Who owns Amphastar Pharmaceuticals, Inc.?
Prices and market caps: Cboe delayed data, at least 15 minutes delayed. Not real-time. Fundamentals from company filings.
Institutional ownership of AMPH from SEC Form 13F filings across 213 reporting managers. All positions are from one synchronized reporting period — 2026-06-30 books, filed up to 45 days after quarter end — so every row is comparable.
As of the 2026-06-30 reporting period, 213 institutions disclosed 29.3M shares of Amphastar Pharmaceuticals, Inc. worth $545.0M — about 67.2% of shares outstanding; the largest disclosed holder is BlackRock, Inc.. Source: SEC Form 13F filings, parsed by EvidInvest.
213
13F holders
$545.0M
value, 2026 filers
67.2%
of shares outstanding (29.3M sh)
37
new positions (2026 filers)
Top institutional holders
ordered by shares owned · positions as of 2026-06-30 · % of fund = share of the manager's own book · % of co. = share of AMPH's shares outstanding
| # | Manager | Shares | Value | % of fund | % of co. | Δ shares QoQ |
|---|---|---|---|---|---|---|
| 1 | BlackRock, Inc. | 5.2M | $105.4M | 0.0% | 12% | -3.6% |
| 2 | DIMENSIONAL FUND ADVISORS LP | 2.3M | $46.5M | 0.0% | 5.3% | +13.7% |
| 3 | STATE STREET CORP | 1.6M | $33.1M | 0.0% | 3.8% | +2.2% |
| 4 | VANGUARD CAPITAL MANAGEMENT LLC | 1.5M | $29.9M | 0.0% | 3.4% | -4.0% |
| 5 | AMERICAN CENTURY COMPANIES INC | 1.2M | $23.7M | 0.0% | 2.7% | +15.6% |
| 6 | MARSHALL WACE, LLP | 1.1M | $21.5M | 0.0% | 2.4% | +4.0% |
| 7 | GEODE CAPITAL MANAGEMENT, LLC | 969,840 | $19.6M | 0.0% | 2.2% | -0.7% |
| 8 | FULLER & THALER ASSET MANAGEMENT, INC. | 949,238 | $19.2M | 0.1% | 2.2% | -32.0% |
| 9 | D. E. Shaw & Co., Inc. | 887,048 | $17.9M | 0.0% | 2% | +33.3% |
| 10 | VANGUARD PORTFOLIO MANAGEMENT LLC | 809,568 | $16.3M | 0.0% | 1.9% | +2.8% |
| 11 | CALIFORNIA STATE TEACHERS RETIREMENT SYSTEM | 729,527 | $36,151 | 0.0% | 1.7% | +2477.9% |
| 12 | LSV ASSET MANAGEMENT | 642,014 | $12,956 | 0.0% | 1.5% | -1.5% |
| 13 | RENAISSANCE TECHNOLOGIES LLC | 525,100 | $10.6M | 0.0% | 1.2% | -5.2% |
| 14 | GOLDMAN SACHS GROUP INC | 505,360 | $10.2M | 0.0% | 1.2% | +53.4% |
| 15 | SYSTEMATIC FINANCIAL MANAGEMENT LP | 437,384 | $8.8M | 0.2% | 1% | -3.4% |
| 16 | MORGAN STANLEY | 434,840 | $8.8M | 0.0% | 1% | +3.5% |
| 17 | UBS Group AG | 393,110 | $7.9M | 0.0% | 0.9% | -6.5% |
| 18 | HRT FINANCIAL LP | 387,530 | $7,820 | 0.0% | 0.9% | +589.8% |
| 19 | DENALI ADVISORS LLC | 375,965 | $7.6M | 0.8% | 0.9% | +41.1% |
| 20 | NORTHERN TRUST CORP | 370,991 | $7.5M | 0.0% | 0.9% | -0.3% |
| 21 | Bridge City Capital, LLC | 338,708 | $6.8M | 1.6% | 0.8% | +1.1% |
| 22 | CHARLES SCHWAB INVESTMENT MANAGEMENT INC | 310,178 | $6.3M | 0.0% | 0.7% | -3.4% |
| 23 | Sixth Street Partners Management Company, L.P.NEW | 310,178 | $6.3M | 1.1% | 0.7% | new |
| 24 | BRIDGEWAY CAPITAL MANAGEMENT, LLC | 298,954 | $6.0M | 0.1% | 0.7% | -9.5% |
| 25 | ROYCE & ASSOCIATES LP | 294,758 | $5.9M | 0.0% | 0.7% | -27.4% |
Source: SEC Form 13F-HR filings (institutional managers over $100M in US-listed positions). 13Fs disclose long positions only, up to 45 days after quarter end; each manager's latest filed quarter is shown per row and dollar values are the manager's filed marks. Aggregates labeled "2026 filers" count only managers whose latest book is a 2026 quarter. Related: valuation · options positioning · supply chain. Research, not investment advice.