AMPHNasdaqPharmaceutical PreparationsFiscal year ends December 31
Amphastar Pharmaceuticals, Inc.
Financials through Q2 FY2026, quarter ended Jun 30, 2026Last filing: 10-Q on Aug 6, 2026
$26.14+0.27 (+1.04%)
Close on Oct 19, 2026
- Market cap
- $1.16B
- P/E (TTM)
- 15.4
- Dividend yield
- –
Ownership
Institutional holdings as of Jun 30, 2026, from 13F filings
Held by institutions
66.6%
28M of 43M shares
Institutional holders
210
33 new, 33 sold out
Net institutional buying
-4M
In Q2 2026
Insider trades, 12 months
0 buys · 11 sales
Net sold $1.70M
Shares held by institutions
Holders of more than 5%
Latest Schedule 13D (active) or 13G (passive) filed by each holder
| Holder | Shares | % of class | Filing | As of |
|---|---|---|---|---|
| BlackRock, Inc. | 5,333,463 | 11.50% | 13G (passive) amendment | Sep 30, 2025 |
| Dimensional Fund Advisors LP | 2,305,107 | 5.20% | 13G (passive) | Jun 30, 2026 |
| Jack Y. Zhang | 12,524,153 | 24.80% | 13G (passive) amendment | Dec 31, 2024 |
Top institutional holders
13F holdings as of Jun 30, 2026
| Holder | Shares | % of AMPH | Value | Change | % of portfolio |
|---|---|---|---|---|---|
| BlackRock, Inc. | 5,224,934 | 12.28% | $105.44M | −196,409 | 0.00% |
| Dimensional Fund Advisors LP | 2,305,107 | 5.42% | $46.52M | +277,160 | 0.01% |
| State Street Corp | 1,642,126 | 3.86% | $33.14M | +34,611 | 0.00% |
| Vanguard Capital Management LLC | 1,481,952 | 3.48% | $29.91M | −61,703 | 0.00% |
| American Century Companies Inc | 1,176,626 | 2.77% | $23.74M | +159,088 | 0.01% |
| Marshall Wace, Llp | 1,066,322 | 2.51% | $21.52M | +40,682 | 0.02% |
| Geode Capital Management, LLC | 969,840 | 2.28% | $19.58M | −6,810 | 0.00% |
| Fuller & Thaler Asset Management, Inc. | 949,238 | 2.23% | $19.16M | −445,901 | 0.05% |
| D. E. Shaw & Co., Inc. | 887,048 | 2.09% | $17.90M | +221,506 | 0.01% |
| Vanguard Portfolio Management LLC | 809,568 | 1.90% | $16.34M | +21,752 | 0.00% |
| Lsv Asset Management | 642,014 | 1.51% | $12.96K | −9,700 | 0.02% |
| Renaissance Technologies LLC | 525,100 | 1.23% | $10.60M | −28,800 | 0.01% |
| Goldman Sachs Group Inc | 505,360 | 1.19% | $10.20M | +175,972 | 0.00% |
| Systematic Financial Management LP | 437,384 | 1.03% | $8.83M | −15,514 | 0.18% |
| Morgan Stanley | 434,840 | 1.02% | $8.78M | +14,503 | 0.00% |
| UBS Group AG | 393,110 | 0.92% | $7.93M | −27,153 | 0.00% |
| Hrt Financial LP | 387,530 | 0.91% | $7.82K | +331,349 | 0.00% |
| Denali Advisors LLC | 375,965 | 0.88% | $7.59M | +109,500 | 0.76% |
| Northern Trust Corp | 370,991 | 0.87% | $7.49M | −1,288 | 0.00% |
| Bridge City Capital, LLC | 338,708 | 0.80% | $6.84M | +3,603 | 1.56% |
Institutional buying and selling by quarter
Positions opened, added to, reduced and closed by 13F filers
| Quarter | Holders | Shares held | % of shares | New / added | Reduced / closed | Shares bought | Shares sold |
|---|---|---|---|---|---|---|---|
| Q2 2026 | 210 | 28M | 66.6% | 33 / 64 | 75 / 33 | 3M | 7M |
| Q1 2026 | 215 | 32M | 76.0% | 29 / 68 | 96 / 45 | 6M | 6M |
| Q4 2025 | 236 | 35M | 82.3% | 26 / 95 | 86 / 32 | 5M | 3M |
| Q3 2025 | 243 | 33M | 77.6% | 34 / 83 | 92 / 34 | 4M | 4M |
| Q2 2025 | 245 | 33M | 77.7% | 45 / 91 | 73 / 40 | 4M | 5M |
| Q1 2025 | 241 | 33M | 78.2% | 33 / 80 | 95 / 50 | 4M | 6M |
| Q4 2024 | 263 | 35M | 82.7% | 36 / 84 | 100 / 50 | 4M | 4M |
| Q3 2024 | 279 | 36M | 83.5% | 43 / 99 | 93 / 32 | 10M | 3M |
| Q2 2024 | 269 | 34M | 81.0% | 38 / 99 | 101 / 38 | 3M | 4M |
| Q1 2024 | 271 | 35M | 81.9% | 47 / 89 | 98 / 53 | 4M | 3M |
| Q4 2023 | 277 | 34M | 79.9% | 48 / 99 | 91 / 24 | 5M | 3M |
| Q3 2023 | 256 | 32M | 75.2% | 41 / 90 | 93 / 28 | 2M | 2M |
Top mutual fund and ETF holders
Latest monthly portfolio reports (Form N-PORT)
| Fund | Shares | % of AMPH | Value | % of fund | As of |
|---|---|---|---|---|---|
| iShares Core S&P Small-Cap ETF | 2,045,920 | 4.81% | $41.29M | 0.04% | Jun 30, 2026 |
| Vanguard Total Stock Market Index Fund | 1,055,676 | 2.48% | $21.30M | 0.00% | Jun 30, 2026 |
| Avantis U.S. Small Cap Value ETF | 945,543 | 2.22% | $17.82M | 0.07% | May 31, 2026 |
| Fullerthaler Behavioral Small Cap Equity | 902,737 | 2.12% | $18.22M | 0.14% | Jun 30, 2026 |
| iShares Russell 2000 ETF | 847,727 | 1.99% | $17.11M | 0.02% | Jun 30, 2026 |
| U.S. Small Cap Value Portfolio | 596,077 | 1.40% | $11.89M | 0.06% | Jul 31, 2026 |
| Vanguard Extended Market Index Fund | 391,083 | 0.92% | $7.89M | 0.01% | Jun 30, 2026 |
| Fidelity Small Cap Index Fund | 353,885 | 0.83% | $7.06M | 0.02% | Jul 31, 2026 |
| State Street(R) SPDR(R) Portfolio S&P 600(TM) Small Cap ETF | 306,646 | 0.72% | $6.19M | 0.04% | Jun 30, 2026 |
| iShares Russell 2000 Value ETF | 303,954 | 0.71% | $6.13M | 0.04% | Jun 30, 2026 |
| Dimensional U.S. Targeted Value ETF | 285,363 | 0.67% | $5.69M | 0.04% | Jul 31, 2026 |
| U.S. Targeted Value Portfolio | 276,227 | 0.65% | $5.51M | 0.03% | Jul 31, 2026 |
| Vanguard Tax-Managed Small-Cap Fund | 269,433 | 0.63% | $5.44M | 0.05% | Jun 30, 2026 |
| State Street(R) SPDR(R) S&P(R) Pharmaceuticals ETF | 265,621 | 0.62% | $5.36M | 1.25% | Jun 30, 2026 |
| Dimensional US Small Cap Value ETF | 256,428 | 0.60% | $5.11M | 0.06% | Jul 31, 2026 |
Officers, directors and major owners
People who filed Forms 3, 4 or 5 in the last two years
| Name | Role | Shares owned | % of shares | Latest filing |
|---|---|---|---|---|
| William J. Peters | CFO, EVP & TREASURER, Director | 168,707 | 0.40% | Sep 23, 2026 |
| Jack Y. Zhang | CEO & CHIEF SCIENTIFIC OFFICER, Director, 10% owner | 4,235,177 | 9.96% | Mar 17, 2026 |
| Mary Z. Luo | COO, Chief Scientist, Chairman, Director, 10% owner | 4,014,083 | 9.44% | Mar 17, 2026 |
| Yakob Liawatidewi | EVP CORP ADMIN CENTER, Director | 124,351 | 0.29% | Mar 17, 2026 |
| Rong Zhou | SENIOR EVP, PRODUCTION CENTER | 278,871 | 0.66% | Sep 17, 2026 |
| Richard K. Prins | Director | 29,625 | 0.07% | Aug 12, 2026 |
| Anthony T. Pierce | Director | 7,886 | 0.02% | Jul 13, 2026 |
| Diane G. Gerst | Director | 31,899 | 0.07% | Jun 3, 2026 |
| David Russell Gaugh | Director | 14,447 | 0.03% | Jun 3, 2026 |
| Howard Lee | Director | 159,350 | 0.37% | Jun 3, 2026 |
| Michael A. Zasloff | Director | 37,667 | 0.09% | Jun 3, 2026 |
| Gayle Deflin | Director | 19,057 | 0.04% | Jun 3, 2026 |
| Floyd F. Petersen | Director | 71,368 | 0.17% | Dec 15, 2025 |
Insider trades
Common stock transactions reported on Form 4, newest first
| Insider | Date | Transaction | Shares | Price | Value | Shares after |
|---|---|---|---|---|---|---|
| William J. Peters CFO, EVP & TREASURER, Director | Sep 21, 2026 | Sale(10b5-1 plan) | −4,139 | $25.00 | $103.48K | 168,707 |
| Rong Zhou SENIOR EVP, PRODUCTION CENTER | Sep 16, 2026 | Option exercise | +10,000 | $13.35 | $133.50K | 179,203 |
| Rong Zhou SENIOR EVP, PRODUCTION CENTER | Sep 16, 2026 | Sale | −10,000 | $23.94 | $239.40K | 169,203 |
| Rong Zhou SENIOR EVP, PRODUCTION CENTER | Sep 2, 2026 | Sale | −3,187 | $23.63 | $75.31K | 169,203 |
| Richard K. Prins Director | Aug 11, 2026 | Sale | −7,973 | $20.30 | $161.85K | 29,625 |
| William J. Peters CFO, EVP & TREASURER, Director | Aug 7, 2026 | Sale(10b5-1 plan) | −8,180 | $22.48 | $183.89K | 172,846 |
| William J. Peters CFO, EVP & TREASURER, Director | Aug 7, 2026 | Option exercise | +5,053 | $19.79 | $100.00K | 181,026 |
| Anthony T. Pierce Director | Jul 9, 2026 | Award | +7,886 | – | – | 7,886 |
| Howard Lee Director | Jun 2, 2026 | Tax withholding | −769 | $18.45 | $14.19K | 159,350 |
| David Russell Gaugh Director | Jun 1, 2026 | Award | +8,143 | – | – | 14,447 |
| Howard Lee Director | Jun 1, 2026 | Award | +8,143 | – | – | 160,119 |
| Michael A. Zasloff Director | Jun 1, 2026 | Award | +8,143 | – | – | 37,667 |
| Diane G. Gerst Director | Jun 1, 2026 | Award | +8,143 | – | – | 31,899 |
| Gayle Deflin Director | Jun 1, 2026 | Award | +8,143 | – | – | 19,057 |
| Richard K. Prins Director | Jun 1, 2026 | Award | +8,143 | – | – | 37,598 |
| Jack Y. Zhang CEO & CHIEF SCIENTIFIC OFFICER, Director, 10% owner | Mar 15, 2026 | Tax withholding | −2,908 | $18.18 | $52.87K | 1,245,125 |
| Jack Y. Zhang CEO & CHIEF SCIENTIFIC OFFICER, Director, 10% owner | Mar 15, 2026 | Tax withholding | −9,784 | $18.18 | $177.87K | 2,990,052 |
| Rong Zhou SENIOR EVP, PRODUCTION CENTER | Mar 15, 2026 | Tax withholding | −1,225 | $18.18 | $22.27K | 171,554 |
| Yakob Liawatidewi EVP CORP ADMIN CENTER, Director | Mar 15, 2026 | Tax withholding | −1,033 | $18.18 | $18.78K | 121,892 |
| William J. Peters CFO, EVP & TREASURER, Director | Mar 15, 2026 | Tax withholding | −1,973 | $18.18 | $35.87K | 175,063 |
| Jack Y. Zhang CEO & CHIEF SCIENTIFIC OFFICER, Director, 10% owner | Mar 10, 2026 | Tax withholding | −14,785 | $18.91 | $279.58K | 2,999,836 |
| Jack Y. Zhang CEO & CHIEF SCIENTIFIC OFFICER, Director, 10% owner | Mar 10, 2026 | Tax withholding | −4,395 | $18.91 | $83.11K | 1,248,033 |
| Yakob Liawatidewi EVP CORP ADMIN CENTER, Director | Mar 10, 2026 | Tax withholding | −1,870 | $18.91 | $35.36K | 122,925 |
| William J. Peters CFO, EVP & TREASURER, Director | Mar 10, 2026 | Tax withholding | −3,297 | $18.91 | $62.35K | 177,036 |
| Rong Zhou SENIOR EVP, PRODUCTION CENTER | Mar 10, 2026 | Tax withholding | −2,215 | $18.91 | $41.89K | 172,779 |
| Jack Y. Zhang CEO & CHIEF SCIENTIFIC OFFICER, Director, 10% owner | Mar 9, 2026 | Award | +72,462 | – | – | 1,252,428 |
| Jack Y. Zhang CEO & CHIEF SCIENTIFIC OFFICER, Director, 10% owner | Mar 9, 2026 | Award | +180,504 | – | – | 3,014,621 |
| Yakob Liawatidewi EVP CORP ADMIN CENTER, Director | Mar 9, 2026 | Award | +35,450 | – | – | 124,795 |
| William J. Peters CFO, EVP & TREASURER, Director | Mar 9, 2026 | Award | +58,693 | – | – | 180,333 |
| Rong Zhou SENIOR EVP, PRODUCTION CENTER | Mar 9, 2026 | Award | +39,432 | – | – | 174,994 |
| Mary Z. Luo COO, Chief Scientist, Chairman, Director, 10% owner | Mar 6, 2026 | Tax withholding | −7,773 | $19.34 | $150.33K | 2,834,117 |
| Mary Z. Luo COO, Chief Scientist, Chairman, Director, 10% owner | Mar 6, 2026 | Tax withholding | −3,077 | $19.34 | $59.51K | 1,179,966 |
| William J. Peters CFO, EVP & TREASURER, Director | Mar 6, 2026 | Tax withholding | −2,146 | $19.34 | $41.50K | 121,640 |
| Yakob Liawatidewi EVP CORP ADMIN CENTER, Director | Mar 6, 2026 | Tax withholding | −1,144 | $19.34 | $22.12K | 89,345 |
| Rong Zhou SENIOR EVP, PRODUCTION CENTER | Mar 6, 2026 | Tax withholding | −1,357 | $19.34 | $26.24K | 135,562 |
| Yakob Liawatidewi EVP CORP ADMIN CENTER, Director | Mar 4, 2026 | Tax withholding | −965 | $19.96 | $19.26K | 90,489 |
| Rong Zhou SENIOR EVP, PRODUCTION CENTER | Mar 4, 2026 | Tax withholding | −1,124 | $19.96 | $22.44K | 136,919 |
| Jack Y. Zhang CEO & CHIEF SCIENTIFIC OFFICER, Director, 10% owner | Mar 4, 2026 | Tax withholding | −2,432 | $19.96 | $48.54K | 1,183,043 |
| Jack Y. Zhang CEO & CHIEF SCIENTIFIC OFFICER, Director, 10% owner | Mar 4, 2026 | Tax withholding | −5,769 | $19.96 | $115.15K | 2,841,890 |
| William J. Peters CFO, EVP & TREASURER, Director | Mar 4, 2026 | Tax withholding | −1,744 | $19.96 | $34.81K | 123,786 |
| Rong Zhou SENIOR EVP, PRODUCTION CENTER | Dec 17, 2025 | Sale | −9,787 | $26.20 | $256.42K | 138,043 |
| Rong Zhou SENIOR EVP, PRODUCTION CENTER | Dec 17, 2025 | Option exercise | +9,787 | $11.33 | $110.89K | 147,830 |
| Floyd F. Petersen Director | Dec 12, 2025 | Sale | −2,426 | $25.92 | $62.88K | 71,368 |
| Floyd F. Petersen Director | Dec 11, 2025 | Sale | −1,737 | $25.69 | $44.62K | 73,794 |
| Richard K. Prins Director | Nov 25, 2025 | Option exercise | +4,179 | $16.69 | $69.75K | 39,362 |
| Richard K. Prins Director | Nov 25, 2025 | Sale | −4,179 | $27.10 | $113.25K | 35,183 |
| Floyd F. Petersen Director | Nov 13, 2025 | Option exercise | +16,679 | $16.69 | $278.37K | 92,210 |
| Floyd F. Petersen Director | Nov 13, 2025 | Sale | −16,679 | $26.49 | $441.83K | 75,531 |
| Floyd F. Petersen Director | Nov 3, 2025 | Sale(10b5-1 plan) | −500 | $25.27 | $12.64K | 75,531 |
| Floyd F. Petersen Director | Oct 1, 2025 | Sale(10b5-1 plan) | −500 | $27.20 | $13.60K | 76,031 |
| Floyd F. Petersen Director | Sep 2, 2025 | Sale(10b5-1 plan) | −500 | $30.98 | $15.49K | 76,531 |
| Floyd F. Petersen Director | Aug 1, 2025 | Sale(10b5-1 plan) | −500 | $20.83 | $10.42K | 77,031 |
| David Russell Gaugh Director | Jul 18, 2025 | Award | +6,304 | – | – | 6,304 |
| Floyd F. Petersen Director | Jul 2, 2025 | Sale(10b5-1 plan) | −500 | $23.47 | $11.74K | 77,531 |
| Jack Y. Zhang CEO & CHIEF SCIENTIFIC OFFICER, Director, 10% owner | Jun 13, 2025 | Option exercise | +200,000 | $13.03 | $2.61M | 2,847,659 |
| Howard Lee Director | Jun 3, 2025 | Tax withholding | −923 | $26.01 | $24.01K | 151,976 |
| Richard K. Prins Director | Jun 2, 2025 | Award | +5,122 | – | – | 35,183 |
| Michael A. Zasloff Director | Jun 2, 2025 | Award | +5,122 | – | – | 29,524 |
| Howard Lee Director | Jun 2, 2025 | Award | +5,122 | – | – | 152,899 |
| Gayle Deflin Director | Jun 2, 2025 | Award | +5,122 | – | – | 10,914 |
Awards, option exercises, tax withholding and gifts are shown alongside open-market buys and sales. Each name links to the filing on SEC EDGAR.
Planned insider sales
Notices of proposed sale filed on Form 144 before shares are sold
| Seller | Filed | Shares | Market value | Planned sale | Acquired through |
|---|---|---|---|---|---|
| William J. Peters Officer | Sep 21, 2026 | 4,139 | $103.48K | Sep 21, 2026 | RSU Vesting |
| Zhou Rong Vice President | Sep 1, 2026 | 13,187 | $290.11K | Sep 1, 2026 | Option Exercise |
| Petersen Floyd Director | Aug 18, 2026 | 47,101 | $989.12K | Aug 18, 2026 | Option Exercise |
| Prins Richard Director | Aug 11, 2026 | 7,973 | $161.93K | Aug 11, 2026 | RSU Vesting |
| William J. Peters Officer | Aug 7, 2026 | 8,180 | $183.89K | Aug 7, 2026 | RSU Vesting |
| Petersen Floyd Director | Dec 11, 2025 | 4,163 | $333.04K | Dec 11, 2025 | RSU Vesting |
| Petersen Floyd Director | Dec 10, 2025 | 1,737 | $43.43K | Dec 10, 2025 | RSU Vesting |
| Zhou Rong Officer | Nov 28, 2025 | 20,000 | $500.00K | Nov 28, 2025 | Stock Option Exercising |
| Prins Richard Director | Nov 25, 2025 | 4,179 | $104.48K | Nov 25, 2025 | Stock Option Exercising |
| Petersen Floyd Director | Nov 13, 2025 | 16,679 | $441.84K | Nov 13, 2025 | Stock Option Exercise |
| Floyd F. Petersen Director | Nov 3, 2025 | 500 | $12.65K | Nov 3, 2025 | RSU |
| Floyd F. Petersen Director | Oct 1, 2025 | 500 | $13.37K | Oct 1, 2025 | RSU |
| Floyd F. Petersen Director | Sep 2, 2025 | 500 | $15.45K | Sep 2, 2025 | RSU |
| Floyd F. Petersen Director | Aug 1, 2025 | 500 | $10.43K | Aug 1, 2025 | RSU |
| Floyd F. Petersen Director | Jul 2, 2025 | 500 | $11.72K | Jul 2, 2025 | RSU |