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Amphastar Pharmaceuticals stock timeline
A year of the price with every insider trade, planned sale, earnings report and material 8-K marked
252 sessions+17.6% to $28.49
Amphastar Pharmaceuticals (AMPH) stock rose 18% over the last 252 sessions, to $28.49. On the way it reported 5 quarters, its insiders filed 8 open-market trades and 7 Form 144 notices of planned sales, and the company filed 4 material 8-Ks. Each is marked on the price and listed with what the stock did next.
Each mark, and what followed
| Date | Kind | What | Next session | 5 sessions | 21 sessions |
|---|---|---|---|---|---|
| Nov 5, 2026 | Earnings | Earnings: beat the EPS estimate by 32.8% | −1.3% (+3.2% vs SPY) | — | — |
| Nov 5, 2026 | Form 144 | Form 144: William J Peters plans to sell $366K | −1.3% (+3.2% vs SPY) | — | — |
| Nov 4, 2026 | Form 144 | Form 144: William J Peters plans to sell $448K | +3.3% (+1.6% vs SPY) | — | — |
| Sep 21, 2026 | Form 144 | Form 144: William J Peters plans to sell $103K | +3.6% (+2.0% vs SPY) | +10.1% (+8.9% vs SPY) | +10.2% (+9.5% vs SPY) |
| Sep 16, 2026 | Insider sale | Zhou Rong sold $239K | +1.3% (+1.7% vs SPY) | +2.8% (+0.5% vs SPY) | +9.8% (+8.0% vs SPY) |
| Sep 2, 2026 | Insider sale | Zhou Rong sold $75K | +3.3% (+2.9% vs SPY) | +0.3% (+0.3% vs SPY) | +9.9% (+9.4% vs SPY) |
| Sep 1, 2026 | Form 144 | Form 144: Rong Zhou plans to sell $290K | +1.9% (+2.6% vs SPY) | +1.8% (+1.9% vs SPY) | +13.6% (+13.9% vs SPY) |
| Aug 18, 2026 | Form 144 | Form 144: Floyd Petersen plans to sell $989K | +2.3% (+3.0% vs SPY) | +3.1% (+4.3% vs SPY) | +13.8% (+16.3% vs SPY) |
| Aug 11, 2026 | Form 144 | Form 144: Richard Prins plans to sell $162K | +0.5% (+0.9% vs SPY) | +2.7% (+2.7% vs SPY) | +12.6% (+14.0% vs SPY) |
| Aug 11, 2026 | Insider sale | Prins Richard K sold $162K | +0.5% (+0.9% vs SPY) | +2.7% (+2.7% vs SPY) | +12.6% (+14.0% vs SPY) |
| Aug 7, 2026 | Form 144 | Form 144: William J Peters plans to sell $184K | +4.8% (+4.2% vs SPY) | +1.8% (+0.6% vs SPY) | +15.7% (+15.5% vs SPY) |
| Aug 6, 2026 | Earnings | Earnings: beat the EPS estimate by 48.3% | −2.1% (−2.0% vs SPY) | −1.3% (−1.6% vs SPY) | +16.4% (+15.9% vs SPY) |
| Jul 13, 2026 | 8-K | Directors and officers: departures, appointments, pay | +3.0% (+3.8% vs SPY) | +5.3% (+6.9% vs SPY) | +8.1% (+5.8% vs SPY) |
| May 7, 2026 | Earnings | Earnings: missed the EPS estimate by -40.5% | +0.5% (+0.8% vs SPY) | −26.6% (−27.7% vs SPY) | −19.1% (−19.7% vs SPY) |
| Mar 6, 2026 | 8-K | Material definitive agreement | −0.7% (−1.5% vs SPY) | −6.2% (−4.7% vs SPY) | +6.2% (+7.9% vs SPY) |
| Mar 6, 2026 | 8-K | Directors and officers: departures, appointments, pay | −0.7% (−1.5% vs SPY) | −6.2% (−4.7% vs SPY) | +6.2% (+7.9% vs SPY) |
| Feb 26, 2026 | Earnings | Earnings: missed the EPS estimate by -20.5% | −5.4% (−4.9% vs SPY) | −33.8% (−32.6% vs SPY) | −35.9% (−29.0% vs SPY) |
| Jan 12, 2026 | 8-K | Material definitive agreement | −1.7% (−1.5% vs SPY) | −12.5% (−9.9% vs SPY) | −2.8% (−2.3% vs SPY) |
| Dec 17, 2025 | Insider sale | Zhou Rong sold $256K | +1.8% (+2.9% vs SPY) | +3.2% (+1.6% vs SPY) | +1.8% (−0.4% vs SPY) |
| Dec 12, 2025 | Insider sale | Petersen Floyd F. sold $63K | −2.5% (−1.4% vs SPY) | +2.3% (+4.2% vs SPY) | +11.0% (+10.0% vs SPY) |
| Dec 11, 2025 | Insider sale | Petersen Floyd F. sold $45K | +0.7% (+0.5% vs SPY) | +1.4% (+3.8% vs SPY) | +13.4% (+12.0% vs SPY) |
| Nov 25, 2025 | Insider sale | Prins Richard K sold $113K | +3.6% (+2.7% vs SPY) | −0.2% (−2.0% vs SPY) | +0.4% (−3.1% vs SPY) |
| Nov 13, 2025 | Insider sale | Petersen Floyd F. sold $442K | −5.4% (−3.7% vs SPY) | −9.3% (−6.2% vs SPY) | −9.6% (−9.4% vs SPY) |
| Nov 6, 2025 | Earnings | Earnings: beat the EPS estimate by 12.7% | −4.4% (−3.3% vs SPY) | +9.5% (+8.6% vs SPY) | +5.6% (+4.4% vs SPY) |
Insiders’ record here
In the year on the chart, Amphastar Pharmaceuticals' insiders reported 0 open-market buys ($0) and 8 sales ($1.4M). Of the 5 old enough to score, 4 were followed by the stock doing what the trade implied over the next 63 sessions (beating SPY after a buy, lagging it after a sale); the median excess return after a buy was — and after a sale −21.8%.
Across the whole universe (19,782 scored trades), insider buys beat the market 46% of the time and sales were followed by a lagging stock 61% of the time; buys of $1M or more 39%. Every pattern →
What this kind of 8-K usually did
| Item | 8-Ks | Next session, median | Up next session | 21 sessions, median | Typical size |
|---|---|---|---|---|---|
| 1.01 Material definitive agreement | 23,525 | 0.0% | 51% | +1.0% | ±1.4% |
| 5.02 Directors and officers: departures, appointments, pay | 39,174 | −0.1% | 48% | +0.7% | ±1.4% |
Across every company in the move-odds universe, measured from the close before the filing. Every 8-K item ranked →
Report card: every quarter against the estimate → Amphastar Pharmaceuticals: every quarter → Live insider trades →
Prices are daily closes; filings and trades are as filed with the SEC (Form 4 within two business days of the trade, 8-K within four of the event). Moves after a mark are the stock's close-to-close change and the same for SPY; they describe the record, not what the next one will do. Not investment advice.