AMPH
Amphastar Pharmaceuticals, Inc.
Pharmaceutical PreparationsNasdaqLarge accelerated filer
Total Trades
153
Buys
0
Sells
100
Largest Trade
N/A
Insiders
10
Institutional Funds
193
Inst. Value
$1M+
Activist Filings
15
Insider Trades
| Insider | Title | Type | Value | Shares | Price | Date |
|---|---|---|---|---|---|---|
| Liawatidewi Yakob | EVP Corp Admin Cen… | SELL | $100K–$500K | 11K | $36.64 | Jul 18, 2022 |
| Liawatidewi Yakob | EVP Corp Admin Cen… | EXERCISE | $100K–$500K | 11K | $19.79 | Jul 18, 2022 |
| Gerst Diane G. | Director | SELL | $50K–$100K | 2K | $36.26 | Jul 12, 2022 |
| Gerst Diane G. | Director | EXERCISE | $15K–$50K | 2K | $20.08 | Jul 12, 2022 |
| Gerst Diane G. | Director | EXERCISE | $15K–$50K | 2K | $20.08 | Jul 7, 2022 |
| Gerst Diane G. | Director | SELL | $50K–$100K | 2K | $35.00 | Jul 7, 2022 |
| Petersen Floyd F. | Director | SELL | $15K–$50K | 500 | $34.78 | Jul 5, 2022 |
| Gerst Diane G. | Director | EXERCISE | $100K–$500K | 5K | $20.05 | Jul 5, 2022 |
| Gerst Diane G. | Director | SELL | $100K–$500K | 5K | $35.00 | Jul 5, 2022 |
| PETERS WILLIAM J | CFO, EVP & Treasurer | SELL | $500K+ | 18K | $34.95 | Jul 1, 2022 |
| PETERS WILLIAM J | CFO, EVP & Treasurer | EXERCISE | $100K–$500K | 18K | $14.95 | Jul 1, 2022 |
| PETERS WILLIAM J | CFO, EVP & Treasurer | SELL | $100K–$500K | 6K | $32.05 | Jun 22, 2022 |
| Lee Howard | Director | EXERCISE | $100K–$500K | 10K | $17.11 | Jun 7, 2022 |
| Lee Howard | Director | SELL | $100K–$500K | 10K | $37.79 | Jun 7, 2022 |
| Petersen Floyd F. | Director | SELL | $15K–$50K | 500 | $37.00 | Jun 2, 2022 |
| Lee Howard | Director | SELL | $100K–$500K | 10K | $34.93 | May 26, 2022 |
| Lee Howard | Director | EXERCISE | $100K–$500K | 10K | $17.11 | May 26, 2022 |
| Zhang Jack Y. | CEO & Chief Scient… | SELL | $100K–$500K | 11K | $34.21 | May 23, 2022 |
| Zhang Jack Y. | CEO & Chief Scient… | SELL | $1M+ | 109K | $34.00 | May 20, 2022 |
| Petersen Floyd F. | Director | EXERCISE | $100K–$500K | 20K | $17.11 | May 19, 2022 |
| Petersen Floyd F. | Director | SELL | $100K–$500K | 10K | $35.05 | May 19, 2022 |
| Zhang Jack Y. | CEO & Chief Scient… | SELL | $1M+ | 118K | $35.75 | May 18, 2022 |
| ZASLOFF MICHAEL A | Director | EXERCISE | $100K–$500K | 10K | $17.11 | May 17, 2022 |
| ZASLOFF MICHAEL A | Director | SELL | $100K–$500K | 10K | $35.61 | May 17, 2022 |
| Petersen Floyd F. | Director | SELL | $1K–$15K | 295 | $35.18 | May 4, 2022 |
| Petersen Floyd F. | Director | SELL | $15K–$50K | 500 | $36.69 | Apr 5, 2022 |
| PETERS WILLIAM J | CFO, EVP & Treasurer | SELL | $1M+ | 51K | $33.96 | Mar 18, 2022 |
| PETERS WILLIAM J | CFO, EVP & Treasurer | EXERCISE | $500K+ | 51K | $14.40 | Mar 18, 2022 |
| PRINS RICHARD K | Director | EXERCISE | $100K–$500K | 10K | $17.11 | Mar 18, 2022 |
| PRINS RICHARD K | Director | SELL | $100K–$500K | 10K | $34.02 | Mar 18, 2022 |
| PETERS WILLIAM J | CFO, EVP & Treasurer | GRANT | N/A | 22K | — | Mar 17, 2022 |
| PETERS WILLIAM J | CFO, EVP & Treasurer | SELL | $100K–$500K | 8K | $34.46 | Mar 17, 2022 |
| ZASLOFF MICHAEL A | Director | EXERCISE | $100K–$500K | 10K | $17.11 | Mar 17, 2022 |
| ZASLOFF MICHAEL A | Director | SELL | $100K–$500K | 10K | $33.71 | Mar 17, 2022 |
| PETERS WILLIAM J | CFO, EVP & Treasurer | EXERCISE | $100K–$500K | 13K | $13.35 | Mar 9, 2022 |
| PETERS WILLIAM J | CFO, EVP & Treasurer | SELL | $100K–$500K | 13K | $29.35 | Mar 9, 2022 |
| Petersen Floyd F. | Director | SELL | $1K–$15K | 500 | $27.27 | Mar 1, 2022 |
| Zhou Rong | EVP | SELL | $100K–$500K | 13K | $28.77 | Mar 1, 2022 |
| Zhou Rong | EVP | EXERCISE | $50K–$100K | 7K | $10.93 | Mar 1, 2022 |
| PETERS WILLIAM J | CFO, EVP & Treasurer | SELL | $500K+ | 23K | $28.47 | Mar 1, 2022 |
| PETERS WILLIAM J | CFO, EVP & Treasurer | EXERCISE | $100K–$500K | 23K | $14.95 | Mar 1, 2022 |
| Zhou Rong | EVP | EXERCISE | $50K–$100K | 7K | $10.93 | Feb 10, 2022 |
| Zhou Rong | EVP | SELL | $100K–$500K | 7K | $26.77 | Feb 10, 2022 |
| PETERS WILLIAM J | CFO, EVP & Treasurer | SELL | $100K–$500K | 10K | $26.95 | Feb 10, 2022 |
| PETERS WILLIAM J | CFO, EVP & Treasurer | EXERCISE | $100K–$500K | 10K | $14.95 | Feb 10, 2022 |
| Petersen Floyd F. | Director | SELL | $1K–$15K | 500 | $24.08 | Feb 2, 2022 |
| Zhou Rong | EVP | SELL | $500K+ | 21K | $25.36 | Jan 12, 2022 |
| Zhou Rong | EVP | EXERCISE | $100K–$500K | 14K | $10.93 | Jan 12, 2022 |
| PETERS WILLIAM J | CFO, EVP & Treasurer | SELL | $1M+ | 48K | $24.75 | Jan 11, 2022 |
| PETERS WILLIAM J | CFO, EVP & Treasurer | EXERCISE | $500K+ | 48K | $14.40 | Jan 11, 2022 |
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Institutional Ownership
13F filings as of Dec 31, 2025 · 193 funds holding
| Fund | Shares | Value | Type |
|---|---|---|---|
| TD ASSET MANAGEMENT INC | 2.0M | $1M+ | SH |
| DIMENSIONAL FUND ADVISORS LP | 1.7M | $1M+ | SH |
| STATE STREET CORP | 1.5M | $1M+ | SH |
| FULLER & THALER ASSET MANAGEMENT, INC. | 1.4M | $1M+ | SH |
| FULLER & THALER ASSET MANAGEMENT, INC. | 1.4M | $1M+ | SH |
| Epoch Investment Partners, Inc. | 1.1M | $1M+ | SH |
| GEODE CAPITAL MANAGEMENT, LLC | 770K | $1M+ | SH |
| Boston Trust Walden Corp | 668K | $1M+ | SH |
| AMERICAN CENTURY COMPANIES INC | 665K | $1M+ | SH |
| ARROWSTREET CAPITAL, LIMITED PARTNERSHIP | 559K | $1M+ | SH |
| RENAISSANCE TECHNOLOGIES LLC | 545K | $1M+ | SH |
| ROYCE & ASSOCIATES LP | 352K | $1M+ | SH |
| CHARLES SCHWAB INVESTMENT MANAGEMENT INC | 351K | $1M+ | SH |
| VICTORY CAPITAL MANAGEMENT INC | 305K | $1M+ | SH |
| Bridge City Capital, LLC | 235K | $1M+ | SH |
| VOLORIDGE INVESTMENT MANAGEMENT, LLC | 231K | $1M+ | SH |
| MARSHALL WACE, LLP | 215K | $1M+ | SH |
| DENALI ADVISORS LLC | 212K | $1M+ | SH |
| Pacer Advisors, Inc. | 178K | $1M+ | SH |
| Empowered Funds, LLC | 166K | $1M+ | SH |
Activist & 5%+ Owners
SC 13D/13G filings — investors holding 5%+ of outstanding shares
SC 13G/A · Oct 17, 2025
11.5%
5.3M shares
SC 13G/A · Feb 8, 2025
24.8%
12.5M shares
SC 13G/A · Mar 6, 2024
4.5%
2.2M shares
The Vanguard Group - 23-1945930
SC 13G/A · Feb 13, 2024
5.9%
2.8M shares
SC 13G/A · Feb 9, 2024
26.2%
13.4M shares
SC 13G/A · Jan 23, 2024
12.6%
6.0M shares
SC 13G/A · Jan 17, 2024
6.8%
3.3M shares
SC 13G/A · Feb 1, 2023
6.8%
3.3M shares
SC 13G/A · Jan 27, 2023
25.5%
13.1M shares
SC 13G/A · Jan 26, 2023
14.6%
7.0M shares
SC 13G/A · Jan 20, 2023
14.6%
7.0M shares
(entities only Federated Hermes, Inc.
SC 13G/A · Feb 14, 2022
7.2%
3.5M shares
(entities only Federated Hermes, Inc.
SC 13G/A · Feb 14, 2022
7.3%
10.2M shares
SC 13G/A · Feb 11, 2022
25.5%
12.8M shares
SC 13G/A · Jan 28, 2022
15.0%
7.2M shares