AMPH · Insider Trading
Amphastar Pharmaceuticals, Inc.
Every open-market purchase and sale reported by AMPH officers, directors and 10%+ beneficial owners on SEC Form 4, which must be filed within two business days of the transaction. Sales often reflect scheduled 10b5-1 plans or tax withholding rather than a directional view, so read counts alongside the size and the filer.
| Filed | Insider | Role | Type | Shares | Value |
|---|---|---|---|---|---|
| 2026-09-23 | William J Peters | CFO, EVP & TREASURER | Sell | −4,139 | −$103.47K |
| 2026-09-17 | Rong Zhou | SENIOR EVP, PRODUCTION CENTER | MIXED | — | −$105.90K |
| 2026-09-03 | Rong Zhou | SENIOR EVP, PRODUCTION CENTER | Sell | −3,187 | −$75.31K |
| 2026-08-12 | Richard K Prins | Director | Sell | −7,973 | −$161.85K |
| 2026-08-11 | William J Peters | CFO, EVP & TREASURER | MIXED | −3,127 | −$83.89K |
| 2026-07-13 | Anthony T Pierce | Director | A | +7,886 | — |
| 2026-06-03 | Michael A Zasloff | Director | A | +8,143 | — |
| 2026-06-03 | Richard K Prins | Director | MIXED | +6,643 | — |
| 2026-06-03 | Howard Lee | Director | MIXED | +7,374 | −$14.19K |
| 2026-06-03 | Gayle Deflin | Director | A | +8,143 | — |
| 2026-06-03 | David Russell Gaugh | Director | A | +8,143 | — |
| 2026-06-03 | Diane G. Gerst | Director | A | +8,143 | — |
| 2026-03-17 | Rong Zhou | SENIOR EVP, PRODUCTION CENTER | F | −1,225 | −$22.27K |
| 2026-03-17 | Yakob Liawatidewi | EVP CORP ADMIN CENTER | F | −1,033 | −$18.78K |
| 2026-03-17 | Jack Y. Zhang | CEO & CHIEF SCIENTIFIC OFFICER | F | −25,384 | −$461.48K |
| 2026-03-17 | William J Peters | CFO, EVP & TREASURER | F | −1,973 | −$35.87K |
| 2026-03-11 | Yakob Liawatidewi | EVP CORP ADMIN CENTER | MIXED | +33,580 | −$35.36K |
| 2026-03-11 | William J Peters | CFO, EVP & TREASURER | MIXED | +55,396 | −$62.35K |
| 2026-03-11 | Jack Y. Zhang | CEO & CHIEF SCIENTIFIC OFFICER | MIXED | +467,572 | −$725.39K |
| 2026-03-11 | Rong Zhou | SENIOR EVP, PRODUCTION CENTER | MIXED | +37,217 | −$41.89K |
| 2026-03-10 | William J Peters | CFO, EVP & TREASURER | F | −2,146 | −$41.50K |
| 2026-03-10 | Yakob Liawatidewi | EVP CORP ADMIN CENTER | F | −1,144 | −$22.12K |
| 2026-03-10 | Rong Zhou | SENIOR EVP, PRODUCTION CENTER | F | −1,357 | −$26.24K |
| 2026-03-10 | Jack Y. Zhang | CEO & CHIEF SCIENTIFIC OFFICER | F | −21,700 | −$419.68K |
| 2026-03-06 | William J Peters | CFO, EVP & TREASURER | F | −1,744 | −$34.81K |
| 2026-03-06 | Rong Zhou | SENIOR EVP, PRODUCTION CENTER | F | −1,124 | −$22.44K |
| 2026-03-06 | Yakob Liawatidewi | EVP CORP ADMIN CENTER | F | −965 | −$19.26K |
| 2026-03-06 | Mary Z. Luo | COO, Chief Scientist, Chairman | F | −16,402 | −$327.38K |
| 2025-12-18 | Rong Zhou | SENIOR EVP, PRODUCTION CENTER | MIXED | — | −$145.49K |
| 2025-12-15 | Floyd F. Petersen | Director | Sell | −4,163 | −$107.51K |
| 2025-11-25 | Richard K Prins | Director | MIXED | — | −$43.51K |
| 2025-11-17 | Floyd F. Petersen | Director | MIXED | — | −$163.46K |
| 2025-11-05 | Floyd F. Petersen | Director | Sell | −500 | −$12.63K |
| 2025-10-02 | Floyd F. Petersen | Director | Sell | −500 | −$13.60K |
| 2025-09-03 | Floyd F. Petersen | Director | Sell | −500 | −$15.49K |
| 2025-08-04 | Floyd F. Petersen | Director | Sell | −500 | −$10.42K |
| 2025-07-22 | David Russell Gaugh | Director | A | +6,304 | — |
| 2025-07-03 | Floyd F. Petersen | Director | Sell | −500 | −$11.73K |
| 2025-06-16 | Mary Z. Luo | COO, Chief Scientist, Chairman | M | +400,000 | +$5.21M |
| 2025-06-04 | Diane G. Gerst | Director | A | +5,122 | — |
| 2025-06-04 | Richard K Prins | Director | A | +5,122 | — |
| 2025-06-04 | Howard Lee | Director | MIXED | +4,199 | −$24.01K |
| 2025-06-04 | Gayle Deflin | Director | A | +5,122 | — |
| 2025-06-04 | Floyd F. Petersen | Director | MIXED | +4,622 | −$12.84K |
| 2025-06-04 | Michael A Zasloff | Director | A | +5,122 | — |
| 2025-05-20 | William J Peters | CFO, EVP & TREASURER | F | −273 | −$6.77K |
| 2025-05-02 | Floyd F. Petersen | Director | Sell | −500 | −$12.04K |
| 2025-04-02 | Floyd F. Petersen | Director | Sell | −500 | −$14.19K |
| 2025-03-18 | William J Peters | CFO, EVP & TREASURER | F | −4,972 | −$135.65K |
| 2025-03-18 | Yakob Liawatidewi | EVP CORP ADMIN CENTER | F | −2,762 | −$75.42K |
| Insider | Role | Shares Held | Value |
|---|---|---|---|
| Mary Z. Luo | COO, Chief Scientist, Chairman | 9,669,569 | $251.89M |
| Jack Y. Zhang | CEO & CHIEF SCIENTIFIC OFFICER | 4,235,177 | $110.33M |
| Rong Zhou | SENIOR EVP, PRODUCTION CENTER | 184,203 | $4.80M |
| William J Peters | CFO, EVP & TREASURER | 168,707 | $4.39M |
| Howard Lee | Director | 160,119 | $4.17M |
| Yakob Liawatidewi | EVP CORP ADMIN CENTER | 124,351 | $3.24M |
| Floyd F. Petersen | Director | 73,794 | $1.92M |
| Michael A Zasloff | Director | 37,667 | $981.23K |
| Diane G. Gerst | Director | 31,899 | $830.97K |
| Richard K Prins | Director | 29,625 | $771.73K |
| Gayle Deflin | Director | 19,057 | $496.43K |
| David Russell Gaugh | Director | 14,447 | $376.34K |
| Anthony T Pierce | Director | 7,886 | $205.43K |
Form 4 reports a change in beneficial ownership by an officer, director or 10%+ holder, and must be filed within two business days of the transaction — so this is close to real time, unlike the 45-day-lagged 13F institutional data.
Transaction codes matter more than the raw buy/sell count. Code P is an open-market purchase — an insider choosing to buy with their own money, which is the signal most research treats as informative. Code S is a sale, but sales are frequently pre-scheduled under a 10b5-1 plan or cover tax withholding on vesting equity, so a run of sales often says nothing directional. Codes A and M are grants and option exercises rather than open-market decisions.
Full filing history and per-insider positions are on the AMPH quote page; the site-wide leaderboard is on the insider transactions hub.
Market data may be delayed, incomplete, or inaccurate. Not a recommendation to buy, sell, or hold any security. Verify quotes with your broker before trading. See Terms §17.