,110	$2M	1.19%	—
12	SG Americas Securities, LLC	719,257719,257	$2M	1.00%	ADD 79%
13	MILLENNIUM MANAGEMENT LLC	659,675659,675	$2M	0.91%	ADD 13%
14	SUSQUEHANNA INTERNATIONAL GROUP, LLP	601,476601,476	$1M	0.83%	ADD 61%
15	TWO SIGMA INVESTMENTS, LP	530,812530,812	$1M	0.73%	ADD 271%
16	Laurion Capital Management LP	525,444525,444	$1M	0.73%	TRIM -39%
17	RENAISSANCE TECHNOLOGIES LLC	473,946473,946	$1M	0.66%	ADD 12%
18	GEODE CAPITAL MANAGEMENT, LLC	416,238416,238	$982,755	0.58%	—
19	BANK OF AMERICA CORP /DE/	320,216320,216	$755,710	0.44%	ADD 33%
20	BOOTHBAY FUND MANAGEMENT, LLC	273,012273,012	$644,308	0.38%	ADD 590%
21	GOLDMAN SACHS GROUP INC	206,683206,683	$487,772	0.29%	ADD 75%
22	VANGUARD FIDUCIARY TRUST CO	199,226199,226	$470,173	0.28%	NEW
23	MARSHALL WACE, LLP	192,889192,889	$455,218	0.27%	ADD 823%
24	ACADIAN ASSET MANAGEMENT LLC	185,850185,850	$435,000	0.26%	ADD 22%
25	BlackRock, Inc.	178,326178,326	$420,849	0.25%	ADD 5%
26	BRIDGEWAY CAPITAL MANAGEMENT, LLC	176,171176,171	$415,764	0.24%	ADD 4%
27	STATE STREET CORP	151,728151,728	$358,078	0.21%	ADD 51%
28	MORGAN STANLEY	144,584144,584	$341,219	0.20%	TRIM -13%
29	Qube Research & Technologies Ltd	120,388120,388	$284,116	0.17%	ADD 151%
30	DIMENSIONAL FUND ADVISORS LP	119,756119,756	$281,763	0.17%	ADD 144%
31	CATALYST FINANCIAL PARTNERS LLC	89,69989,699	$211,690	0.12%	—
32	JANE STREET GROUP, LLC	89,66189,661	$211,599	0.12%	TRIM -37%
33	PFG Investments, LLC	80,85080,850	$190,806	0.11%	ADD 326%
34	NORTHERN TRUST CORP	75,21275,212	$177,500	0.10%	—
35	Point72 Asset Management, L.P.	67,37567,375	$159,005	0.09%	ADD 85%
36	Prospera Financial Services Inc	50,00050,000	$118,000	0.07%	—
37	Catalyst Funds Management Pty Ltd	45,60045,600	$107,616	0.06%	ADD 54%
38	Verdad Advisers, LP	37,27837,278	$87,976	0.05%	NEW
39	UBS Group AG	37,14637,146	$87,665	0.05%	ADD 72%
40	Rangeley Capital, LLC	35,00035,000	$82,600	0.05%	NEW
41	BARCLAYS PLC	30,67930,679	$72,402	0.04%	ADD 2%
42	Intrepid Financial Planning Group LLC	30,15030,150	$71,154	0.04%	—
43	OMERS ADMINISTRATION Corp	28,60028,600	$67,496	0.04%	ADD 27%
44	AXQ CAPITAL, LP	28,48728,487	$67,229	0.04%	NEW
45	Independent Advisor Alliance	19,00019,000	$44,840	0.03%	—
46	PINNACLE ASSOCIATES LTD	18,02018,020	$42,527	0.02%	—
47	Pinnacle Wealth Management Advisory Group, LLC	18,02018,020	$42,527	0.02%	—
48	AMERICAN CENTURY COMPANIES INC	17,92917,929	$42,312	0.02%	NEW
49	SIMPLEX TRADING, LLC	17,41417,414	$41,097	0.02%	NEW
50	Factor Wealth Management LTD	16,50016,500	$38,940	0.02%	—
51	CAPTRUST FINANCIAL ADVISORS	15,75715,757	$37,187	0.02%	NEW
52	Brevan Howard Capital Management LP	15,38515,385	$36,309	0.02%	NEW
53	Squarepoint Ops LLC	15,01515,015	$35,435	0.02%	NEW
54	HRT FINANCIAL LP	13,16213,162	$31,000	0.02%	NEW
55	JACOBS LEVY EQUITY MANAGEMENT, INC	13,01113,011	$30,706	0.02%	NEW
56	SEI INVESTMENTS CO	11,56411,564	$27,291	0.02%	NEW
57	Mesirow Financial Investment Management, Inc.	11,30511,305	$26,680	0.02%	NEW
58	Schonfeld Strategic Advisors LLC	11,30011,300	$26,668	0.02%	NEW
59	Integrated Wealth Concepts LLC	10,17910,179	$24,022	0.01%	NEW
60	WELLS FARGO & COMPANY/MN	10,10810,108	$23,855	0.01%	ADD 42%
61	ROYAL BANK OF CANADA	7,0907,090	$17,000	0.01%	ADD 211%
62	Vanguard Global Advisers, LLC	6,6846,684	$15,774	0.01%	NEW
63	OSAIC HOLDINGS, INC.	5,3515,351	$12,628	0.01%	TRIM -22%
64	CITIGROUP INC	4,4864,486	$10,587	0.01%	NEW
65	PNC FINANCIAL SERVICES GROUP, INC.	3,0803,080	$7,269	0.00%	—
66	Rockefeller Capital Management L.P.	3,0003,000	$7,080	0.00%	—
67	TFC Financial Management, Inc.	2,5002,500	$5,900	0.00%	—
68	JONES FINANCIAL COMPANIES LLLP	2,0002,000	$4,520	0.00%	NEW
69	GROUP ONE TRADING LLC	1,4751,475	$3,481	0.00%	TRIM -69%
70	JPMORGAN CHASE & CO	1,4441,444	$3,162	0.00%	TRIM -40%
71	NISA INVESTMENT ADVISORS, LLC	1,2291,229	$2,900	0.00%	—
72	BNP PARIBAS FINANCIAL MARKETS	1,2081,208	$2,851	0.00%	—
73	Advisory Services Network, LLC	1,1111,111	$2,622	0.00%	NEW
74	US BANCORP \DE\	1,0001,000	$2,360	0.00%	NEW
75	EverSource Wealth Advisors, LLC	407407	$961	0.00%	—
76	SBI Securities Co., Ltd.	303303	$715	0.00%	TRIM -6%
77	Farther Finance Advisors, LLC	200200	$510	0.00%	—
78	NBT BANK N A /NY	200200	$472	0.00%	ADD 9900%
79	Tower Research Capital LLC (TRC)	118118	$278	0.00%	TRIM -97%
80	CWM, LLC	8787	$205	0.00%	TRIM -41%
81	Clearstead Advisors, LLC	6060	$142	0.00%	—
82	Arax Advisory Partners	2626	$61	0.00%	—
83	Larson Financial Group LLC	2020	$47	0.00%	TRIM -100%
84	Optiver Holding B.V.	55	$12	0.00%	—

† a filer this large appearing as NEW usually reflects a renamed or succeeded filing entity (the old name stops filing the same quarter) — not a brand-new position.

Rows rank by the value each filer reported — 13F filers price their own positions, so a holder with fewer shares can rank just above one with more.

Holder trends· top 15 holders · shares held over 6 quarters

green added · red trimmed

Holder

2024-Q4

2025-Q1

2025-Q2

2025-Q3

2025-Q4

2026-Q1

Latest value

RA CAPITAL MANAGEMENT, L.P.

14.9M

21.0M

$50M

Sands Capital Alternatives, LLC

3.4M

3.7M

$9M

Alyeska Investment Group, L.P.

940K

2.5M

$6M

FRANKLIN RESOURCES INC

3.3M

3.1M

2.3M

$5M

ADAR1 Capital Management, LLC

94K

146K

916K

891K

2.2M

$5M

Knollwood Investment Advisory, LLC

1.6M

$4M

VANGUARD CAPITAL MANAGEMENT LLC

—

1.5M

$4M

FMR LLC

2.0M

1.2M

$3M

Ikarian Capital, LLC

266K

254K

1.1M

$2M

Hudson Bay Capital Management LP

715K

770K

825K

725K

969K

$2M

Pathstone Holdings, LLC

607K

1.1M

859K

$2M

SG Americas Securities, LLC

26K

18K

—

404K

401K

719K

$2M

MILLENNIUM MANAGEMENT LLC

1.3M

1.1M

2.0M

602K

584K

660K

$2M

SUSQUEHANNA INTERNATIONAL GROUP, LLP

76K

111K

152K

214K

373K

601K

$1M

TWO SIGMA INVESTMENTS, LP

301K

232K

201K

199K

143K

531K

$1M

Institutional footprint by quarter

Line breaks are honest gaps — quarters with no 13F record, or a suppressed % — never interpolated. % of shares outstanding uses today's share count for every quarter (the only count stored).

Quarter	Holders	Shares held	% shares out	Value held
2026-Q1	84	46,001,105	63.7%	$109M
2025-Q4	71	35,659,962	49.4%	$75M
2025-Q3	69	35,735,795	49.5%	$61M
2025-Q2	71	37,614,822	52.1%	$44M
2025-Q1	81	40,269,403	55.8%	$45M
2024-Q4	80	42,532,930	58.9%	$73M
2024-Q3	73	43,668,500	60.5%	$108M
2024-Q2	81	43,599,174	60.4%	$106M
2024-Q1	80	43,535,492	60.3%	$176M
2023-Q4	67	38,498,181	53.3%	$148M
2023-Q3	66	43,711,828	60.5%

Short interest has its own tab now — open SI →

ABOS US Equity☆

Institutional ownership· 13F filers holding ABOS · 2026-Q1 methodology → sources →

Top holders

Holder trends· top 15 holders · shares held over 6 quarters

Institutional footprint by quarter

Institutional ownership· 13F filers holding ABOS · 2026-Q1 methodology → sources →

Top holders

Holder trends· top 15 holders · shares held over 6 quarters

Institutional footprint by quarter

ABOS US Equity