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sellWeak cluster of 2

Constantin Ionel Stefan sold $258k of AMPX

Chief Technology Officer at Amprius Technologies, Inc.. 25,366 shares at an average of $10.16, traded Feb 23, 2026, filed Feb 24, 2026.

Warning score
36
Value
$258k
25,366 shares
Holdings after
723,330
-3% from before
From 52-week low
+473%
low $1.78, close $10.20
From 52-week high
-31%
high $14.68, as of Feb 23, 2026

Score components

  • Role
    Officer
    +15
  • Trade size
    $258k at market
    +13
  • Share of holdings sold
    Sold 3.4% of holdings
    0
  • Cluster
    2 insiders selling within 14 days
    +8

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 Feb 24, 2026: -12.6%SPY +14.2% · excess -26.7%

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 0001940928-26-000009, as filed. Open on EDGAR

DateTransactionSharesPriceValueHoldings afterFiled
Feb 23, 2026SOpen-market sale
Common stock
-25,366$10.16$258k723,330Feb 24, 2026

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 $258k of AMPX | InsiderTell