As of September 29, 2026, Amphastar Pharmaceuticals's top three insider holders are Jack Y. Zhang (Ceo Chief Scientific Officer, 4.24Mn shares), Mary Z. Luo (Coo,Chief Scientist Chairman, 1.10Mn shares), Rong Zhou (Senior Evp, Production Center, 174.99K shares).
| # | Insider | Position | Direct | Indirect | Total | Share of Insiders | Last Filed |
|---|---|---|---|---|---|---|---|
| 1 | Jack Y. Zhang | Ceo Chief Scientific Officer | 2,990,052 | 1,245,125 | 4,235,177 | 66.7% | 17 Mar, 2026 |
| 2 | Mary Z. Luo | Coo,Chief Scientist Chairman | 1,104,416 | 0 | 1,104,416 | 17.4% | 11 Jan, 2024 |
| 3 | Rong Zhou | Senior Evp, Production Center | 344,197 | 0 | 344,197 | 5.4% | 17 Sep, 2026 |
| 4 | William J Peters | Cfo, Evp Treasurer | 168,707 | 0 | 168,707 | 2.7% | 23 Sep, 2026 |
| 5 | Howard Lee | Director | 159,350 | 0 | 159,350 | 2.5% | 03 Jun, 2026 |
| 6 | Yakob Liawatidewi | Evp Corp Admin Center | 121,892 | 0 | 121,892 | 1.9% | 17 Mar, 2026 |
| 7 | Floyd F. Petersen | Director | 71,368 | 0 | 71,368 | 1.1% | 15 Dec, 2025 |
| 8 | Michael A Zasloff | Director | 37,667 | 0 | 37,667 | 0.6% | 03 Jun, 2026 |
| 9 | Diane G. Gerst | Evp, Qa Regulatory Affairs | 31,899 | 0 | 31,899 | 0.5% | 03 Jun, 2026 |
| 10 | Richard K Prins | Director | 29,625 | 0 | 29,625 | 0.5% | 12 Aug, 2026 |
| 11 | Gayle Deflin | Director | 19,057 | 0 | 19,057 | 0.3% | 03 Jun, 2026 |
| 12 | David Russell Gaugh | Director | 14,447 | 0 | 14,447 | 0.2% | 03 Jun, 2026 |
| 13 | Anthony T Pierce | Director | 7,886 | 0 | 7,886 | 0.1% | 13 Jul, 2026 |
Each row is that insider’s most recently reported position, from Form 4 filings over the last 60 months — which is why this total does not tie to the quarterly series above, where a quarter counts only the insiders who filed in it. Shares held through a fund or institutional portfolio are counted on the institutional ownership page instead.
| Date | Insider | Position | Transaction | Shares | Price | Value | Shares Held After | Ownership |
|---|---|---|---|---|---|---|---|---|
| 21 Sep, 2026 | William J Peters | Cfo, Evp Treasurer | Disposed S | 4,139 | $25.00 | $103.48K | 168,707 | Direct |
| 16 Sep, 2026 | Rong Zhou | Senior Evp, Production Center | Acquired M | 10,000 | $13.35 | $133.50K | 179,203 | Direct |
| 16 Sep, 2026 | Rong Zhou | Senior Evp, Production Center | Disposed S | 10,000 | $23.94 | $239.40K | 169,203 | Direct |
| 16 Sep, 2026 | Rong Zhou | Senior Evp, Production Center | Disposed M | 10,000 | $0.00 | $0 | 19,424 | Direct |
| 02 Sep, 2026 | Rong Zhou | Senior Evp, Production Center | Disposed S | 3,187 | $23.63 | $75.31K | 169,203 | Direct |
| 11 Aug, 2026 | Richard K Prins | Director | Disposed S | 7,973 | $20.30 | $161.85K | 29,625 | Direct |
| 07 Aug, 2026 | William J Peters | Cfo, Evp Treasurer | Acquired M | 5,053 | $19.79 | $100.00K | 181,026 | Direct |
| 07 Aug, 2026 | William J Peters | Cfo, Evp Treasurer | Disposed S | 8,180 | $22.48 | $183.89K | 172,846 | Direct |
| 07 Aug, 2026 | William J Peters | Cfo, Evp Treasurer | Disposed M | 5,053 | $0.00 | $0 | 0 | Direct |
| 09 Jul, 2026 | Anthony T Pierce | Director | Acquired A | 7,886 | $0.00 | $0 | 7,886 | Direct |
| 09 Jul, 2026 | Anthony T Pierce | Director | Acquired A | 16,646 | $0.00 | $0 | 16,646 | Direct |
| 01 Jun, 2026 | Diane G. Gerst | Director | Acquired A | 8,143 | $0.00 | $0 | 31,899 | Direct |
| 01 Jun, 2026 | Michael A Zasloff | Director | Acquired A | 8,143 | $0.00 | $0 | 37,667 | Direct |
| 01 Jun, 2026 | Howard Lee | Director | Acquired A | 8,143 | $0.00 | $0 | 160,119 | Direct |
| 01 Jun, 2026 | Gayle Deflin | Director | Acquired A | 8,143 | $0.00 | $0 | 19,057 | Direct |
| 01 Jun, 2026 | David Russell Gaugh | Director | Acquired A | 8,143 | $0.00 | $0 | 14,447 | Direct |
| 01 Jun, 2026 | Gayle Deflin | Director | Acquired A | 17,365 | $0.00 | $0 | 17,365 | Direct |
| 01 Jun, 2026 | Diane G. Gerst | Director | Acquired A | 17,365 | $0.00 | $0 | 17,365 | Direct |
| 02 Jun, 2026 | Howard Lee | Director | Disposed F | 769 | $18.45 | $14.19K | 159,350 | Direct |
| 01 Jun, 2026 | David Russell Gaugh | Director | Acquired A | 17,365 | $0.00 | $0 | 17,365 | Direct |