Constantin Ionel Stefan
CIK 1940928 · View on SEC EDGAR ↗
Insider
First SEC filing: May 28, 2026 · Latest: May 28, 2026
On this page
Insider at
Insider transactions
0 buys (P)
2 sells (S)
Net:
$-481,240
+ 5 non-open-market transactions below
last 12 months, based on the transactions shown below
Price change vs current quote, split-adjusted for corporate actions since the filing — not benchmarked, not annualized, not size-weighted
5 other filings hidden
| Date | Ticker | Code | Shares | Price | Value | Owned after | Δ own | A/D | vs now |
|---|---|---|---|---|---|---|---|---|---|
| May 27, 2026 | AMPX | S | 3,208 | $17.19 | $55,157 | 801,310 | — | — | -39.5% (price as of 2026-08-21) |
| May 21, 2026 | AMPX | S | 28,812 | $14.79 | $426,083 | 804,518 | — | — | -29.7% (price as of 2026-08-21) |
P = Open-market purchase · S = Sale · A = Grant/award · M = Option exercise · G = Gift · F = Tax withholding
Insider transactions are not a recommendation; sales are often driven by liquidity or tax reasons.
Derivative holdings (Form 4 Table II)
Options, RSUs and convertible securities reported on Form 4 Table II.
| Date | Ticker | Security | Underlying | Exercise price | Expiration | Shares | A/D |
|---|---|---|---|---|---|---|---|
| Sept. 14, 2022 | AMPX | Stock Option (right to buy) | Common Stock (218,385) | $2.61 | April 13, 2032 | 218,385 | Acquired |
| Sept. 14, 2022 | AMPX | Stock Option (right to buy) | Common Stock (72,795) | $1.78 | June 16, 2031 | 72,795 | Acquired |
| Sept. 14, 2022 | AMPX | Stock Option (right to buy) | Common Stock (72,795) | $0.45 | March 19, 2028 | 72,795 | Acquired |
| Sept. 14, 2022 | AMPX | Stock Option (right to buy) | Common Stock (181,987) | $0.05 | July 11, 2027 | 181,987 | Acquired |
| Sept. 14, 2022 | AMPX | Stock Option (right to buy) | Common Stock (545,962) | $0.05 | March 15, 2024 | 545,962 | Acquired |
Exercise/conversion price is blank when not applicable (e.g. RSUs).