Nasdaq · CIK 0001297184
AMPH Amphastar Pharmaceuticals, Inc.
Insider trading from SEC Form 4. Last filing 20 d ago. Close $26.62 on Oct 9, 2026, +58% from the 52-week low and -9% from the high.
Amphastar Pharmaceuticals, Inc. (AMPH) has 69 SEC Form 4 filings on file from 11 insiders, the latest filed on Sep 23, 2026. In the last 90 days insiders made 0 open-market buys worth $0 and 3 open-market sells worth $418k, net -$418k.
23 open-market trades have been scored at AMPH. The newest: William J Peters (CFO, EVP & TREASURER) sold $103k of stock on Sep 21, 2026, filed Sep 23, 2026, scored 20 (weak), under a 10b5-1 plan. The largest of the 23 shown: Rong Zhou (SENIOR EVP, PRODUCTION CENTER) sold $673k on Dec 12, 2024, scored 33 (weak). 2 insiders sold within 14 days of each other around Sep 21, 2026.
AMPH closed at $26.62 on Oct 9, 2026, 58% above its 52-week low and 9% below its 52-week high.
13 Form 144 notices of planned sales are on file, the latest filed Sep 2, 2025.
Last 90 days
Price and insider trades, last year
Daily candles, adjusted for splits and dividends. Green arrows are insider buys, red are sells, sized by value. Click a marked bar to open the signal.Charts by TradingView Lightweight Charts™
Signals
Open-market buys and sells at Amphastar Pharmaceuticals, Inc., scored.
| Score | Insider | Value | Holdings | Price context | Filed |
|---|---|---|---|---|---|
| 20Weak | William J Peters CFO, EVP & TREASURER sell | $103k 4,139 shares | -2% | +45% from low-17% from high | |
| 21Weak | Rong Zhou SENIOR EVP, PRODUCTION CENTER sell | $239k 10,000 shares | -6% | +42% from low-19% from high | |
| 23Weak | Rong Zhou SENIOR EVP, PRODUCTION CENTER sell | $75k 3,187 shares | -2% | +41% from low-23% from high | |
| 21Weak | Rong Zhou SENIOR EVP, PRODUCTION CENTER sell | $256k 9,787 shares | -7% | +26% from low-36% from high | |
| 33Weak | Floyd F. Petersen director sell | $108k 4,163 shares | -6% | +26% from low-42% from high | |
| 23Weak | Richard K Prins director sell | $113k 4,179 shares | -11% | +34% from low-40% from high | |
| 30Weak | Floyd F. Petersen director sell | $442k 16,679 shares | -18% | +28% from low-43% from high | |
| 0Weak | Floyd F. Petersen director sell | $13k 500 shares | -1% | +23% from low-53% from high | |
| 0Weak | Floyd F. Petersen director sell | $14k 500 shares | -1% | +31% from low-49% from high | |
| 0Weak | Floyd F. Petersen director sell | $15k 500 shares | -1% | +49% from low-42% from high | |
| 0Weak | Floyd F. Petersen director sell | $10k 500 shares | -1% | +3% from low-60% from high | |
| 0Weak | Floyd F. Petersen director sell | $12k 500 shares | -1% | +3% from low-56% from high | |
| 0Weak | Floyd F. Petersen director sell | $13k 500 shares | -1% | +10% from low-52% from high | |
| 0Weak | Floyd F. Petersen director sell | $12k 500 shares | -1% | +4% from low-55% from high | |
| 0Weak | Floyd F. Petersen director sell | $14k 500 shares | -1% | +8% from low-47% from high | |
| 8Weak | Floyd F. Petersen director sell | $28k 1,000 shares | -1% | +3% from low-47% from high | |
| 5Weak | William J Peters CFO, EVP & TREASURER sell | $117k 4,231 shares | -4% | +0% from low-48% from high | |
| 33Weak | Rong Zhou SENIOR EVP, PRODUCTION CENTER sell | $673k 15,000 shares | -12% | - | |
| 30Weak | Richard K Prins director sell | $438k 10,000 shares | -25% | - | |
| 33Weak | Richard K Prins director sell | $244k 5,000 shares | -14% | - | |
| 30Weak | Rong Zhou SENIOR EVP, PRODUCTION CENTER sell | $337k 6,893 shares | -6% | - | |
| 18Weak | William J Peters CFO, EVP & TREASURER sell | $387k 7,426 shares | -7% | - | |
| 8Weak | Yakob Liawatidewi EVP CORP ADMIN CENTER sell | $271k 5,214 shares | -7% | - |
Planned sales
Form 144 notices filed before a sale of restricted or control stock, newest first. The sale itself usually reaches a Form 4 within days. All planned sales
| Filed | Seller | Shares | Value | Sale date | Past 3 months |
|---|---|---|---|---|---|
| Sep 2, 2025 | Petersen Floyd F. Director | 500 0.00% of outstanding | $15k | Sep 2, 2025 | $35k |
| Aug 1, 2025 | Petersen Floyd F. Director | 500 0.00% of outstanding | $10k | Aug 1, 2025 | $37k |
| Jul 2, 2025 | Petersen Floyd F. Director | 500 0.00% of outstanding | $12k | Jul 2, 2025 | $67k |
| Jun 2, 2025 | Petersen Floyd F. Director | 500 0.00% of outstanding | $13k | Jun 2, 2025 | $54k |
| May 1, 2025 | Petersen Floyd F. Director | 500 0.00% of outstanding | $12k | May 1, 2025 | $42k |
| Apr 1, 2025 | Petersen Floyd F. Director | 500 0.00% of outstanding | $14k | Apr 1, 2025 | $28k |
| Mar 6, 2025 | Petersen Floyd F. Director | 1,000 0.00% of outstanding | $28k | Mar 6, 2025 | none |
| Mar 4, 2025 | PETERS WILLIAM J Officer | 4,231 0.01% of outstanding | $115k | Mar 4, 2025 | none |
| Dec 9, 2024 | Richard Prins Executive | 10,000 0.02% of outstanding | $440k | Dec 9, 2024 | $244k |
| Nov 12, 2024 | Richard Prins Director | 5,000 0.01% of outstanding | $241k | Nov 12, 2024 | none |
| Nov 12, 2024 | Rong Zhou Executive Vice President | 31,680 0.07% of outstanding | $1.5M | Nov 12, 2024 | $338k |
| Nov 6, 2024 | PETERS WILLIAM J Officer | 7,426 0.02% of outstanding | $387k | Nov 6, 2024 | none |
| Nov 6, 2024 | Liawatidewi Yakob Director | 5,214 0.01% of outstanding | $271k | Nov 6, 2024 | none |
Transactions
The newest 50 of 151 rows filed, every code.
| Date | Insider | Transaction | Shares | Price | Value | Holdings after | Filed |
|---|---|---|---|---|---|---|---|
| Sep 21, 2026 | William J Peters CFO, EVP & TREASURER | SOpen-market sale Common Stock10b5-1 | -4,139 | $25.00 | $103k | 168,707 | 20 d ago |
| Sep 16, 2026 | Rong Zhou SENIOR EVP, PRODUCTION CENTER | MOption exercise Common Stock | +10,000 | $13.35 | $134k | 179,203 | 26 d ago |
| Sep 16, 2026 | Rong Zhou SENIOR EVP, PRODUCTION CENTER | SOpen-market sale Common Stock | -10,000 | $23.94 | $239k | 169,203 | 26 d ago |
| Sep 16, 2026 | Rong Zhou SENIOR EVP, PRODUCTION CENTER | MOption exercise Employee Stock Option (right to buy)derivative | -10,000 | $0.00 | $0 | 19,424 | 26 d ago |
| Sep 2, 2026 | Rong Zhou SENIOR EVP, PRODUCTION CENTER | SOpen-market sale Common Stock | -3,187 | $23.63 | $75k | 169,203 | 40 d ago |
| Aug 19, 2024 | Richard K Prins director | GGift Common Stock | -1,500 | $0.00 | $0 | 29,455 | Jun 3, 2026 |
| Jun 1, 2026 | Howard Lee director | AGrant or award Common Stock | +8,143 | $0.00 | $0 | 160,119 | Jun 3, 2026 |
| Jun 1, 2026 | Diane G. Gerst director | AGrant or award Common Stock | +8,143 | $0.00 | $0 | 31,899 | Jun 3, 2026 |
| Jun 1, 2026 | David Russell Gaugh director | AGrant or award Common Stock | +8,143 | $0.00 | $0 | 14,447 | Jun 3, 2026 |
| Jun 1, 2026 | Michael A Zasloff director | AGrant or award Common Stock | +8,143 | $0.00 | $0 | 37,667 | Jun 3, 2026 |
| Jun 1, 2026 | Gayle Deflin director | AGrant or award Common Stock | +8,143 | $0.00 | $0 | 19,057 | Jun 3, 2026 |
| Jun 1, 2026 | Michael A Zasloff director | AGrant or award Common Stockderivative | +17,365 | $0.00 | $0 | 17,365 | Jun 3, 2026 |
| Jun 1, 2026 | Richard K Prins director | AGrant or award Common Stock | +8,143 | $0.00 | $0 | 37,598 | Jun 3, 2026 |
| Jun 1, 2026 | David Russell Gaugh director | AGrant or award Stock Option (right to buy)derivative | +17,365 | $0.00 | $0 | 17,365 | Jun 3, 2026 |
| Jun 2, 2026 | Howard Lee director | FTax withholding Common Stock | -769 | $18.45 | $14k | 159,350 | Jun 3, 2026 |
| Jun 1, 2026 | Gayle Deflin director | AGrant or award Stock Option (right to buy)derivative | +17,365 | $0.00 | $0 | 17,365 | Jun 3, 2026 |
| Jun 1, 2026 | Diane G. Gerst director | AGrant or award Stock Option (right to buy)derivative | +17,365 | $0.00 | $0 | 17,365 | Jun 3, 2026 |
| Jun 1, 2026 | Richard K Prins director | AGrant or award Stock Option (right to buy)derivative | +17,365 | $0.00 | $0 | 17,365 | Jun 3, 2026 |
| Jun 1, 2026 | Howard Lee director | AGrant or award Stock Option (right to buy)derivative | +17,365 | $0.00 | $0 | 17,365 | Jun 3, 2026 |
| Mar 15, 2026 | Jack Y. Zhang CEO & CHIEF SCIENTIFIC OFFICER | FTax withholding Common Stock | -9,784 | $18.18 | $178k | 2,990,052 | Mar 17, 2026 |
| Mar 15, 2026 | William J Peters CFO, EVP & TREASURER | FTax withholding Common Stock | -1,973 | $18.18 | $36k | 175,063 | Mar 17, 2026 |
| Mar 15, 2026 | Rong Zhou SENIOR EVP, PRODUCTION CENTER | FTax withholding Common Stock | -1,225 | $18.18 | $22k | 171,554 | Mar 17, 2026 |
| Mar 15, 2026 | Yakob Liawatidewi EVP CORP ADMIN CENTER | FTax withholding Common Stock | -1,033 | $18.18 | $19k | 121,892 | Mar 17, 2026 |
| Mar 15, 2026 | Jack Y. Zhang CEO & CHIEF SCIENTIFIC OFFICER | FTax withholding Common Stockindirect: See footnote | -2,908 | $18.18 | $53k | 1,245,125 | Mar 17, 2026 |
| Mar 9, 2026 | William J Peters CFO, EVP & TREASURER | AGrant or award Common Stock | +58,693 | $0.00 | $0 | 180,333 | Mar 11, 2026 |
| Mar 9, 2026 | Rong Zhou SENIOR EVP, PRODUCTION CENTER | AGrant or award Common Srock | +39,432 | $0.00 | $0 | 174,994 | Mar 11, 2026 |
| Mar 9, 2026 | Yakob Liawatidewi EVP CORP ADMIN CENTER | AGrant or award Common Stock | +35,450 | $0.00 | $0 | 124,795 | Mar 11, 2026 |
| Mar 9, 2026 | Jack Y. Zhang CEO & CHIEF SCIENTIFIC OFFICER | AGrant or award Common Stock | +180,504 | $0.00 | $0 | 3,014,621 | Mar 11, 2026 |
| Mar 10, 2026 | Jack Y. Zhang CEO & CHIEF SCIENTIFIC OFFICER | FTax withholding Common Stock | -14,785 | $18.91 | $280k | 2,999,836 | Mar 11, 2026 |
| Mar 10, 2026 | William J Peters CFO, EVP & TREASURER | FTax withholding Common Stock | -3,297 | $18.91 | $62k | 177,036 | Mar 11, 2026 |
| Mar 10, 2026 | Rong Zhou SENIOR EVP, PRODUCTION CENTER | FTax withholding Common Stock | -2,215 | $18.91 | $42k | 172,779 | Mar 11, 2026 |
| Mar 10, 2026 | Yakob Liawatidewi EVP CORP ADMIN CENTER | FTax withholding Common Stock | -1,870 | $18.91 | $35k | 122,925 | Mar 11, 2026 |
| Mar 9, 2026 | William J Peters CFO, EVP & TREASURER | AGrant or award Employee Stock Option (right to buy)derivative | +121,071 | $0.00 | $0 | 121,071 | Mar 11, 2026 |
| Mar 9, 2026 | Jack Y. Zhang CEO & CHIEF SCIENTIFIC OFFICER | AGrant or award Common Stockindirect: See footnote | +72,462 | $0.00 | $0 | 1,252,428 | Mar 11, 2026 |
| Mar 9, 2026 | Yakob Liawatidewi EVP CORP ADMIN CENTER | AGrant or award Employee Stock Option (right to buy)derivative | +73,126 | $0.00 | $0 | 73,126 | Mar 11, 2026 |
| Mar 10, 2026 | Jack Y. Zhang CEO & CHIEF SCIENTIFIC OFFICER | FTax withholding Common Stockindirect: See footnote | -4,395 | $18.91 | $83k | 1,248,033 | Mar 11, 2026 |
| Mar 9, 2026 | Rong Zhou SENIOR EVP, PRODUCTION CENTER | AGrant or award Employee Stock Option (right to buy)derivative | +81,341 | $0.00 | $0 | 81,341 | Mar 11, 2026 |
| Mar 9, 2026 | Jack Y. Zhang CEO & CHIEF SCIENTIFIC OFFICER | AGrant or award Employee Stock Option (right to buy)derivative | +372,338 | $0.00 | $0 | 372,338 | Mar 11, 2026 |
| Mar 9, 2026 | Jack Y. Zhang CEO & CHIEF SCIENTIFIC OFFICER | AGrant or award Employee Stock Option (right to buy)derivativeindirect: See footnote | +149,472 | $0.00 | $0 | 149,472 | Mar 11, 2026 |
| Mar 6, 2026 | Jack Y. Zhang CEO & CHIEF SCIENTIFIC OFFICER | FTax withholding Common Stock | -7,773 | $19.34 | $150k | 2,834,117 | Mar 10, 2026 |
| Mar 6, 2026 | William J Peters CFO, EVP & TREASURER | FTax withholding Common Stock | -2,146 | $19.34 | $42k | 121,640 | Mar 10, 2026 |
| Mar 6, 2026 | Rong Zhou SENIOR EVP, PRODUCTION CENTER | FTax withholding Common Stock | -1,357 | $19.34 | $26k | 135,562 | Mar 10, 2026 |
| Mar 6, 2026 | Yakob Liawatidewi EVP CORP ADMIN CENTER | FTax withholding Common Stock | -1,144 | $19.34 | $22k | 89,345 | Mar 10, 2026 |
| Mar 6, 2026 | Jack Y. Zhang CEO & CHIEF SCIENTIFIC OFFICER | FTax withholding Common Stockindirect: See footnote | -3,077 | $19.34 | $60k | 1,179,966 | Mar 10, 2026 |
| Mar 4, 2026 | Jack Y. Zhang CEO & CHIEF SCIENTIFIC OFFICER | FTax withholding Common Stock | -5,769 | $19.96 | $115k | 2,841,890 | Mar 6, 2026 |
| Mar 4, 2026 | William J Peters CFO, EVP & TREASURER | FTax withholding Common Stock | -1,744 | $19.96 | $35k | 123,786 | Mar 6, 2026 |
| Mar 4, 2026 | Rong Zhou SENIOR EVP, PRODUCTION CENTER | FTax withholding Common Stock | -1,124 | $19.96 | $22k | 136,919 | Mar 6, 2026 |
| Mar 4, 2026 | Yakob Liawatidewi EVP CORP ADMIN CENTER | FTax withholding Common Stock | -965 | $19.96 | $19k | 90,489 | Mar 6, 2026 |
| Mar 4, 2026 | Jack Y. Zhang CEO & CHIEF SCIENTIFIC OFFICER | FTax withholding Common Stockindirect: See footnote | -2,432 | $19.96 | $49k | 1,183,043 | Mar 6, 2026 |
| Dec 17, 2025 | Rong Zhou SENIOR EVP, PRODUCTION CENTER | MOption exercise Common Stock | +9,787 | $11.33 | $111k | 147,830 | Dec 18, 2025 |
Insiders
Everyone who has filed a Form 4 here.
- Gayle Deflindirector
- David Russell Gaughdirector
- Diane G. Gerstdirector
- Howard Leedirector
- Yakob LiawatidewiEVP CORP ADMIN CENTER
- William J PetersCFO, EVP & TREASURER
- Richard K Prinsdirector
- Floyd F. Petersendirector
- Michael A Zasloffdirector
- Jack Y. ZhangCEO & CHIEF SCIENTIFIC OFFICER
- Rong ZhouSENIOR EVP, PRODUCTION CENTER
Questions about AMPH
Answered from the filings on this page, as of the latest one.
Are insiders buying AMPH?
As of Sep 23, 2026, SEC Form 4 filings show 0 open-market buys worth $0 by 0 insiders and 3 open-market sells worth $418k by 2 insiders at Amphastar Pharmaceuticals, Inc. in the last 90 days, net -$418k. Only purchases (code P) and sales (code S) count; grants, option exercises and tax withholding do not.
Who was the last insider to trade AMPH on the open market?
William J Peters (CFO, EVP & TREASURER) sold $103k of AMPH on Sep 21, 2026 and filed the Form 4 on Sep 23, 2026. InsiderTell scored 20 (weak), under a 10b5-1 plan, with 2 insiders on the same side within 14 days.
How many insiders file Form 4 at Amphastar Pharmaceuticals, Inc.?
11 people have filed a Form 4 at Amphastar Pharmaceuticals, Inc., among them Gayle Deflin (director), David Russell Gaugh (director), Diane G. Gerst (director). Officers, directors and holders of more than 10% of a share class must report their trades within two business days.
Not investment advice. Scores and forward returns are decision support built from public SEC filings and past prices; they describe what happened after comparable filings, not what will happen after this one. Do your own research and size your risk.