Amphastar Pharmaceuticals
Maker of technically demanding generic and branded injectable, inhalation, and intranasal drugs.
$22.01
After-hours close0.00 (0.00%)
At close$22.01(+0.59%)
Something off on this page? Send us feedback.
Breakdown13F · Form 4
Institutions 66.52%29.33M sharesInsiders 11.46%5.05M sharesOther 22.02%9.71M shares
Shares outstanding 44.09M · Float 32.83M · 74.5% free float
Institutions13F, as of Jun 30, 2026
213 holders · 29.33M shares · 34 new positions · 96 increased · 75 reduced · 38 closed
| Holder | Shares | % outstanding | Chg q/q | Filed |
|---|---|---|---|---|
| BlackRock, Inc. | 5.22M | 11.85% | −196.4K | Aug 7, 2026 |
| Dimensional Fund Advisors LP | 2.31M | 5.23% | +277.2K | Aug 11, 2026 |
| State Street Corp | 1.64M | 3.72% | +34.6K | Aug 7, 2026 |
| Vanguard Capital Management LLC | 1.48M | 3.36% | −61.7K | Aug 13, 2026 |
| American Century Companies Inc | 1.18M | 2.67% | +159.1K | Aug 12, 2026 |
| Marshall Wace, LLP | 1.07M | 2.42% | +40.7K | Aug 13, 2026 |
| Geode Capital Management, LLC | 969.8K | 2.20% | −6.8K | Aug 12, 2026 |
| Fuller & Thaler Asset Management, Inc. | 949.2K | 2.15% | −445.9K | Aug 12, 2026 |
Beneficial owners13D/G · 5% or more, as filed
| Holder | % of class | Shares | Form | Filed |
|---|---|---|---|---|
| Jack Y. Zhang | 24.80% | 12.52M | 13G | Feb 7, 2025 ↗ |
| BlackRock, Inc. | 11.50% | 5.33M | 13G | Oct 17, 2025 ↗ |
| Dimensional Fund Advisors LP | 5.20% | 2.31M | 13G | Jul 14, 2026 ↗ |
InsidersForm 4
| Insider | Role | Shares | % outstanding | Filed |
|---|---|---|---|---|
| Jack Y. Zhang | director, 10 percent owner, officer: CEO & CHIEF SCIENTIFIC OFFICER | 4.24M | 9.61% | Mar 17, 2026 |
| William J. Peters | director, officer: CFO, EVP & TREASURER | 172.8K | 0.39% | Aug 11, 2026 |
| Rong Zhou | officer: SENIOR EVP, PRODUCTION CENTER | 171.6K | 0.39% | Mar 17, 2026 |
| Howard Lee | director | 159.4K | 0.36% | Jun 3, 2026 |
| Yakob Liawatidewi | director, officer: EVP CORP ADMIN CENTER | 121.9K | 0.28% | Mar 17, 2026 |
| Floyd F. Petersen | director | 71.4K | 0.16% | Dec 15, 2025 |
| Diane G. Gerst | director | 31.9K | 0.07% | Jun 3, 2026 |
| Richard K. Prins | director | 29.6K | 0.07% | Aug 12, 2026 |
| Gayle Deflin | director | 19.1K | 0.04% | Jun 3, 2026 |
| Michael A. Zasloff | director | 17.4K | 0.04% | Jun 3, 2026 |
4 ten-percent owners hold 7.75M shares by Form 4, outside the officers-and-directors figure above · 5 people have not refiled in the last 18 months (1.59M shares), so they are not in the figure above
Latest trades
| Date | Insider | Type | Shares | Avg price | Owned after |
|---|---|---|---|---|---|
| Aug 11, 2026 | Richard K. Prinsdirector | Sale | 7,973 | $20.30 | 29,625 |
| Aug 7, 2026 | William J. Petersdirector, officer: CFO, EVP & TREASURER | Sale | 8,180 | $22.48 | 172,846 |
| Dec 17, 2025 | Rong Zhouofficer: SENIOR EVP, PRODUCTION CENTER | Sale | 9,787 | $26.20 | 138,043 |
| Dec 12, 2025 | Floyd F. Petersendirector | Sale | 2,426 | $25.92 | 71,368 |
| Dec 11, 2025 | Floyd F. Petersendirector | Sale | 1,737 | $25.69 | 73,794 |
| Nov 25, 2025 | Richard K. Prinsdirector | Sale | 4,179 | $27.10 | 35,183 |
| Nov 13, 2025 | Floyd F. Petersendirector | Sale | 16,679 | $26.49 | 75,531 |
| Nov 3, 2025 | Floyd F. Petersendirector | Sale | 500 | $25.27 | 75,531 |
| Oct 1, 2025 | Floyd F. Petersendirector | Sale | 500 | $27.20 | 76,031 |
| Sep 2, 2025 | Floyd F. Petersendirector | Sale | 500 | $30.98 | 76,531 |
CongressHouse and Senate disclosures
Not reported.