| Insider | Role | Shares | Value | Buys | Sells |
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| Date | Ticker | Insider | Role | Type | Shares | Price | Value | Chg% | SEC |
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| Insider | Role | Shares | Value | Buys | Sells |
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| Date | Ticker | Insider | Role | Type | Shares | Price | Value | Chg% | SEC |
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Chief Technology Officer
1 company
Constantin Ionel Stefan is Chief Technology Officer at AMPX. Constantin Ionel Stefan's net worth is not public. Form 4 filings only show shares in the companies where this person is an insider; those holdings are worth an estimated $6.8M at current prices.
Our model assigns Constantin Ionel Stefan a middling insider score of 52/100, based on 18 past trades. Over a 12-month horizon, 22.2% of those trades were profitable, with an average 12-month return of -50.4%.
The AMPX filings lean toward selling, a net 1,073,102 shares.
Constantin Ionel Stefan has 24 Form 4 filings on record from September 2022 to August 2026, all as Chief Technology Officer at Amprius Technologies, Inc. WT (AMPX), 2022–2026.
The 44 reported transactions were 19 open-market sales, 13 option exercises, 8 option or other derivative awards and 3 stock awards, plus smaller numbers of other types.
Counted by filing, the open-market trades come to no purchases and 15 sales worth about $11.2M.
The largest open-market sale was 567,707 shares of AMPX at an average $12.03 on January 23, 2026, about $6.8M.
None of the 15 sales since April 2023 was marked as made under a Rule 10b5-1 trading plan.
| Date | Ticker | Role | Type | Shares | Price | Value | Chg% | 3M | 12M | SEC |
|---|---|---|---|---|---|---|---|---|---|---|
| Aug 21, 2026 | AMPX Amprius Technologies, Inc. Wt | Chief Technology Officer | Sell | 29,681 | $10.34 | $306,931.22 | -3.7% | - | - | |
| May 27, 2026 | AMPX Amprius Technologies, Inc. Wt | Chief Technology Officer | Sell | 3,208 | $17.19 | $55,156.75 | -0.4% | -40.7% | - | |
| May 21, 2026 | AMPX Amprius Technologies, Inc. | Chief Technology Officer | Sell | 28,812 | $14.79 | $426,083.38 | -3.5% | -30.5% | - | |
| Feb 23, 2026 | AMPX Amprius Technologies, Inc. | Chief Technology Officer | Sell | 25,366 | $10.16 | $257,604.41 | -3.4% | +74.8% | - | |
| Jan 28, 2026 | AMPX Amprius Technologies, Inc. | Chief Technology Officer | Sale+OE | 39,690 | $12.00 | $476,351.44 | -5.0% | +64.4% | - | |
| Jan 23, 2026 | AMPX Amprius Technologies, Inc. | Chief Technology Officer | Sale+OE | 567,707 | $12.03 | $6,830,523.48 | -43.1% | +94.5% | - | |
| Dec 11, 2025 | AMPX Amprius Technologies, Inc. | Chief Technology Officer | Sale+OE | 198,255 | $10.51 | $2,083,382.49 | -20.9% | +62.5% | - | |
| Nov 21, 2025 | AMPX Amprius Technologies, Inc. | Chief Technology Officer | Sell | 25,024 | $10.08 | $252,274.45 | -3.0% | +2.4% | - | |
| Aug 21, 2025 | AMPX Amprius Technologies, Inc. | Chief Technology Officer | Sell | 19,159 | $6.82 | $130,591.58 | -2.2% | +59.2% | +52.3% | |
| May 21, 2025 | AMPX Amprius Technologies, Inc. | Chief Technology Officer | Sell | 20,366 | $2.43 | $49,530.11 | -2.3% | +178.5% | +532.2% |