ATRC US Equity

AtriCure, Inc.

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Health Care · Surgical & Medical Instruments & Apparatus · CIK 1323885 · FYE 1231

$40.89

+1.14 (+2.87%)

USD · as of 2026-07-29 · marketstack

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

222 holders

% of shares outstanding held

98.3%

Shares held (13F)

50,013,371

Reporting holders

222

Top holders

largest 100 of 222 · Δ vs 2025-Q4

#	Holder	Shares	Value	% of shares out	Δ QoQ
1	ALLIANCEBERNSTEIN L.P.	3,258,8723.3M	$129M	6.41%	TRIM -9%
2	BlackRock, Inc.	4,042,6814.0M	$115M	7.95%	—
3	WELLINGTON MANAGEMENT GROUP LLP	3,382,5553.4M	$97M	6.65%	TRIM -14%
4	Hood River Capital Management LLC	3,117,5453.1M	$89M	6.13%	—
5	VANGUARD PORTFOLIO MANAGEMENT LLC	2,702,6322.7M	$77M	5.31%	NEW†
6	VANGUARD CAPITAL MANAGEMENT LLC	2,155,7642.2M	$62M	4.24%	NEW†
7	NOMURA ASSET MANAGEMENT INTERNATIONAL INC.	1,804,9271.8M	$51M	3.55%	TRIM -11%
8	GOLDMAN SACHS GROUP INC	1,667,1661.7M	$48M	3.28%	ADD 88%
9	MARSHALL WACE, LLP	1,467,5241.5M	$42M	2.89%	ADD 61%
10	STATE STREET CORP	1,302,1621.3M	$37M	2.56%	ADD 5%
11	GEODE CAPITAL MANAGEMENT, LLC	1,226,1161.2M	$35M	2.41%	ADD 3%
12	Divisadero Street Capital Management, LP	1,159,9551.2M	$33M	2.28%	NEW†
13	BNP PARIBAS ASSET MANAGEMENT Holding S.A.	1,060,8061.1M	$30M	2.09%	ADD 11%
14	NEUBERGER BERMAN GROUP LLC	1,050,2821.1M	$30M	2.06%	TRIM -3%
15	DIMENSIONAL FUND ADVISORS LP	997,759997,759	$28M	1.96%	ADD 8%
16	Champlain Investment Partners, LLC	971,111971,111	$28M	1.91%	TRIM -17%
17	GW&K Investment Management, LLC	963,415963,415	$27M	1.89%	—
18	KENNEDY CAPITAL MANAGEMENT LLC	834,155834,155	$24M	1.64%	—
19	BANK OF AMERICA CORP /DE/	768,561768,561	$22M	1.51%	ADD 14%
20	TWO SIGMA INVESTMENTS, LP	751,003751,003	$21M	1.48%	ADD 97%
21	First Light Asset Management, LLC	729,521729,521	$21M	1.43%	TRIM -38%
22	VOYA INVESTMENT MANAGEMENT LLC	719,649719,649	$21M	1.41%	—
23	MORGAN STANLEY	719,162719,162	$21M	1.41%	ADD 108%
24	DAFNA Capital Management LLC	597,431597,431	$17M	1.17%	—
25	MASSACHUSETTS FINANCIAL SERVICES CO /MA/	585,353585,353	$17M	1.15%	ADD 15%
26	UBS AM, a distinct business unit of UBS ASSET MANAGEMENT AMERICAS LLC	555,114555,114	$16M	1.09%	TRIM -3%
27	Qube Research & Technologies Ltd	454,791454,791	$13M	0.89%	ADD 57%
28	NORTHERN TRUST CORP	449,599449,599	$13M	0.88%	ADD 3%
29	CHARLES SCHWAB INVESTMENT MANAGEMENT INC	429,833429,833	$12M	0.85%	—
30	Grandeur Peak Global Advisors, LLC	381,902381,902	$11M	0.75%	ADD 16%
31	WCM INVESTMENT MANAGEMENT, LLC	359,761359,761	$10M	0.71%	TRIM -3%
32	OSTERWEIS CAPITAL MANAGEMENT INC	349,645349,645	$10M	0.69%	ADD 72%
33	Connor, Clark & Lunn Investment Management Ltd.	345,388345,388	$10M	0.68%	TRIM -9%
34	VANGUARD FIDUCIARY TRUST CO	342,854342,854	$10M	0.67%	NEW
35	FMR LLC	336,814336,814	$10M	0.66%	ADD 18%
36	Nuveen, LLC	336,727336,727	$10M	0.66%	—
37	RENAISSANCE TECHNOLOGIES LLC	308,700308,700	$9M	0.61%	TRIM -4%
38	ARROWSTREET CAPITAL, LIMITED PARTNERSHIP	277,682277,682	$8M	0.55%	NEW
39	First Eagle Investment Management, LLC	262,143262,143	$7M	0.52%	ADD 125%
40	SEI INVESTMENTS CO	260,788260,788	$7M	0.51%	ADD 65%
41	WASATCH ADVISORS LP	253,931253,931	$7M	0.50%	TRIM -28%
42	PANAGORA ASSET MANAGEMENT INC	227,377227,377	$6M	0.45%	—
43	Amundi	225,932225,932	$6M	0.44%	TRIM -2%
44	Universal- Beteiligungs- und Servicegesellschaft mbH	215,545215,545	$6M	0.42%	ADD 12%
45	RAYMOND JAMES FINANCIAL INC	216,907216,907	$6M	0.43%	—
46	NICHOLAS COMPANY, INC.	204,595204,595	$6M	0.40%	—
47	FIRST TRUST ADVISORS LP	189,285189,285	$5M	0.37%	ADD 61%
48	AQR CAPITAL MANAGEMENT LLC	186,382186,382	$5M	0.37%	ADD 86%
49	Advisors Capital Management, LLC	182,314182,314	$5M	0.36%	—
50	MILLENNIUM MANAGEMENT LLC	179,886179,886	$5M	0.35%	ADD 10%
51	JPMORGAN CHASE & CO	171,263171,263	$5M	0.34%	TRIM -5%
52	STATE OF WISCONSIN INVESTMENT BOARD	167,354167,354	$5M	0.33%	—
53	ADAGE CAPITAL PARTNERS GP, L.L.C.	150,000150,000	$4M	0.29%	ADD 36%
54	Trexquant Investment LP	143,094143,094	$4M	0.28%	ADD 84%
55	Bank of New York Mellon Corp	130,650130,650	$4M	0.26%	TRIM -4%
56	PARADIGM CAPITAL MANAGEMENT INC/NY	123,100123,100	$4M	0.24%	—
57	Allianz Asset Management GmbH	122,158122,158	$3M	0.24%	ADD 4%
58	SIT INVESTMENT ASSOCIATES INC	113,330113,330	$3M	0.22%	ADD 5%
59	Schonfeld Strategic Advisors LLC	101,682101,682	$3M	0.20%	NEW
60	Swiss National Bank	98,00098,000	$3M	0.19%	—
61	VOLORIDGE INVESTMENT MANAGEMENT, LLC	97,18297,182	$3M	0.19%	TRIM -56%
62	ACADIAN ASSET MANAGEMENT LLC	88,85288,852	$3M	0.17%	ADD 7%
63	CITADEL ADVISORS LLC	87,34787,347	$2M	0.17%	TRIM -64%
64	Man Group plc	85,11685,116	$2M	0.17%	ADD 389%
65	HighMark Wealth Management LLC	83,72083,720	$2M	0.16%	—
66	Invesco Ltd.	77,31677,316	$2M	0.15%	ADD 4%
67	Emerald Investment Advisers, LLC	71,49271,492	$2M	0.14%	NEW
68	Riverwater Partners LLC	70,50670,506	$2M	0.14%	ADD 17%
69	WELLS FARGO & COMPANY/MN	69,08469,084	$2M	0.14%	TRIM -32%
70	HRT FINANCIAL LP	67,07167,071	$2M	0.13%	NEW
71	RHUMBLINE ADVISERS	66,28166,281	$2M	0.13%	—
72	UBS Group AG	65,86565,865	$2M	0.13%	TRIM -37%
73	PRINCIPAL FINANCIAL GROUP INC	64,29664,296	$2M	0.13%	ADD 46%
74	PRICE T ROWE ASSOCIATES INC /MD/	60,28560,285	$2M	0.12%	ADD 19%
75	CALIFORNIA STATE TEACHERS RETIREMENT SYSTEM	59,94759,947	$2M	0.12%	ADD 33%
76	Orion Porfolio Solutions, LLC	58,29758,297	$2M	0.11%	TRIM -3%
77	ENVESTNET ASSET MANAGEMENT INC	57,87757,877	$2M	0.11%	—
78	D. E. Shaw & Co., Inc.	56,58956,589	$2M	0.11%	NEW
79	FRANKLIN RESOURCES INC	55,51655,516	$2M	0.11%	ADD 6%
80	LAZARD ASSET MANAGEMENT LLC	54,01554,015	$2M	0.11%	ADD 9%
81	AMERIPRISE FINANCIAL INC	52,38352,383	$1M	0.10%	ADD 95%
82	Knott David M Jr	51,40051,400	$1M	0.10%	—
83	DEUTSCHE BANK AG\	50,51050,510	$1M	0.10%	ADD 10%
84	B. Metzler seel. Sohn & Co. AG	49,87649,876	$1M	0.10%	—
85	Oak Harvest Investment Services	45,00045,000	$1M	0.09%	ADD 20%
86	VANGUARD ASSET MANAGEMENT, Ltd	44,78444,784	$1M	0.09%	NEW
87	Engineers Gate Manager LP	42,87742,877	$1M	0.08%	TRIM -27%
88	Legal & General Group Plc	42,30242,302	$1M	0.08%	TRIM -19%
89	HARBOR CAPITAL ADVISORS, INC.	41,54741,547	$1M	0.08%	ADD 24%
90	ALGERT GLOBAL LLC	40,79940,799	$1M	0.08%	TRIM -84%
91	SCOTIA CAPITAL INC.	40,37940,379	$1M	0.08%	ADD 4%
92	Diversified Trust Co	40,09040,090	$1M	0.08%	ADD 7%
93	SUSQUEHANNA INTERNATIONAL GROUP, LLP	38,77738,777	$1M	0.08%	NEW
94	GSA CAPITAL PARTNERS LLP	36,24236,242	$1M	0.07%	ADD 4%
95	TEACHERS RETIREMENT SYSTEM OF THE STATE OF KENTUCKY	36,10236,102	$1M	0.07%	—
96	Bridgewater Associates, LP	33,51733,517	$956,240	0.07%	NEW
97	PRUDENTIAL FINANCIAL INC	30,27030,270	$863,603	0.06%	TRIM -50%
98	Marks Group Wealth Management, Inc	28,97328,973	$826,600	0.06%	—
99	US BANCORP \DE\	28,10528,105	$801,836	0.06%	ADD 51%
100	MetLife Investment Management, LLC	26,71726,717	$762,236	0.05%	—

† 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

ALLIANCEBERNSTEIN L.P.

3.8M

3.7M

3.6M

3.3M

$129M

BlackRock, Inc.

4.3M

4.2M

4.0M

4.1M

4.0M

$115M

WELLINGTON MANAGEMENT GROUP LLP

655K

702K

4.0M

4.3M

3.9M

3.4M

$97M

Hood River Capital Management LLC

2.9M

3.0M

3.1M

3.0M

3.1M

$89M

VANGUARD PORTFOLIO MANAGEMENT LLC

—

2.7M

$77M

VANGUARD CAPITAL MANAGEMENT LLC

—

2.2M

$62M

NOMURA ASSET MANAGEMENT INTERNATIONAL INC.

—

2.0M

1.8M

$51M

GOLDMAN SACHS GROUP INC

854K

863K

745K

777K

885K

1.7M

$48M

MARSHALL WACE, LLP

619K

994K

1.0M

559K

913K

1.5M

$42M

STATE STREET CORP

1.3M

1.2M

1.3M

$37M

GEODE CAPITAL MANAGEMENT, LLC

1.2M

$35M

Divisadero Street Capital Management, LP

213K

34K

—

1.2M

$33M

BNP PARIBAS ASSET MANAGEMENT Holding S.A.

601K

748K

756K

767K

959K

1.1M

$30M

NEUBERGER BERMAN GROUP LLC

939K

1.2M

1.1M

$30M

DIMENSIONAL FUND ADVISORS LP

700K

711K

820K

851K

922K

998K

$28M

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	222	50,013,371	98.3%	$1.5B
2025-Q4

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.

Activists & large holders· Schedule 13D/G beneficial owners · ATRC

Large holders — 13G, passive (top 5 of 8 by % of class)

Holder

% of class

Type

As of

BlackRock, Inc.

7.8%

QII

2025-09-30

SEC →

WELLINGTON MANAGEMENT GROUP LLP

6.8%

QII

2026-03-31

SEC →

Hood River Capital Management LLC

6.23%

QII

2025-12-31

SEC →

VANGUARD PORTFOLIO MANAGEMENT LLC

5.51%

QII

2026-03-31

SEC →

VANGUARD CAPITAL MANAGEMENT LLC

5.08%

QII

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

222 holders

% of shares outstanding held

98.3%

Shares held (13F)

50,013,371

Reporting holders

222

Top holders

largest 100 of 222 · Δ vs 2025-Q4

#	Holder	Shares	Value	% of shares out	Δ QoQ
1	ALLIANCEBERNSTEIN L.P.	3,258,8723.3M	$129M	6.41%	TRIM -9%
2	BlackRock, Inc.	4,042,6814.0M	$115M	7.95%	—
3	WELLINGTON MANAGEMENT GROUP LLP	3,382,5553.4M	$97M	6.65%	TRIM -14%
4	Hood River Capital Management LLC	3,117,5453.1M	$89M	6.13%	—
5	VANGUARD PORTFOLIO MANAGEMENT LLC	2,702,6322.7M	$77M	5.31%	NEW†
6	VANGUARD CAPITAL MANAGEMENT LLC	2,155,7642.2M	$62M	4.24%	NEW†
7	NOMURA ASSET MANAGEMENT INTERNATIONAL INC.	1,804,9271.8M	$51M	3.55%	TRIM -11%
8	GOLDMAN SACHS GROUP INC	1,667,1661.7M	$48M	3.28%	ADD 88%
9	MARSHALL WACE, LLP	1,467,5241.5M	$42M	2.89%	ADD 61%
10	STATE STREET CORP	1,302,1621.3M	$37M	2.56%	ADD 5%
11	GEODE CAPITAL MANAGEMENT, LLC	1,226,1161.2M	$35M	2.41%	ADD 3%
12	Divisadero Street Capital Management, LP	1,159,9551.2M	$33M	2.28%	NEW†
13	BNP PARIBAS ASSET MANAGEMENT Holding S.A.	1,060,8061.1M	$30M	2.09%	ADD 11%
14	NEUBERGER BERMAN GROUP LLC	1,050,2821.1M	$30M	2.06%	TRIM -3%
15	DIMENSIONAL FUND ADVISORS LP	997,759997,759	$28M	1.96%	ADD 8%
16	Champlain Investment Partners, LLC	971,111971,111	$28M	1.91%	TRIM -17%
17	GW&K Investment Management, LLC	963,415963,415	$27M	1.89%	—
18	KENNEDY CAPITAL MANAGEMENT LLC	834,155834,155	$24M	1.64%	—
19	BANK OF AMERICA CORP /DE/	768,561768,561	$22M	1.51%	ADD 14%
20	TWO SIGMA INVESTMENTS, LP	751,003751,003	$21M	1.48%	ADD 97%
21	First Light Asset Management, LLC	729,521729,521	$21M	1.43%	TRIM -38%
22	VOYA INVESTMENT MANAGEMENT LLC	719,649719,649	$21M	1.41%	—
23	MORGAN STANLEY	719,162719,162	$21M	1.41%	ADD 108%
24	DAFNA Capital Management LLC	597,431597,431	$17M	1.17%	—
25	MASSACHUSETTS FINANCIAL SERVICES CO /MA/	585,353585,353	$17M	1.15%	ADD 15%
26	UBS AM, a distinct business unit of UBS ASSET MANAGEMENT AMERICAS LLC	555,114555,114	$16M	1.09%	TRIM -3%
27	Qube Research & Technologies Ltd	454,791454,791	$13M	0.89%	ADD 57%
28	NORTHERN TRUST CORP	449,599449,599	$13M	0.88%	ADD 3%
29	CHARLES SCHWAB INVESTMENT MANAGEMENT INC	429,833429,833	$12M	0.85%	—
30	Grandeur Peak Global Advisors, LLC	381,902381,902	$11M	0.75%	ADD 16%
31	WCM INVESTMENT MANAGEMENT, LLC	359,761359,761	$10M	0.71%	TRIM -3%
32	OSTERWEIS CAPITAL MANAGEMENT INC	349,645349,645	$10M	0.69%	ADD 72%
33	Connor, Clark & Lunn Investment Management Ltd.	345,388345,388	$10M	0.68%	TRIM -9%
34	VANGUARD FIDUCIARY TRUST CO	342,854342,854	$10M	0.67%	NEW
35	FMR LLC	336,814336,814	$10M	0.66%	ADD 18%
36	Nuveen, LLC	336,727336,727	$10M	0.66%	—
37	RENAISSANCE TECHNOLOGIES LLC	308,700308,700	$9M	0.61%	TRIM -4%
38	ARROWSTREET CAPITAL, LIMITED PARTNERSHIP	277,682277,682	$8M	0.55%	NEW
39	First Eagle Investment Management, LLC	262,143262,143	$7M	0.52%	ADD 125%
40	SEI INVESTMENTS CO	260,788260,788	$7M	0.51%	ADD 65%
41	WASATCH ADVISORS LP	253,931253,931	$7M	0.50%	TRIM -28%
42	PANAGORA ASSET MANAGEMENT INC	227,377227,377	$6M	0.45%	—
43	Amundi	225,932225,932	$6M	0.44%	TRIM -2%
44	Universal- Beteiligungs- und Servicegesellschaft mbH	215,545215,545	$6M	0.42%	ADD 12%
45	RAYMOND JAMES FINANCIAL INC	216,907216,907	$6M	0.43%	—
46	NICHOLAS COMPANY, INC.	204,595204,595	$6M	0.40%	—
47	FIRST TRUST ADVISORS LP	189,285189,285	$5M	0.37%	ADD 61%
48	AQR CAPITAL MANAGEMENT LLC	186,382186,382	$5M	0.37%	ADD 86%
49	Advisors Capital Management, LLC	182,314182,314	$5M	0.36%	—
50	MILLENNIUM MANAGEMENT LLC	179,886179,886	$5M	0.35%	ADD 10%
51	JPMORGAN CHASE & CO	171,263171,263	$5M	0.34%	TRIM -5%
52	STATE OF WISCONSIN INVESTMENT BOARD	167,354167,354	$5M	0.33%	—
53	ADAGE CAPITAL PARTNERS GP, L.L.C.	150,000150,000	$4M	0.29%	ADD 36%
54	Trexquant Investment LP	143,094143,094	$4M	0.28%	ADD 84%
55	Bank of New York Mellon Corp	130,650130,650	$4M	0.26%	TRIM -4%
56	PARADIGM CAPITAL MANAGEMENT INC/NY	123,100123,100	$4M	0.24%	—
57	Allianz Asset Management GmbH	122,158122,158	$3M	0.24%	ADD 4%
58	SIT INVESTMENT ASSOCIATES INC	113,330113,330	$3M	0.22%	ADD 5%
59	Schonfeld Strategic Advisors LLC	101,682101,682	$3M	0.20%	NEW
60	Swiss National Bank	98,00098,000	$3M	0.19%	—
61	VOLORIDGE INVESTMENT MANAGEMENT, LLC	97,18297,182	$3M	0.19%	TRIM -56%
62	ACADIAN ASSET MANAGEMENT LLC	88,85288,852	$3M	0.17%	ADD 7%
63	CITADEL ADVISORS LLC	87,34787,347	$2M	0.17%	TRIM -64%
64	Man Group plc	85,11685,116	$2M	0.17%	ADD 389%
65	HighMark Wealth Management LLC	83,72083,720	$2M	0.16%	—
66	Invesco Ltd.	77,31677,316	$2M	0.15%	ADD 4%
67	Emerald Investment Advisers, LLC	71,49271,492	$2M	0.14%	NEW
68	Riverwater Partners LLC	70,50670,506	$2M	0.14%	ADD 17%
69	WELLS FARGO & COMPANY/MN	69,08469,084	$2M	0.14%	TRIM -32%
70	HRT FINANCIAL LP	67,07167,071	$2M	0.13%	NEW
71	RHUMBLINE ADVISERS	66,28166,281	$2M	0.13%	—
72	UBS Group AG	65,86565,865	$2M	0.13%	TRIM -37%
73	PRINCIPAL FINANCIAL GROUP INC	64,29664,296	$2M	0.13%	ADD 46%
74	PRICE T ROWE ASSOCIATES INC /MD/	60,28560,285	$2M	0.12%	ADD 19%
75	CALIFORNIA STATE TEACHERS RETIREMENT SYSTEM	59,94759,947	$2M	0.12%	ADD 33%
76	Orion Porfolio Solutions, LLC	58,29758,297	$2M	0.11%	TRIM -3%
77	ENVESTNET ASSET MANAGEMENT INC	57,87757,877	$2M	0.11%	—
78	D. E. Shaw & Co., Inc.	56,58956,589	$2M	0.11%	NEW
79	FRANKLIN RESOURCES INC	55,51655,516	$2M	0.11%	ADD 6%
80	LAZARD ASSET MANAGEMENT LLC	54,01554,015	$2M	0.11%	ADD 9%
81	AMERIPRISE FINANCIAL INC	52,38352,383	$1M	0.10%	ADD 95%
82	Knott David M Jr	51,40051,400	$1M	0.10%	—
83	DEUTSCHE BANK AG\	50,51050,510	$1M	0.10%	ADD 10%
84	B. Metzler seel. Sohn & Co. AG	49,87649,876	$1M	0.10%	—
85	Oak Harvest Investment Services	45,00045,000	$1M	0.09%	ADD 20%
86	VANGUARD ASSET MANAGEMENT, Ltd	44,78444,784	$1M	0.09%	NEW
87	Engineers Gate Manager LP	42,87742,877	$1M	0.08%	TRIM -27%
88	Legal & General Group Plc	42,30242,302	$1M	0.08%	TRIM -19%
89	HARBOR CAPITAL ADVISORS, INC.	41,54741,547	$1M	0.08%	ADD 24%
90	ALGERT GLOBAL LLC	40,79940,799	$1M	0.08%	TRIM -84%
91	SCOTIA CAPITAL INC.	40,37940,379	$1M	0.08%	ADD 4%
92	Diversified Trust Co	40,09040,090	$1M	0.08%	ADD 7%
93	SUSQUEHANNA INTERNATIONAL GROUP, LLP	38,77738,777	$1M	0.08%	NEW
94	GSA CAPITAL PARTNERS LLP	36,24236,242	$1M	0.07%	ADD 4%
95	TEACHERS RETIREMENT SYSTEM OF THE STATE OF KENTUCKY	36,10236,102	$1M	0.07%	—
96	Bridgewater Associates, LP	33,51733,517	$956,240	0.07%	NEW
97	PRUDENTIAL FINANCIAL INC	30,27030,270	$863,603	0.06%	TRIM -50%
98	Marks Group Wealth Management, Inc	28,97328,973	$826,600	0.06%	—
99	US BANCORP \DE\	28,10528,105	$801,836	0.06%	ADD 51%
100	MetLife Investment Management, LLC	26,71726,717	$762,236	0.05%	—

† 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

ALLIANCEBERNSTEIN L.P.

3.8M

3.7M

3.6M

3.3M

$129M

BlackRock, Inc.

4.3M

4.2M

4.0M

4.1M

4.0M

$115M

WELLINGTON MANAGEMENT GROUP LLP

655K

702K

4.0M

4.3M

3.9M

3.4M

$97M

Hood River Capital Management LLC

2.9M

3.0M

3.1M

3.0M

3.1M

$89M

VANGUARD PORTFOLIO MANAGEMENT LLC

—

2.7M

$77M

VANGUARD CAPITAL MANAGEMENT LLC

—

2.2M

$62M

NOMURA ASSET MANAGEMENT INTERNATIONAL INC.

—

2.0M

1.8M

$51M

GOLDMAN SACHS GROUP INC

854K

863K

745K

777K

885K

1.7M

$48M

MARSHALL WACE, LLP

619K

994K

1.0M

559K

913K

1.5M

$42M

STATE STREET CORP

1.3M

1.2M

1.3M

$37M

GEODE CAPITAL MANAGEMENT, LLC

1.2M

$35M

Divisadero Street Capital Management, LP

213K

34K

—

1.2M

$33M

BNP PARIBAS ASSET MANAGEMENT Holding S.A.

601K

748K

756K

767K

959K

1.1M

$30M

NEUBERGER BERMAN GROUP LLC

939K

1.2M

1.1M

$30M

DIMENSIONAL FUND ADVISORS LP

700K

711K

820K

851K

922K

998K

$28M

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	222	50,013,371	98.3%	$1.5B
2025-Q4

Short interest has its own tab now — open SI →

Activists & large holders· Schedule 13D/G beneficial owners · ATRC

Large holders — 13G, passive (top 5 of 8 by % of class)

Holder

% of class

Type

As of

BlackRock, Inc.

7.8%

QII

2025-09-30

SEC →

WELLINGTON MANAGEMENT GROUP LLP

6.8%

QII

2026-03-31

SEC →

Hood River Capital Management LLC

6.23%

QII

2025-12-31

SEC →

VANGUARD PORTFOLIO MANAGEMENT LLC

5.51%

QII

2026-03-31

SEC →

VANGUARD CAPITAL MANAGEMENT LLC

5.08%

QII

ATRC US Equity☆

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

Top holders

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

Institutional footprint by quarter

Activists & large holders· Schedule 13D/G beneficial owners · ATRC

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

Top holders

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

Institutional footprint by quarter

Activists & large holders· Schedule 13D/G beneficial owners · ATRC

ATRC US Equity