AMPX insider buying and SEC filings, explained
Amprius Technologies, Inc. · CIK 1899287
Tracked: Forms 3/4/5, 8-K, NT · All filings on sec.gov
Company profile
- Exchanges
- NYSE, NYSE
- Industry (SIC)
- Miscellaneous Electrical Machinery, Equipment & Supplies
- State of incorporation
- DE
- Fiscal year end
- Dec 31
- Former names
- Kensington Capital Acquisition Corp. IV
Insider activity in the last 12 months
Bought
$0
Insiders who bought
0
Sold (not marked 10b5-1)
$18.8M
Planned sales (10b5-1)
$64.1M
Insider purchases and sales, last 12 months
| Traded | Type | What was filed | Source |
|---|---|---|---|
| Aug 21–24, 2026 | Sale | Thomas M Stepien (CEO and Director) sold 31,529 shares between Aug 21 and Aug 24 at about $10.26 ($324K). Holdings down 5% to 594,096 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Aug 25, 2026 |
| Aug 21, 2026 | Sale | Constantin Ionel Stefan (Chief Technology Officer) sold 29,681 shares at $10.34 ($307K). Holdings down 4% to 771,629 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Aug 25, 2026 |
| Aug 21, 2026 | Sale | Kang Sun (Director) sold 62,101 shares at $10.34 ($642K). Holdings down 5% to 1,218,397 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Aug 25, 2026 |
| Jun 15, 2026 | Sale | Donald R. Dixon (Director) sold 85,000 shares indirectly at $17.17 ($1.5M). Indirect holdings down 19% to 359,380 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Jun 16, 2026 |
| Jun 9, 2026 | Sale | Donald R. Dixon (Director) sold 40,000 shares indirectly at $19.13 ($765K). Indirect holdings down 8% to 444,380 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Jun 11, 2026 |
| Jun 4, 2026 | Sale | Thomas M Stepien (CEO and Director) sold 2,000 shares at $20.97 ($42K). Holdings down <1% to 625,625 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Jun 5, 2026 |
| May 27, 2026 | Sale | Thomas M Stepien (CEO and Director) sold 4,375 shares at $17.19 ($75K). Holdings down 1% to 694,923 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed May 28, 2026 |
| May 27, 2026 | Sale | Constantin Ionel Stefan (Chief Technology Officer) sold 3,208 shares at $17.19 ($55K). Holdings down <1% to 801,310 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed May 28, 2026 |
| May 27, 2026 | Sale | Kang Sun (Director) sold 356 shares at $17.19 ($6K). Holdings down <1% to 1,280,498 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed May 28, 2026 |
| May 26, 2026 | Sale | Donald R. Dixon (Director) sold 17,895 shares indirectly at $17.90 ($320K). Indirect holdings down 4% to 484,380 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed May 28, 2026 |
| May 21, 2026 | Sale | Thomas M Stepien (CEO and Director) sold 60,702 shares at $14.79 ($898K). Holdings down 8% to 699,298 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed May 26, 2026 |
| May 21, 2026 | Sale | Constantin Ionel Stefan (Chief Technology Officer) sold 28,812 shares at $14.79 ($426K). Holdings down 3% to 804,518 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed May 26, 2026 |
| May 21, 2026 | Sale | Kang Sun (Director) sold 67,796 shares at $14.79 ($1.0M). Holdings down 5% to 1,280,854 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed May 26, 2026 |
| Apr 1, 2026 | Planned (10b5-1) | Kang Sun (Director) sold 1,500,000 shares at about $15.90 ($23.9M), marked as a 10b5-1 plan trade. Holdings down 53% to 1,342,400 shares. | SEC filing Filed Apr 2, 2026 |
| Mar 23, 2026 | Planned (10b5-1) | Kang Sun (Director) sold 217,869 shares indirectly at about $18.80 ($4.1M), marked as a 10b5-1 plan trade. Indirect holdings down 79% to 56,406 shares. | SEC filing Filed Mar 24, 2026 |
| Mar 12, 2026 | Sale | Wen Hsuan HSIEH (Director) sold 413,146 shares at about $18.45 ($7.6M). Holdings down 90% to 44,444 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Mar 13, 2026 |
| Mar 10, 2026 | Sale | Steven Chu (Director) sold 166,632 shares at $17.92 ($3.0M). Holdings down 57% to 127,339 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Mar 12, 2026 |
| Feb 23, 2026 | Sale | Constantin Ionel Stefan (Chief Technology Officer) sold 25,366 shares at $10.16 ($258K). Holdings down 3% to 723,330 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Feb 24, 2026 |
| Feb 23, 2026 | Sale | Kang Sun (Director) sold 61,251 shares at $10.16 ($622K). Holdings down 4% to 1,342,400 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Feb 24, 2026 |
| Jan 28, 2026 | Planned (10b5-1) | Constantin Ionel Stefan (Chief Technology Officer) sold 39,690 shares at $12.00 ($476K), marked as a 10b5-1 plan trade. Holdings down 5% to 748,696 shares. | SEC filing Filed Jan 30, 2026 |
| Jan 21–23, 2026 | Planned (10b5-1) | Constantin Ionel Stefan (Chief Technology Officer) sold 567,707 shares between Jan 21 and Jan 23 at about $12.03 ($6.8M), marked as a 10b5-1 plan trade. Holdings down 43% to 748,696 shares. | SEC filing Filed Jan 23, 2026 |
| Jan 16–20, 2026 | Planned (10b5-1) | Kang Sun (Director) sold 993,733 shares between Jan 16 and Jan 20 at about $11.07 ($11.0M), marked as a 10b5-1 plan trade. Holdings down 41% to 1,403,651 shares. | SEC filing Filed Jan 20, 2026 |
| Jan 12, 2026 | Planned (10b5-1) | Kang Sun (Director) sold 506,267 shares at $10.10 ($5.1M), marked as a 10b5-1 plan trade. Holdings down 27% to 1,403,651 shares. | SEC filing Filed Jan 14, 2026 |
| Dec 11, 2025 | Planned (10b5-1) | Constantin Ionel Stefan (Chief Technology Officer) sold 198,255 shares at $10.51 ($2.1M), marked as a 10b5-1 plan trade. Holdings down 21% to 748,696 shares. | SEC filing Filed Dec 15, 2025 |
| Nov 21, 2025 | Sale | Constantin Ionel Stefan (Chief Technology Officer) sold 25,024 shares at $10.08 ($252K). Holdings down 3% to 821,951 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Nov 25, 2025 |
| Nov 21, 2025 | Sale | Kang Sun (CEO and Director) sold 68,655 shares at $10.08 ($692K). Holdings down 5% to 1,403,651 shares. Not marked as a 10b5-1 plan trade. | SEC filing Filed Nov 25, 2025 |
| Nov 17, 2025 | Planned (10b5-1) | Kang Sun (CEO and Director) sold 1,000,000 shares at $10.60 ($10.6M), marked as a 10b5-1 plan trade. Holdings down 40% to 1,472,306 shares. | SEC filing Filed Nov 19, 2025 |
21 routine transactions (such as grants, option exercises or tax withholding) are not listed.
Cluster buys
No cluster buys in the last 12 months.
Red flags
No red flags in the last 12 months.
Key events
No key events in the last 12 months.
8-K filings, last 12 months
No 8-K filings in the last 12 months.
Red flags are objective triggers only: the item or form filed, never an opinion.
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