As of September 29, 2026, the three largest insider holders of AMPX are Inc. Amprius, (TenPercentOwner, 2.50Mn shares), Justin E Mirro (Director, 2.39Mn shares), Kang Sun (Chief Executive Officer, 1.22Mn shares).
| # | Insider | Position | Direct | Indirect | Total | Share of Insiders | Last Filed |
|---|---|---|---|---|---|---|---|
| 1 | Justin E Mirro | Director | 0 | 3,588,042 | 3,588,042 | 29.9% | 05 Sep, 2024 |
| 2 | Inc. Amprius, | TenPercentOwner | 2,500,071 | 0 | 2,500,071 | 20.8% | 25 Oct, 2024 |
| 3 | Kang Sun | Chief Executive Officer | 1,218,397 | 0 | 1,218,397 | 10.2% | 25 Aug, 2026 |
| 4 | Sandra Wallach | Chief Financial Officer | 1,005,275 | 0 | 1,005,275 | 8.4% | 25 Aug, 2025 |
| 5 | Constantin Ionel Stefan | Chief Technology Officer | 771,629 | 0 | 771,629 | 6.4% | 25 Aug, 2026 |
| 6 | Donald R Dixon | Director | 280,079 | 359,380 | 639,459 | 5.3% | 16 Jun, 2026 |
| 7 | Thomas M Stepien | Chief Executive Officer | 578,750 | 37,260 | 616,010 | 5.1% | 25 Aug, 2026 |
| 8 | Jonathan Bornstein | President Of Amprius Lab | 422,668 | 0 | 422,668 | 3.5% | 12 Mar, 2025 |
| 9 | Ricardo C. Rodriguez | Chief Financial Officer | 350,000 | 0 | 350,000 | 2.9% | 13 Mar, 2026 |
| 10 | Livingston Satterthwaite | Director | 346,506 | 0 | 346,506 | 2.9% | 16 Jun, 2026 |
| 11 | Kathleen A Bayless | Director | 216,120 | 0 | 216,120 | 1.8% | 16 Jun, 2026 |
| 12 | Mary Gustanski | Director | 146,396 | 0 | 146,396 | 1.2% | 07 Jun, 2024 |
| 13 | Steven Chu | Director | 137,762 | 0 | 137,762 | 1.1% | 16 Jun, 2026 |
| 14 | Wen Hsuan Hsieh | Director | 44,444 | 0 | 44,444 | 0.4% | 13 Mar, 2026 |
Each row is that insider’s most recently reported position, from Form 4 filings over the last 60 months — which is why this total does not tie to the quarterly series above, where a quarter counts only the insiders who filed in it. Shares held through a fund or institutional portfolio are counted on the institutional ownership page instead.
| Date | Insider | Position | Transaction | Shares | Price | Value | Shares Held After | Ownership |
|---|---|---|---|---|---|---|---|---|
| 21 Aug, 2026 | Constantin Ionel Stefan | Chief Technology Officer | Disposed S | 29,681 | $10.34 | $306.93K | 771,629 | Direct |
| 21 Aug, 2026 | Thomas M Stepien | Chief Executive Officer | Disposed S | 23,529 | $10.34 | $243.31K | 602,096 | Direct |
| 21 Aug, 2026 | Kang Sun | Director | Disposed S | 62,101 | $10.34 | $642.19K | 1,218,397 | Direct |
| 24 Aug, 2026 | Thomas M Stepien | Chief Executive Officer | Disposed S | 8,000 | $10.03 | $80.24K | 594,096 | Direct |
| 25 Aug, 2026 | Thomas M Stepien | Chief Executive Officer | Disposed G | 5,000 | $0.00 | $0 | 589,096 | Direct |
| 25 Aug, 2026 | Thomas M Stepien | Chief Executive Officer | Disposed G | 5,000 | $0.00 | $0 | 584,096 | Direct |
| 25 Aug, 2026 | Thomas M Stepien | Chief Executive Officer | Disposed G | 5,000 | $0.00 | $0 | 579,096 | Direct |
| 25 Aug, 2026 | Thomas M Stepien | Chief Executive Officer | Disposed G | 346 | $0.00 | $0 | 578,750 | Direct |
| 25 Aug, 2026 | Thomas M Stepien | Chief Executive Officer | Acquired A | 346 | $0.00 | $0 | 37,260 | Indirect |
| 12 Jun, 2026 | Livingston Satterthwaite | Director | Acquired A | 10,423 | $0.00 | $0 | 346,506 | Direct |
| 12 Jun, 2026 | Donald R Dixon | Director | Acquired A | 10,423 | $0.00 | $0 | 280,079 | Direct |
| 12 Jun, 2026 | Kathleen A Bayless | Director | Acquired A | 10,423 | $0.00 | $0 | 216,120 | Direct |
| 12 Jun, 2026 | Steven Chu | Director | Acquired A | 10,423 | $0.00 | $0 | 137,762 | Direct |
| 15 Jun, 2026 | Donald R Dixon | Director | Disposed S | 85,000 | $17.17 | $1.46Mn | 359,380 | Indirect |
| 09 Jun, 2026 | Donald R Dixon | Director | Disposed S | 40,000 | $19.13 | $765.20K | 444,380 | Indirect |
| 04 Jun, 2026 | Thomas M Stepien | Chief Executive Officer | Disposed G | 30,384 | $0.00 | $0 | 664,539 | Direct |
| 04 Jun, 2026 | Thomas M Stepien | Chief Executive Officer | Disposed G | 36,914 | $0.00 | $0 | 627,625 | Direct |
| 04 Jun, 2026 | Thomas M Stepien | Chief Executive Officer | Acquired G | 36,914 | $0.00 | $0 | 36,914 | Indirect |
| 04 Jun, 2026 | Thomas M Stepien | Chief Executive Officer | Disposed S | 2,000 | $20.97 | $41.94K | 625,625 | Direct |
| 26 May, 2026 | Donald R Dixon | Director | Disposed S | 17,895 | $17.90 | $320.25K | 484,380 | Indirect |