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sellWeak cluster of 210b5-1 plan

William J Peters sold $103k of AMPH

CFO, EVP & TREASURER at Amphastar Pharmaceuticals, Inc.. 4,139 shares at an average of $25.00, traded Sep 21, 2026, filed Sep 23, 2026.

Warning score
20
Value
$103k
4,139 shares
Holdings after
168,707
-2% from before
From 52-week low
+45%
low $16.87, close $24.48
From 52-week high
-17%
high $29.40, as of Sep 21, 2026

Score components

  • Role
    CFO
    +22
  • Trade size
    $103k at market
    +10
  • Share of holdings sold
    Sold 2.4% of holdings
    0
  • Cluster
    2 insiders selling within 14 days
    +8
  • 10b5-1 plan
    Pre-scheduled under a 10b5-1 plan
    -20

What happened after comparable sells

Same side and tier, against the S&P 500, at 1, 3 and 6 months. Shown to Pro users; the whole table is on the backtest page.

Price around the trade, and since

From a quarter before the trade to today. The arrow is the trade, the circle the day the filing reached EDGAR, which is the first day anyone outside could act; the dotted line is the S&P 500 rebased to that day's close.

AMPHOct 9, 2026 · close 26.62
Since filing Sep 23, 2026: +6.7%SPY +1.4% · excess +5.2%

Daily candles, adjusted for splits and dividends. Green arrows are insider buys, red are sells, sized by value; the dashed line is the close on the filing day, the dotted line SPY rebased to it.Charts by TradingView Lightweight Charts™

Rows in this filing

Every transaction in Form 4 0001263136-26-000014, as filed. Open on EDGAR

DateTransactionSharesPriceValueHoldings afterFiled
Sep 21, 2026SOpen-market sale
Common Stock10b5-1
-4,139$25.00$103k168,70720 d ago

Related signals

Other insiders at Amphastar Pharmaceuticals, Inc. and this insider’s other filings.

ScoreCompanyInsiderValueHoldingsFiled
21Weak
AMPHsell 2
Amphastar Pharmaceuticals, Inc.
Rong Zhou
SENIOR EVP, PRODUCTION CENTER
$239k
10,000 shares
-6%
23Weak
AMPHsell
Amphastar Pharmaceuticals, Inc.
Rong Zhou
SENIOR EVP, PRODUCTION CENTER
$75k
3,187 shares
-2%
21Weak
AMPHsell 2
Amphastar Pharmaceuticals, Inc.
Rong Zhou
SENIOR EVP, PRODUCTION CENTER
$256k
9,787 shares
-7%
33Weak
AMPHsell 2
Amphastar Pharmaceuticals, Inc.
Floyd F. Petersen
director
$108k
4,163 shares
-6%
23Weak
AMPHsell 2
Amphastar Pharmaceuticals, Inc.
Richard K Prins
director
$113k
4,179 shares
-11%
30Weak
AMPHsell 2
Amphastar Pharmaceuticals, Inc.
Floyd F. Petersen
director
$442k
16,679 shares
-18%
0Weak
AMPHsell10b5-1
Amphastar Pharmaceuticals, Inc.
Floyd F. Petersen
director
$13k
500 shares
-1%
0Weak
AMPHsell10b5-1
Amphastar Pharmaceuticals, Inc.
Floyd F. Petersen
director
$14k
500 shares
-1%
0Weak
AMPHsell10b5-1
Amphastar Pharmaceuticals, Inc.
Floyd F. Petersen
director
$15k
500 shares
-1%
0Weak
AMPHsell10b5-1
Amphastar Pharmaceuticals, Inc.
Floyd F. Petersen
director
$10k
500 shares
-1%

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.