Skip to content
Insider tapeFilings through Fri, Oct 9
Watchlist
AMPH

Amphastar Pharmaceuticals (AMPH) stock: insider trades, news & valuation

Heavy selling
Close · Oct 9, 2026 $26.62 +3.1% on the day +6.6% over 12 months 52-week range $16.87 – $29.40

Share price and insider trades

AMPH closeInsider buyInsider sale
15202530NovDecJan 2026FebMarAprMayJunJulAugSepOctEEarnings release filed 2025-11-06EEarnings release filed 2026-02-26EEarnings release filed 2026-05-07EEarnings release filed 2026-08-06Sold $12,635 on 2025-11-03 · Floyd F. PetersenSold $44,624 on 2025-12-11 · Floyd F. PetersenSold $62,882 on 2025-12-12 · Floyd F. PetersenSold $75,309 on 2026-09-02 · Rong ZhouSold $103,475 on 2026-09-21 · William J PetersSold $113,251 on 2025-11-25 · Richard K PrinsSold $161,852 on 2026-08-11 · Richard K PrinsSold $183,886 on 2026-08-07 · William J PetersSold $239,400 on 2026-09-16 · Rong ZhouSold $256,419 on 2025-12-17 · Rong ZhouSold $441,827 on 2025-11-13 · Floyd F. Petersen
Bought, 12 months$0
Sold, 12 months$1.7M
Insiders buying0
Insiders selling4

Amphastar Pharmaceuticals insider trading at a glance (Oct 9, 2026): in the past 12 months, 0 insiders bought $0 and 4 sold $1.7M of AMPH stock on the open market.

AMPH insider buying and selling by quarter

Open-market purchases (green, above the line) and sales (red, below), by trade date.

Q4 2025: $945K sold (7 trades)Q4 2025Q1 2026Q2 2026Q3 2026: $764K sold (5 trades)Q3 2026Q4 2026
QuarterBoughtPurchasesSoldSales
Q4 2026—0—0
Q3 2026—0$764K5
Q2 2026—0—0
Q1 2026—0—0
Q4 2025—0$945K7

Valuation, profit and volume

P/E (trailing)n/aSector median —
Market value— 
Profit margin—Revenue growth —
Volume vs. 50-day1.1×Last 5 sessions
Insiders' paper profit—On all tracked purchases —

Summary

Over the past 12 months, 0 Amphastar Pharmaceuticals, Inc. insiders reported open-market purchases totaling $0, while 4 insiders reported sales totaling $1.7M. 4 of 12 recorded sales were made under pre-scheduled Rule 10b5-1 trading plans, which are usually less informative than discretionary sales.

AMPH earnings: how the stock reacted

Each quarterly results release (SEC 8-K Item 2.02), the trend before it, insider trades in the 30 days before, and the 2-day market reaction. “E” marks releases on the chart above.

Does it matter? →
Release15 days beforeInsiders, 30 days beforeReaction (2 days)Next 30 days
Aug 6, 2026 +3.3% None +2.7%S&P +0.5% +11.5%
May 7, 2026 +12.7% None -20.5%S&P +0.5% +3.9%
Feb 26, 2026 -2.1% None -27.7%S&P -1.0% -6.0%
Nov 6, 2025 +4.3% Sold $13K -5.1%S&P -1.0% +11.4%
Aug 7, 2025 -2.5% None +14.4%S&P +0.7% +23.6%
May 7, 2025 +1.6% None +3.3%S&P +1.1% +5.4%
Feb 27, 2025 -3.1% None -8.9%S&P -0.1% +0.0%
Nov 6, 2024 +1.5% None -10.6%S&P +3.3% -5.0%

Most companies bar insiders from trading in the weeks before results, so pre-earnings purchases are rare and often made by directors or under pre-set plans. Past reactions don't predict future ones.

Insider transactions

Open-market purchases and sales.

Filed Insider Type Shares Price Value Since Score
Sep 23SEC William J PetersCFO Sell Plan 4,139168,707 held (−2%) $25.00 $103K +6.5% —
Sep 17SEC Rong ZhouSenior Evp, Production Center Sell 10,000169,203 held (−6%) $23.94 $239K +11.2% —
Sep 3SEC Rong ZhouSenior Evp, Production Center Sell 3,187169,203 held (−2%) $23.63 $75K +12.7% —
Aug 12SEC Richard K PrinsDirector Sell 7,97329,625 held (−21%) $20.30 $162K +31.1% —
Aug 11SEC William J PetersCFO Sell Plan 8,180172,846 held (−5%) $22.48 $184K +18.4% —
Dec 18SEC Rong ZhouSenior Evp, Production Center Sell 9,787138,043 held (−7%) $26.20 $256K +1.6% —
Dec 15SEC Floyd F. PetersenDirector Sell 2,42671,368 held (−3%) $25.92 $63K +2.7% —
Dec 15SEC Floyd F. PetersenDirector Sell 1,73773,794 held (−2%) $25.69 $45K +3.6% —
Nov 25SEC Richard K PrinsDirector Sell 4,17935,183 held (−11%) $27.10 $113K -1.8% —
Nov 17SEC Floyd F. PetersenDirector Sell 16,67975,531 held (−18%) $26.49 $442K +0.5% —
Nov 5SEC Floyd F. PetersenDirector Sell Plan 50075,531 held (−1%) $25.27 $13K +5.3% —
Oct 2SEC Floyd F. PetersenDirector Sell Plan 50076,031 held (−1%) $27.20 $14K -2.1% —

Insiders at Amphastar Pharmaceuticals, Inc.

InsiderBoughtSoldLast filingScore
Floyd F. PetersenDirector — $576K Dec 15, 2025 —
Rong ZhouSenior Evp, Production Center — $571K Sep 17, 2026 —
William J PetersCFO — $287K Sep 23, 2026 —
Richard K PrinsDirector — $275K Aug 12, 2026 —

AMPH stock: common questions

Are Amphastar Pharmaceuticals, Inc. insiders buying AMPH stock?

In the past 12 months, 0 insiders reported open-market purchases of AMPH worth $0.

Are Amphastar Pharmaceuticals, Inc. insiders selling AMPH stock?

4 insiders reported sales worth $1.7M over the same period.

Where does this data come from?

Every transaction comes from Form 4 filings that insiders must submit to the SEC within two business days of a trade. We pull them from SEC EDGAR every night.

What is AMPH's 52-week range?

Over the past year AMPH has traded between $16.87 and $29.40. It last closed at $26.62 on Oct 9, 2026.