Constantin Ionel Stefan sold $2.1M of AMPX
Chief Technology Officer at Amprius Technologies, Inc.. 198,255 shares at an average of $10.51, traded Dec 11, 2025, filed Dec 15, 2025.
Score components
- +15RoleOfficer
- +25Trade size$2.1M at market
- +5Share of holdings soldSold 21% of holdings
- 0ClusterNo other insider selling within 14 days
- -15Exercise and sellShares came from an option exercise in the same filing
- -2010b5-1 planPre-scheduled under a 10b5-1 plan
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.
This signal so far: 1m +3.1%, 3m +86.0%, 6m +67.4%.
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.
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 0001940928-25-000020, as filed. Open on EDGAR
| Date | Transaction | Shares | Price | Value | Holdings after | Filed |
|---|---|---|---|---|---|---|
| Dec 11, 2025 | MOption exercise Common stock10b5-1 | +125,000 | $0.05 | $6,250 | 946,951 | Dec 15, 2025 |
| Dec 11, 2025 | SOpen-market sale Common stock10b5-1 | -198,255 | $10.51 | $2.1M | 748,696 | Dec 15, 2025 |
| Dec 11, 2025 | MOption exercise Stock Option (right to buy)derivative10b5-1 | -125,000 | $0.00 | $0 | 310,962 | Dec 15, 2025 |
Related signals
Other insiders at Amprius Technologies, Inc. and this insider’s other filings.
| Score | Company | Insider | Value | Holdings | Filed |
|---|---|---|---|---|---|
| 50Moderate | Amprius Technologies, Inc. | Kang Sun Chief Executive Officer | $642k 62,101 shares | -5% | |
| 44Moderate | Amprius Technologies, Inc. | Constantin Ionel Stefan Chief Technology Officer | $307k 29,681 shares | -4% | |
| 54Moderate | Amprius Technologies, Inc. | Thomas M Stepien Chief Executive Officer | $324k 31,529 shares | -5% | |
| 53Moderate | Amprius Technologies, Inc. | Donald R Dixon director | $1.5M 85,000 shares | -19% | |
| 52Moderate | Amprius Technologies, Inc. | Donald R Dixon director | $765k 40,000 shares | -8% | |
| 46Moderate | Amprius Technologies, Inc. | Thomas M Stepien Chief Executive Officer | $42k 2,000 shares | -0% | |
| 44Moderate | Amprius Technologies, Inc. | Donald R Dixon director | $320k 17,895 shares | -4% | |
| 30Weak | Amprius Technologies, Inc. | Kang Sun Chief Executive Officer | $6,121 356 shares | -0% | |
| 37Weak | Amprius Technologies, Inc. | Constantin Ionel Stefan Chief Technology Officer | $55k 3,208 shares | -0% | |
| 48Moderate | Amprius Technologies, Inc. | Thomas M Stepien Chief Executive Officer | $75k 4,375 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.