AMPH US Equity

Amphastar Pharmaceuticals, Inc.

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Health Care · Pharmaceutical Preparations · CIK 1297184 · FYE 1231

$20.15

+0.97 (+5.06%)

USD · as of 2026-07-28 · marketstack

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

213 holders

% of shares outstanding held

72.8%

Shares held (13F)

32,081,025

Reporting holders

213

Top holders

largest 100 of 213 · Δ vs 2025-Q4

#	Holder	Shares	Value	% of shares out	Δ QoQ
1	BlackRock, Inc.	5,421,3435.4M	$106M	12.30%	—
2	DIMENSIONAL FUND ADVISORS LP	2,027,9472.0M	$40M	4.60%	ADD 13%
3	STATE STREET CORP	1,607,5151.6M	$31M	3.65%	ADD 5%
4	VANGUARD CAPITAL MANAGEMENT LLC	1,543,6551.5M	$30M	3.50%	NEW†
5	TD Asset Management Inc	1,541,0441.5M	$30M	3.49%	TRIM -21%
6	FULLER & THALER ASSET MANAGEMENT, INC.	1,395,1391.4M	$27M	3.16%	TRIM -50%
7	MARSHALL WACE, LLP	1,025,6401.0M	$20M	2.33%	TRIM -17%
8	AMERICAN CENTURY COMPANIES INC	1,017,5381.0M	$20M	2.31%	ADD 53%
9	GEODE CAPITAL MANAGEMENT, LLC	976,650976,650	$19M	2.21%	ADD 10%
10	Boston Trust Walden Corp	944,789944,789	$19M	2.14%	TRIM -13%
11	Epoch Investment Partners, Inc.	898,895898,895	$18M	2.04%	TRIM -20%
12	VANGUARD PORTFOLIO MANAGEMENT LLC	787,816787,816	$15M	1.79%	NEW
13	D. E. Shaw & Co., Inc.	665,542665,542	$13M	1.51%	ADD 19%
14	LSV ASSET MANAGEMENT	651,714651,714	$13M	1.48%	ADD 491%
15	Invesco Ltd.	604,774604,774	$12M	1.37%	ADD 21%
16	RENAISSANCE TECHNOLOGIES LLC	553,900553,900	$11M	1.26%	—
17	SYSTEMATIC FINANCIAL MANAGEMENT LP	452,898452,898	$9M	1.03%	ADD 4%
18	MORGAN STANLEY	420,337420,337	$8M	0.95%	TRIM -29%
19	UBS Group AG	420,263420,263	$8M	0.95%	ADD 64%
20	ROYCE & ASSOCIATES LP	406,175406,175	$8M	0.92%	ADD 15%
21	NORTHERN TRUST CORP	372,279372,279	$7M	0.84%	—
22	MILLENNIUM MANAGEMENT LLC	371,373371,373	$7M	0.84%	ADD 28%
23	Bridge City Capital, LLC	335,105335,105	$7M	0.76%	ADD 42%
24	BRIDGEWAY CAPITAL MANAGEMENT, LLC	330,457330,457	$6M	0.75%	ADD 2%
25	GOLDMAN SACHS GROUP INC	329,388329,388	$6M	0.75%	TRIM -41%
26	ARROWSTREET CAPITAL, LIMITED PARTNERSHIP	325,291325,291	$6M	0.74%	TRIM -42%
27	CHARLES SCHWAB INVESTMENT MANAGEMENT INC	321,039321,039	$6M	0.73%	TRIM -8%
28	DENALI ADVISORS LLC	266,465266,465	$5M	0.60%	ADD 26%
29	VICTORY CAPITAL MANAGEMENT INC	249,617249,617	$5M	0.57%	TRIM -18%
30	Bank of New York Mellon Corp	243,226243,226	$5M	0.55%	TRIM -6%
31	VANGUARD FIDUCIARY TRUST CO	231,044231,044	$5M	0.52%	NEW
32	PRINCIPAL FINANCIAL GROUP INC	209,131209,131	$4M	0.47%	TRIM -4%
33	RICE HALL JAMES & ASSOCIATES, LLC	187,348187,348	$4M	0.42%	ADD 55%
34	Empowered Funds, LLC	181,332181,332	$4M	0.41%	ADD 9%
35	BANK OF AMERICA CORP /DE/	174,323174,323	$3M	0.40%	ADD 36%
36	VOLORIDGE INVESTMENT MANAGEMENT, LLC	171,188171,188	$3M	0.39%	TRIM -26%
37	BNP PARIBAS FINANCIAL MARKETS	156,077156,077	$3M	0.35%	ADD 29%
38	FIRST TRUST ADVISORS LP	150,591150,591	$3M	0.34%	ADD 7%
39	NEW YORK STATE COMMON RETIREMENT FUND	148,722148,722	$3M	0.34%	ADD 18%
40	Universal- Beteiligungs- und Servicegesellschaft mbH	139,402139,402	$3M	0.32%	ADD 379%
41	FRANKLIN RESOURCES INC	139,305139,305	$3M	0.32%	ADD 435%
42	TWO SIGMA INVESTMENTS, LP	138,148138,148	$3M	0.31%	ADD 40%
43	LAM GROUP, INC.	130,800130,800	$3M	0.30%	—
44	Public Sector Pension Investment Board	126,574126,574	$2M	0.29%	ADD 3%
45	NORDEA INVESTMENT MANAGEMENT AB	123,824123,824	$2M	0.28%	TRIM -4%
46	BESSEMER GROUP INC	122,046122,046	$2M	0.28%	—
47	O'SHAUGHNESSY ASSET MANAGEMENT, LLC	103,929103,929	$2M	0.24%	ADD 19%
48	JPMORGAN CHASE & CO	104,574104,574	$2M	0.24%	TRIM -34%
49	JANE STREET GROUP, LLC	92,47592,475	$2M	0.21%	TRIM -57%
50	XTX Topco Ltd	87,73687,736	$2M	0.20%	ADD 81%
51	RHUMBLINE ADVISERS	83,72183,721	$2M	0.19%	—
52	EXCHANGE TRADED CONCEPTS, LLC	82,41682,416	$2M	0.19%	ADD 775%
53	Legal & General Group Plc	80,91680,916	$2M	0.18%	TRIM -11%
54	AQR CAPITAL MANAGEMENT LLC	78,77878,778	$2M	0.18%	ADD 16%
55	AMERIPRISE FINANCIAL INC	78,77578,775	$2M	0.18%	TRIM -41%
56	ALLIANCEBERNSTEIN L.P.	56,43056,430	$2M	0.13%	TRIM -7%
57	Nuveen, LLC	76,59576,595	$2M	0.17%	—
58	Swiss National Bank	72,60072,600	$1M	0.16%	—
59	Robeco Institutional Asset Management B.V.	66,40766,407	$1M	0.15%	NEW
60	CITADEL ADVISORS LLC	65,54065,540	$1M	0.15%	TRIM -71%
61	HUSSMAN STRATEGIC ADVISORS, INC.	63,00063,000	$1M	0.14%	NEW
62	ALGERT GLOBAL LLC	62,36062,360	$1M	0.14%	TRIM -50%
63	HRT FINANCIAL LP	56,18156,181	$1M	0.13%	NEW
64	UBS AM, a distinct business unit of UBS ASSET MANAGEMENT AMERICAS LLC	55,37555,375	$1M	0.13%	—
65	ASSETMARK, INC	53,73853,738	$1M	0.12%	—
66	PRUDENTIAL FINANCIAL INC	50,69350,693	$993,076	0.11%	ADD 7%
67	Vanguard Global Advisers, LLC	50,16350,163	$982,693	0.11%	NEW
68	SteelPeak Wealth, LLC	48,46248,462	$949,371	0.11%	TRIM -13%
69	Trexquant Investment LP	47,86747,867	$937,715	0.11%	TRIM -58%
70	PRICE T ROWE ASSOCIATES INC /MD/	44,90344,903	$880,000	0.10%	ADD 22%
71	Polaris Capital Management, LLC	43,23243,232	$846,915	0.10%	ADD 22%
72	WELLS FARGO & COMPANY/MN	42,01942,019	$823,149	0.10%	TRIM -7%
73	HSBC HOLDINGS PLC	38,01738,017	$753,497	0.09%	NEW
74	Man Group plc	37,27437,274	$730,198	0.08%	ADD 163%
75	CITIGROUP INC	35,90435,904	$703,359	0.08%	ADD 27%
76	Legato Capital Management LLC	34,13534,135	$668,705	0.08%	ADD 28%
77	SEGALL BRYANT & HAMILL, LLC	33,31833,318	$652,700	0.08%	ADD 198%
78	DEUTSCHE BANK AG\	33,13133,131	$649,036	0.08%	ADD 12%
79	SG Americas Securities, LLC	32,80632,806	$643,000	0.07%	TRIM -65%
80	SummerHaven Investment Management, LLC	32,63332,633	$639,280	0.07%	TRIM -15%
81	Quadrature Capital Ltd	30,56130,561	$598,690	0.07%	NEW
82	CANADA LIFE ASSURANCE Co	30,21630,216	$593,000	0.07%	—
83	Freestone Grove Partners LP	29,85729,857	$584,899	0.07%	ADD 8%
84	Squarepoint Ops LLC	28,34528,345	$555,279	0.06%	ADD 91%
85	CALIFORNIA STATE TEACHERS RETIREMENT SYSTEM	28,29928,299	$554,377	0.06%	TRIM -21%
86	Illumine Investment Management, LLC	28,07828,078	$550,048	0.06%	—
87	State of Alaska, Department of Revenue	27,41027,410	$536,000	0.06%	—
88	Advisor OS, LLC	25,40525,405	$497,684	0.06%	—
89	ADVISORY RESEARCH INC	25,33525,335	$496,313	0.06%	ADD 67%
90	INTECH INVESTMENT MANAGEMENT LLC	24,20724,207	$474,215	0.05%	TRIM -62%
91	Thrivent Financial for Lutherans	23,61823,618	$463,000	0.05%	TRIM -3%
92	Vident Advisory, LLC	23,24423,244	$455,350	0.05%	ADD 14%
93	VANGUARD ASSET MANAGEMENT, Ltd	23,05223,052	$451,589	0.05%	NEW
94	NEW YORK STATE TEACHERS RETIREMENT SYSTEM	21,82521,825	$428,000	0.05%	TRIM -5%
95	BARCLAYS PLC	21,28321,283	$416,934	0.05%	TRIM -72%
96	MetLife Investment Management, LLC	20,76120,761	$406,708	0.05%	—
97	Round Rock Advisors LLC	20,49520,495	$401,497	0.05%	—
98	Illinois Municipal Retirement Fund	19,52819,528	$382,554	0.04%	TRIM -7%
99	RAYMOND JAMES FINANCIAL INC	19,05519,055	$373,288	0.04%	TRIM -77%
100	Verition Fund Management LLC	18,59718,597	$364,315	0.04%	NEW

† 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

BlackRock, Inc.

6.1M

5.7M

5.5M

5.4M

$106M

DIMENSIONAL FUND ADVISORS LP

1.2M

1.4M

1.6M

1.8M

2.0M

$40M

STATE STREET CORP

1.6M

1.5M

1.6M

$31M

VANGUARD CAPITAL MANAGEMENT LLC

—

1.5M

$30M

TD Asset Management Inc

1.8M

2.2M

2.0M

1.9M

2.0M

1.5M

$30M

FULLER & THALER ASSET MANAGEMENT, INC.

1.1M

1.3M

1.4M

2.8M

1.4M

$27M

MARSHALL WACE, LLP

609K

1.0M

849K

874K

1.2M

1.0M

$20M

AMERICAN CENTURY COMPANIES INC

472K

308K

233K

289K

665K

1.0M

$20M

GEODE CAPITAL MANAGEMENT, LLC

916K

955K

973K

923K

887K

977K

$19M

Boston Trust Walden Corp

979K

1.2M

1.1M

945K

$19M

Epoch Investment Partners, Inc.

1.1M

1.3M

1.2M

1.1M

899K

$18M

VANGUARD PORTFOLIO MANAGEMENT LLC

—

788K

$15M

D. E. Shaw & Co., Inc.

119K

29K

294K

517K

557K

666K

$13M

LSV ASSET MANAGEMENT

36K

43K

73K

110K

652K

$13M

Invesco Ltd.

299K

359K

387K

390K

501K

605K

$12M

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	213	32,081,025	72.8%	$629M
2025-Q4	235	34,988,447	79.4%	$937M
2025-Q3	243	33,018,500

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 · AMPH

Large holders — 13G, passive (top 4 by % of class)

Holder	% of class	Type	As of
Zhang Jack Y.	24.8%	Exempt	2024-12-31	SEC →
BlackRock, Inc.	11.5%	QII	2025-09-30	SEC →
DIMENSIONAL FUND ADVISORS LP	5.2%	QII	2026-06-30	SEC →
VANGUARD GROUP INC	0%	QII	2026-03-13	SEC →

Source: SEC Schedule 13D/13G structured XML. 13D = active intent; 13G filers report passively (Rule 13d-1(b) QII / 13d-1(c) Passive / 13d-1(d) Exempt) and are not activists. Percent and delta are the group aggregate the filing reports. Structured 13D/G coverage begins December 2024 (SEC XML mandate).

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

213 holders

% of shares outstanding held

72.8%

Shares held (13F)

32,081,025

Reporting holders

213

Top holders

largest 100 of 213 · Δ vs 2025-Q4

#	Holder	Shares	Value	% of shares out	Δ QoQ
1	BlackRock, Inc.	5,421,3435.4M	$106M	12.30%	—
2	DIMENSIONAL FUND ADVISORS LP	2,027,9472.0M	$40M	4.60%	ADD 13%
3	STATE STREET CORP	1,607,5151.6M	$31M	3.65%	ADD 5%
4	VANGUARD CAPITAL MANAGEMENT LLC	1,543,6551.5M	$30M	3.50%	NEW†
5	TD Asset Management Inc	1,541,0441.5M	$30M	3.49%	TRIM -21%
6	FULLER & THALER ASSET MANAGEMENT, INC.	1,395,1391.4M	$27M	3.16%	TRIM -50%
7	MARSHALL WACE, LLP	1,025,6401.0M	$20M	2.33%	TRIM -17%
8	AMERICAN CENTURY COMPANIES INC	1,017,5381.0M	$20M	2.31%	ADD 53%
9	GEODE CAPITAL MANAGEMENT, LLC	976,650976,650	$19M	2.21%	ADD 10%
10	Boston Trust Walden Corp	944,789944,789	$19M	2.14%	TRIM -13%
11	Epoch Investment Partners, Inc.	898,895898,895	$18M	2.04%	TRIM -20%
12	VANGUARD PORTFOLIO MANAGEMENT LLC	787,816787,816	$15M	1.79%	NEW
13	D. E. Shaw & Co., Inc.	665,542665,542	$13M	1.51%	ADD 19%
14	LSV ASSET MANAGEMENT	651,714651,714	$13M	1.48%	ADD 491%
15	Invesco Ltd.	604,774604,774	$12M	1.37%	ADD 21%
16	RENAISSANCE TECHNOLOGIES LLC	553,900553,900	$11M	1.26%	—
17	SYSTEMATIC FINANCIAL MANAGEMENT LP	452,898452,898	$9M	1.03%	ADD 4%
18	MORGAN STANLEY	420,337420,337	$8M	0.95%	TRIM -29%
19	UBS Group AG	420,263420,263	$8M	0.95%	ADD 64%
20	ROYCE & ASSOCIATES LP	406,175406,175	$8M	0.92%	ADD 15%
21	NORTHERN TRUST CORP	372,279372,279	$7M	0.84%	—
22	MILLENNIUM MANAGEMENT LLC	371,373371,373	$7M	0.84%	ADD 28%
23	Bridge City Capital, LLC	335,105335,105	$7M	0.76%	ADD 42%
24	BRIDGEWAY CAPITAL MANAGEMENT, LLC	330,457330,457	$6M	0.75%	ADD 2%
25	GOLDMAN SACHS GROUP INC	329,388329,388	$6M	0.75%	TRIM -41%
26	ARROWSTREET CAPITAL, LIMITED PARTNERSHIP	325,291325,291	$6M	0.74%	TRIM -42%
27	CHARLES SCHWAB INVESTMENT MANAGEMENT INC	321,039321,039	$6M	0.73%	TRIM -8%
28	DENALI ADVISORS LLC	266,465266,465	$5M	0.60%	ADD 26%
29	VICTORY CAPITAL MANAGEMENT INC	249,617249,617	$5M	0.57%	TRIM -18%
30	Bank of New York Mellon Corp	243,226243,226	$5M	0.55%	TRIM -6%
31	VANGUARD FIDUCIARY TRUST CO	231,044231,044	$5M	0.52%	NEW
32	PRINCIPAL FINANCIAL GROUP INC	209,131209,131	$4M	0.47%	TRIM -4%
33	RICE HALL JAMES & ASSOCIATES, LLC	187,348187,348	$4M	0.42%	ADD 55%
34	Empowered Funds, LLC	181,332181,332	$4M	0.41%	ADD 9%
35	BANK OF AMERICA CORP /DE/	174,323174,323	$3M	0.40%	ADD 36%
36	VOLORIDGE INVESTMENT MANAGEMENT, LLC	171,188171,188	$3M	0.39%	TRIM -26%
37	BNP PARIBAS FINANCIAL MARKETS	156,077156,077	$3M	0.35%	ADD 29%
38	FIRST TRUST ADVISORS LP	150,591150,591	$3M	0.34%	ADD 7%
39	NEW YORK STATE COMMON RETIREMENT FUND	148,722148,722	$3M	0.34%	ADD 18%
40	Universal- Beteiligungs- und Servicegesellschaft mbH	139,402139,402	$3M	0.32%	ADD 379%
41	FRANKLIN RESOURCES INC	139,305139,305	$3M	0.32%	ADD 435%
42	TWO SIGMA INVESTMENTS, LP	138,148138,148	$3M	0.31%	ADD 40%
43	LAM GROUP, INC.	130,800130,800	$3M	0.30%	—
44	Public Sector Pension Investment Board	126,574126,574	$2M	0.29%	ADD 3%
45	NORDEA INVESTMENT MANAGEMENT AB	123,824123,824	$2M	0.28%	TRIM -4%
46	BESSEMER GROUP INC	122,046122,046	$2M	0.28%	—
47	O'SHAUGHNESSY ASSET MANAGEMENT, LLC	103,929103,929	$2M	0.24%	ADD 19%
48	JPMORGAN CHASE & CO	104,574104,574	$2M	0.24%	TRIM -34%
49	JANE STREET GROUP, LLC	92,47592,475	$2M	0.21%	TRIM -57%
50	XTX Topco Ltd	87,73687,736	$2M	0.20%	ADD 81%
51	RHUMBLINE ADVISERS	83,72183,721	$2M	0.19%	—
52	EXCHANGE TRADED CONCEPTS, LLC	82,41682,416	$2M	0.19%	ADD 775%
53	Legal & General Group Plc	80,91680,916	$2M	0.18%	TRIM -11%
54	AQR CAPITAL MANAGEMENT LLC	78,77878,778	$2M	0.18%	ADD 16%
55	AMERIPRISE FINANCIAL INC	78,77578,775	$2M	0.18%	TRIM -41%
56	ALLIANCEBERNSTEIN L.P.	56,43056,430	$2M	0.13%	TRIM -7%
57	Nuveen, LLC	76,59576,595	$2M	0.17%	—
58	Swiss National Bank	72,60072,600	$1M	0.16%	—
59	Robeco Institutional Asset Management B.V.	66,40766,407	$1M	0.15%	NEW
60	CITADEL ADVISORS LLC	65,54065,540	$1M	0.15%	TRIM -71%
61	HUSSMAN STRATEGIC ADVISORS, INC.	63,00063,000	$1M	0.14%	NEW
62	ALGERT GLOBAL LLC	62,36062,360	$1M	0.14%	TRIM -50%
63	HRT FINANCIAL LP	56,18156,181	$1M	0.13%	NEW
64	UBS AM, a distinct business unit of UBS ASSET MANAGEMENT AMERICAS LLC	55,37555,375	$1M	0.13%	—
65	ASSETMARK, INC	53,73853,738	$1M	0.12%	—
66	PRUDENTIAL FINANCIAL INC	50,69350,693	$993,076	0.11%	ADD 7%
67	Vanguard Global Advisers, LLC	50,16350,163	$982,693	0.11%	NEW
68	SteelPeak Wealth, LLC	48,46248,462	$949,371	0.11%	TRIM -13%
69	Trexquant Investment LP	47,86747,867	$937,715	0.11%	TRIM -58%
70	PRICE T ROWE ASSOCIATES INC /MD/	44,90344,903	$880,000	0.10%	ADD 22%
71	Polaris Capital Management, LLC	43,23243,232	$846,915	0.10%	ADD 22%
72	WELLS FARGO & COMPANY/MN	42,01942,019	$823,149	0.10%	TRIM -7%
73	HSBC HOLDINGS PLC	38,01738,017	$753,497	0.09%	NEW
74	Man Group plc	37,27437,274	$730,198	0.08%	ADD 163%
75	CITIGROUP INC	35,90435,904	$703,359	0.08%	ADD 27%
76	Legato Capital Management LLC	34,13534,135	$668,705	0.08%	ADD 28%
77	SEGALL BRYANT & HAMILL, LLC	33,31833,318	$652,700	0.08%	ADD 198%
78	DEUTSCHE BANK AG\	33,13133,131	$649,036	0.08%	ADD 12%
79	SG Americas Securities, LLC	32,80632,806	$643,000	0.07%	TRIM -65%
80	SummerHaven Investment Management, LLC	32,63332,633	$639,280	0.07%	TRIM -15%
81	Quadrature Capital Ltd	30,56130,561	$598,690	0.07%	NEW
82	CANADA LIFE ASSURANCE Co	30,21630,216	$593,000	0.07%	—
83	Freestone Grove Partners LP	29,85729,857	$584,899	0.07%	ADD 8%
84	Squarepoint Ops LLC	28,34528,345	$555,279	0.06%	ADD 91%
85	CALIFORNIA STATE TEACHERS RETIREMENT SYSTEM	28,29928,299	$554,377	0.06%	TRIM -21%
86	Illumine Investment Management, LLC	28,07828,078	$550,048	0.06%	—
87	State of Alaska, Department of Revenue	27,41027,410	$536,000	0.06%	—
88	Advisor OS, LLC	25,40525,405	$497,684	0.06%	—
89	ADVISORY RESEARCH INC	25,33525,335	$496,313	0.06%	ADD 67%
90	INTECH INVESTMENT MANAGEMENT LLC	24,20724,207	$474,215	0.05%	TRIM -62%
91	Thrivent Financial for Lutherans	23,61823,618	$463,000	0.05%	TRIM -3%
92	Vident Advisory, LLC	23,24423,244	$455,350	0.05%	ADD 14%
93	VANGUARD ASSET MANAGEMENT, Ltd	23,05223,052	$451,589	0.05%	NEW
94	NEW YORK STATE TEACHERS RETIREMENT SYSTEM	21,82521,825	$428,000	0.05%	TRIM -5%
95	BARCLAYS PLC	21,28321,283	$416,934	0.05%	TRIM -72%
96	MetLife Investment Management, LLC	20,76120,761	$406,708	0.05%	—
97	Round Rock Advisors LLC	20,49520,495	$401,497	0.05%	—
98	Illinois Municipal Retirement Fund	19,52819,528	$382,554	0.04%	TRIM -7%
99	RAYMOND JAMES FINANCIAL INC	19,05519,055	$373,288	0.04%	TRIM -77%
100	Verition Fund Management LLC	18,59718,597	$364,315	0.04%	NEW

† 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

BlackRock, Inc.

6.1M

5.7M

5.5M

5.4M

$106M

DIMENSIONAL FUND ADVISORS LP

1.2M

1.4M

1.6M

1.8M

2.0M

$40M

STATE STREET CORP

1.6M

1.5M

1.6M

$31M

VANGUARD CAPITAL MANAGEMENT LLC

—

1.5M

$30M

TD Asset Management Inc

1.8M

2.2M

2.0M

1.9M

2.0M

1.5M

$30M

FULLER & THALER ASSET MANAGEMENT, INC.

1.1M

1.3M

1.4M

2.8M

1.4M

$27M

MARSHALL WACE, LLP

609K

1.0M

849K

874K

1.2M

1.0M

$20M

AMERICAN CENTURY COMPANIES INC

472K

308K

233K

289K

665K

1.0M

$20M

GEODE CAPITAL MANAGEMENT, LLC

916K

955K

973K

923K

887K

977K

$19M

Boston Trust Walden Corp

979K

1.2M

1.1M

945K

$19M

Epoch Investment Partners, Inc.

1.1M

1.3M

1.2M

1.1M

899K

$18M

VANGUARD PORTFOLIO MANAGEMENT LLC

—

788K

$15M

D. E. Shaw & Co., Inc.

119K

29K

294K

517K

557K

666K

$13M

LSV ASSET MANAGEMENT

36K

43K

73K

110K

652K

$13M

Invesco Ltd.

299K

359K

387K

390K

501K

605K

$12M

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	213	32,081,025	72.8%	$629M
2025-Q4	235	34,988,447	79.4%	$937M
2025-Q3	243	33,018,500

Short interest has its own tab now — open SI →

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

Large holders — 13G, passive (top 4 by % of class)

Holder	% of class	Type	As of
Zhang Jack Y.	24.8%	Exempt	2024-12-31	SEC →
BlackRock, Inc.	11.5%	QII	2025-09-30	SEC →
DIMENSIONAL FUND ADVISORS LP	5.2%	QII	2026-06-30	SEC →
VANGUARD GROUP INC	0%	QII	2026-03-13	SEC →

AMPH US Equity☆

Institutional ownership· 13F filers holding AMPH · 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 · AMPH

Institutional ownership· 13F filers holding AMPH · 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 · AMPH

AMPH US Equity