Insider trades › Stefan Constantin Ionel
Stefan Constantin Ionel
A corporate insider: an officer, director or owner of more than 10% of a company. Insiders report their trades to the SEC on Form 4The form insiders use to report each purchase or sale of their company's stock. It is due within two business days of the trade. · Last filing Aug 25, 2026
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Using 13F.ai, list Stefan Constantin Ionel's open-market buys and sells across companies in the last two years, with the Form 4 links.
Using 13F.ai, how did the stocks Stefan Constantin Ionel bought perform after the purchase compared with the S&P 500?
Using 13F.ai, are other insiders at the same companies buying or selling at the same time as Stefan Constantin Ionel?
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Buying and selling by quarter
Dollars bought and sold on the open market over the last two years.
Bought Sold
By trade date, using the shares and price reported for each trade. Stock grants, option exercises and shares withheld for tax are left out.
Roles
The companies where this person reports as an insider, and their position at each, most recent first.
| Company | Role | Last filed |
|---|---|---|
| AMPX Amprius Technologies, Inc. | Chief Technology Officer | Aug 25, 2026 |
Roles come from the filings themselves and can change over time.
Latest open-market trades
Purchases and sales at every company, most recent filing first.
| How the stock has done since the trade date, measured against the S&P 500 over the same days. It describes the stock, not the trader's actual gain or loss. | Filing | ||||||
|---|---|---|---|---|---|---|---|
| Aug 21, 2026 | AMPX Amprius Technologies, Inc. | Sale | 29,681 | $10.34 | $306.9K | -21.8% | Form 4 ↗ |
| May 27, 2026 | AMPX Amprius Technologies, Inc. | Sale | 3,208 | $17.19 | $55.1K | -54.3% | Form 4 ↗ |
| May 21, 2026 | AMPX Amprius Technologies, Inc. | Sale | 28,812 | $14.79 | $426.1K | -49.7% | Form 4 ↗ |
| Feb 23, 2026 | AMPX Amprius Technologies, Inc. | Sale | 25,366 | $10.16 | $257.7K | -32.8% | Form 4 ↗ |
| Jan 28, 2026 | AMPX Amprius Technologies, Inc. | Sale | 39,690 | $12.00 | $476.3K | -42.3% | Form 4 ↗ |
| Jan 23, 2026 | AMPX Amprius Technologies, Inc. | Sale | 1,600 | $12.00 | $19.2K | -38.5% | Form 4 ↗ |
| Jan 22, 2026 | AMPX Amprius Technologies, Inc. | Sale | 492,827 | $12.04 | $5.9M | -43.1% | Form 4 ↗ |
| Jan 21, 2026 | AMPX Amprius Technologies, Inc. | Sale | 73,280 | $12.00 | $879.4K | -39.7% | Form 4 ↗ |
| Dec 11, 2025 | AMPX Amprius Technologies, Inc. | Sale | 198,255 | $10.51 | $2.1M | -40.1% | Form 4 ↗ |
| Nov 21, 2025 | AMPX Amprius Technologies, Inc. | Sale | 25,024 | $10.08 | $252.2K | -36.0% | Form 4 ↗ |
| Aug 21, 2025 | AMPX Amprius Technologies, Inc. | Sale | 19,159 | $6.82 | $130.7K | -1.9% | Form 4 ↗ |
| May 21, 2025 | AMPX Amprius Technologies, Inc. | Sale | 20,366 | $2.43 | $49.5K | +198.3% | Form 4 ↗ |
| Feb 21, 2025 | AMPX Amprius Technologies, Inc. | Sale | 9,066 | $3.13 | $28.4K | +138.6% | Form 4 ↗ |
| Nov 21, 2024 | AMPX Amprius Technologies, Inc. | Sale | 8,575 | $1.96 | $16.8K | +273.4% | Form 4 ↗ |
Each row links to its Form 4. Since trade compares the stock’s move from the close on the trade date (or the next trading day) to its latest close with the S&P 500 over the same days, adjusted for splits and excluding dividends. It describes the stock, not what the trader made: we don’t know their purchase price, position size or later sales. A dash means the trade isn’t matched to a listed stock, or there is no closing price after it yet.
When several people report on the same filing, we list it under the first one named, so trades by someone usually listed second may be missing here. Information, not investment advice: see the disclaimer.