Skip to content
sellWeak cluster of 210b5-1 plan

William J Peters sold $184k of AMPH

CFO, EVP & TREASURER at Amphastar Pharmaceuticals, Inc.. 8,180 shares at an average of $22.48, traded Aug 7, 2026, filed Aug 11, 2026.

Warning score
7
Value
$184k
8,180 shares
Holdings after
172,846
-5% from before
From 52-week low
+23%
low $16.87, close $20.78
From 52-week high
-33%
high $30.81, as of Aug 7, 2026

Score components

  • Role
    CFO
    +22
  • Trade size
    $184k at market
    +12
  • Share of holdings sold
    Sold 4.5% of holdings
    0
  • Cluster
    2 insiders selling within 14 days
    +8
  • Exercise and sell
    Shares came from an option exercise in the same filing
    -15
  • 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 13, 2026 · close 26.05
Since filing Aug 11, 2026: +27.6%SPY +1.2% · excess +26.4%

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 0001263136-26-000012, as filed. Open on EDGAR

DateTransactionSharesPriceValueHoldings afterFiled
Aug 7, 2026MOption exercise
Common Stock10b5-1
+5,053$19.79$100k181,026Aug 11, 2026
Aug 7, 2026SOpen-market sale
Common Stock10b5-1
-8,180$22.48$184k172,846Aug 11, 2026
Aug 7, 2026MOption exercise
Employee Stock Option (right to buy)derivative10b5-1
-5,053$0.00$00Aug 11, 2026

Related signals

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

ScoreCompanyInsiderValueHoldingsFiled
20Weak
AMPHsell 210b5-1
Amphastar Pharmaceuticals, Inc.
William J Peters
CFO, EVP & TREASURER
$103k
4,139 shares
-2%
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%
39Weak
AMPHsell 2
Amphastar Pharmaceuticals, Inc.
Richard K Prins
director
$162k
7,973 shares
-21%
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%

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.

William J Peters sold $184k of AMPH | InsiderTell