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sellModerate cluster of 3

Constantin Ionel Stefan sold $131k of AMPX

Chief Technology Officer at Amprius Technologies, Inc.. 19,159 shares at an average of $6.82, traded Aug 21, 2025, filed Aug 25, 2025.

Warning score
41
Value
$131k
19,159 shares
Holdings after
846,975
-2% from before
From 52-week low
+738%
low $0.81, close $6.79
From 52-week high
-22%
high $8.66, as of Aug 21, 2025

Score components

  • Role
    Officer
    +15
  • Trade size
    $131k at market
    +11
  • Share of holdings sold
    Sold 2.2% of holdings
    0
  • Cluster
    3 insiders selling within 14 days
    +15

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.

AMPXOct 9, 2026 · close 9.44
Since filing Aug 25, 2025: +22.9%SPY +22.8% · excess +0.1%

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 0001940928-25-000014, as filed. Open on EDGAR

DateTransactionSharesPriceValueHoldings afterFiled
Aug 21, 2025SOpen-market sale
Common stock
-19,159$6.82$131k846,975Aug 25, 2025

Related signals

Other insiders at Amprius Technologies, Inc. and this insider’s other filings.

ScoreCompanyInsiderValueHoldingsFiled
53Moderate
AMPXsell 2
Amprius Technologies, Inc.
Donald R Dixon
director
$1.5M
85,000 shares
-19%
52Moderate
AMPXsell 4
Amprius Technologies, Inc.
Donald R Dixon
director
$765k
40,000 shares
-8%
46Moderate
AMPXsell 4
Amprius Technologies, Inc.
Thomas M Stepien
Chief Executive Officer
$42k
2,000 shares
-0%
44Moderate
AMPXsell 4
Amprius Technologies, Inc.
Donald R Dixon
director
$320k
17,895 shares
-4%
30Weak
AMPXsell 4
Amprius Technologies, Inc.
Kang Sun
Chief Executive Officer
$6,121
356 shares
-0%
37Weak
AMPXsell 4
Amprius Technologies, Inc.
Constantin Ionel Stefan
Chief Technology Officer
$55k
3,208 shares
-0%
48Moderate
AMPXsell 4
Amprius Technologies, Inc.
Thomas M Stepien
Chief Executive Officer
$75k
4,375 shares
-1%
55Moderate
AMPXsell 4
Amprius Technologies, Inc.
Kang Sun
Chief Executive Officer
$1.0M
67,796 shares
-5%
47Moderate
AMPXsell 4
Amprius Technologies, Inc.
Constantin Ionel Stefan
Chief Technology Officer
$426k
28,812 shares
-3%
64Notable
AMPXsell 4
Amprius Technologies, Inc.
Thomas M Stepien
Chief Executive Officer
$898k
60,702 shares
-8%

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.

Constantin Ionel Stefan sold $131k of AMPX | InsiderTell