Over the 90-day window ending January 02, 2026, Amphastar Pharmaceuticals's three dominant insider ownership positions are held by Ceo & Chief Scientific Officer Jack Y. Zhang (4.03Mn shares), Senior Evp And Production Center Rong Zhou (138.04K shares), Director Floyd F. Petersen (71.37K shares).
| Holder | Position | Shares | Report Date |
|---|---|---|---|
| Jack Y. Zhang | Ceo & Chief Scientific Officer | 4,033,134 | 16 Jun, 2025 |
| Mary Z. Luo | Coo Andchief Scientist & Chairman | 1,104,416 | 11 Jan, 2024 |
| Richard Koo | 259,289 | 08 Jun, 2021 | |
| Howard Lee | 151,976 | 04 Jun, 2025 | |
| Rong Zhou | Senior Evp And Production Center | 138,043 | 18 Dec, 2025 |
| William J Peters | Cfo And Evp & Treasurer | 124,985 | 20 May, 2025 |
| Yakob Liawatidewi | Evp Corp Admin Center | 90,909 | 18 Mar, 2025 |
| Floyd F. Petersen | 71,368 | 15 Dec, 2025 | |
| Richard K Prins | 35,183 | 25 Nov, 2025 | |
| Michael A Zasloff | 29,524 | 04 Jun, 2025 | |
| Diane G. Gerst | 23,756 | 04 Jun, 2025 | |
| David Maris | 19,170 | 08 Jun, 2021 | |
| Gayle Deflin | 10,914 | 04 Jun, 2025 | |
| David Russell Gaugh | 6,304 | 22 Jul, 2025 |
* Please note that the shares above only reflect shares from the fund portfolio and the institutional portfolio. Shares from the personal portfolio are excluded from this Institutional Ownership Page. See these insiders' latest transactions here on Insider Page.
| Transaction Date | Insider Name | Security Class | Transaction Type | Shares Traded | Price | Shares Remaining | Ownership | Code |
|---|---|---|---|---|---|---|---|---|
| 17 Dec, 2025 | Rong Zhou | Common Stock | A | 9,787 | $11.33 | 147,830 | D | M |
| 17 Dec, 2025 | Rong Zhou | Common Stock | D | 9,787 | $26.20 | 138,043 | D | S |
| 11 Dec, 2025 | Floyd F. Petersen | Common Stock | D | 1,737 | $25.69 | 73,794 | D | S |
| 12 Dec, 2025 | Floyd F. Petersen | Common Stock | D | 2,426 | $25.92 | 71,368 | D | S |
| 25 Nov, 2025 | Richard K Prins | Common Stock | A | 4,179 | $16.69 | 39,362 | D | M |
| 25 Nov, 2025 | Richard K Prins | Common Stock | D | 4,179 | $27.10 | 35,183 | D | S |
| 13 Nov, 2025 | Floyd F. Petersen | Common Stock | A | 16,679 | $16.69 | 92,210 | D | M |
| 13 Nov, 2025 | Floyd F. Petersen | Common Stock | D | 16,679 | $26.49 | 75,531 | D | S |
| 03 Nov, 2025 | Floyd F. Petersen | Common Stock | D | 500 | $25.27 | 75,531 | D | S |
| 01 Oct, 2025 | Floyd F. Petersen | Common Stock | D | 500 | $27.20 | 76,031 | D | S |
| 02 Sep, 2025 | Floyd F. Petersen | Common Stock | D | 500 | $30.98 | 76,531 | D | S |
| 01 Aug, 2025 | Floyd F. Petersen | Common Stock | D | 500 | $20.83 | 77,031 | D | S |
| 18 Jul, 2025 | David Russell Gaugh | Common Stock | A | 6,304 | $0.00 | 6,304 | D | A |
| 18 Jul, 2025 | David Russell Gaugh | - | - | 6,304 | D | |||
| 02 Jul, 2025 | Floyd F. Petersen | Common Stock | D | 500 | $23.47 | 77,531 | D | S |
| 13 Jun, 2025 | Jack Y. Zhang | Common Stock | A | 200,000 | $13.03 | 2,847,659 | D | M |
| 13 Jun, 2025 | Jack Y. Zhang | - | - | 2,847,659 | D | |||
| 02 Jun, 2025 | Howard Lee | - | - | 152,899 | D | |||
| 02 Jun, 2025 | Floyd F. Petersen | Common Stock | D | 500 | $25.67 | 72,909 | D | S |
| 02 Jun, 2025 | Howard Lee | Common Stock | A | 5,122 | $0.00 | 152,899 | D | A |