Amprius Technologies, Inc. (AMPX) shareholders
AMPXNYSEMiscellaneous Electrical Machinery, Equipment & SuppliesFiscal year ends December 31Also trades as AMPX.WT
Financials through Q3 FY2026, quarter ended Sep 30, 2026Last filing: 10-Q on Nov 12, 2026Score 12/3022% above fair value
$7.93−0.42 (-5.03%)
Close on Nov 13, 2026Market cap $1.16BP/E –Yield –
Ownership
Institutional holdings as of Jun 30, 2026, from 13F filings
Held by institutions
97M
Shares held, 13F filers
Institutional holders
262
64 new, 45 sold out
Net institutional buying
13M
In Q2 2026
Insider trades, 12 months
0 buys · 37 sales
Net sold $85.69M
Shares held by institutions
Holders of more than 5%
Latest Schedule 13D (active) or 13G (passive) filed by each holder
| Holder | Shares | % of class | Filing | As of |
|---|---|---|---|---|
| BlackRock, Inc. | 10,700,817 | 7.40% | 13G (passive) amendment | Jun 30, 2026 |
| Kang Sun | 7,766,174 | 6.80% | 13D (active) | Oct 23, 2024 |
| SAIF IV GP Capital Ltd. Joint filing with SAIF Partners IV L.P. (6.30%), Saif Iv Gp, L.P. (6.30%) and 1 more | 7,608,537 | 6.30% | 13G (passive) amendment | Mar 31, 2025 |
| Donald R. Dixon Joint filing with Trident Capital Management VI, L.L.C. (6.50%), John H. Moragne (6.50%) and 1 more | 7,553,157 | 7.10% | 13D (active) | Oct 23, 2024 |
Top institutional holders
13F holdings as of Jun 30, 2026
| Holder | Shares | % of AMPX | Value | Change | % of portfolio |
|---|---|---|---|---|---|
| BlackRock, Inc. | 11,335,092 | – | $157.10M | +2,109,481 | 0.00% |
| Vanguard Capital Management LLC | 5,562,985 | – | $77.10M | +654,110 | 0.00% |
| Morgan Stanley | 5,105,505 | – | $70.76M | +1,943,338 | 0.00% |
| Two Sigma Investments, LP | 4,318,630 | – | $59.86M | +812,555 | 0.04% |
| UBS Group AG | 4,072,269 | – | $56.44M | +1,760,715 | 0.01% |
| Geode Capital Management, LLC | 3,520,655 | – | $48.81M | +706,125 | 0.00% |
| Jane Street Group, LLC | 3,401,071 | – | $47.14M | −759,585 | 0.00% |
| State Street Corp | 3,240,285 | – | $44.91M | +527,655 | 0.00% |
| Goldman Sachs Group Inc | 2,542,294 | – | $35.24M | +316,113 | 0.00% |
| Jupiter Asset Management Ltd | 2,133,397 | – | $29.57M | New | 0.15% |
| LMR Partners LLP | 1,750,850 | – | $24.27M | New | 0.09% |
| Citadel Advisors LLC | 1,676,344 | – | $23.23M | +237,684 | 0.00% |
| Price T Rowe Associates Inc /Md/ | 1,635,883 | – | $22.68M | −261,537 | 0.00% |
| Vanguard Portfolio Management LLC | 1,457,629 | – | $20.20M | +384,233 | 0.00% |
| Hood River Capital Management LLC | 1,412,516 | – | $19.58M | +463,369 | 0.14% |
| Renaissance Technologies LLC | 1,408,925 | – | $19.53M | +1,049,400 | 0.03% |
| Driehaus Capital Management LLC | 1,345,269 | – | $18.65M | −2,448,909 | 0.11% |
| Baird Financial Group, Inc. | 1,324,909 | – | $18.36M | −260,189 | 0.03% |
| Healthcare Of Ontario Pension Plan Trust Fund | 1,248,700 | – | $17.31M | New | 0.02% |
| Northern Trust Corp | 1,229,628 | – | $17.04M | +207,003 | 0.00% |
Institutional buying and selling by quarter
Positions opened, added to, reduced and closed by 13F filers
| Quarter | Holders | Shares held | New / added | Reduced / closed | Shares bought | Shares sold |
|---|---|---|---|---|---|---|
| Q2 2026 | 262 | 97M | 64 / 111 | 64 / 45 | 30M | 18M |
| Q1 2026 | 245 | 85M | 79 / 94 | 57 / 36 | 38M | 14M |
| Q4 2025 | 206 | 68M | 49 / 86 | 53 / 28 | 17M | 13M |
| Q3 2025 | 187 | 64M | 86 / 63 | 27 / 18 | 35M | 9M |
| Q2 2025 | 121 | 38M | 39 / 46 | 21 / 17 | 19M | 2M |
| Q1 2025 | 100 | 21M | 31 / 34 | 16 / 21 | 7M | 3M |
| Q4 2024 | 91 | 17M | 36 / 29 | 10 / 11 | 11M | 2M |
| Q3 2024 | 66 | 8M | 13 / 27 | 12 / 10 | 3M | 2M |
| Q2 2024 | 65 | 9M | 23 / 22 | 7 / 6 | 5M | 1M |
| Q1 2024 | 50 | 5M | 8 / 16 | 16 / 7 | 1M | 0M |
| Q4 2023 | 49 | 5M | 8 / 22 | 8 / 3 | 1M | 0M |
| Q3 2023 | 46 | 4M | 10 / 16 | 8 / 5 | 2M | 1M |
Top mutual fund and ETF holders
Latest monthly portfolio reports (Form N-PORT)
188 funds held AMPX in Q2 2026, 58% of their shares through ETFs. Each fund counts once per quarter, from its quarter-end report.
| Fund | Shares | % of AMPX | Value | % of fund | As of |
|---|---|---|---|---|---|
| Vanguard Total Stock Market Index Fund | 3,824,005 | – | $53.00M | 0.00% | Jun 30, 2026 |
| iShares Russell 2000 ETF | 3,581,914 | – | $49.65M | 0.06% | Jun 30, 2026 |
| Vanguard Extended Market Index Fund | 1,625,154 | – | $22.52M | 0.02% | Jun 30, 2026 |
| Fidelity Small Cap Index Fund | 1,503,625 | – | $14.43M | 0.04% | Jul 31, 2026 |
| Vanguard Explorer Fund | 1,378,248 | – | $13.23M | 0.06% | Jul 31, 2026 |
| iShares Russell 2000 Growth ETF | 1,257,273 | – | $17.43M | 0.11% | Jun 30, 2026 |
| T. Rowe Price New Horizons Fund, Inc. | 949,401 | – | $13.16M | 0.09% | Jun 30, 2026 |
| Strategas Macro Thematic Opportunities ETF | 888,376 | – | $12.31M | 1.40% | Jun 30, 2026 |
| Fidelity Extended Market Index Fund | 675,351 | – | $13.70M | 0.03% | May 31, 2026 |
| Schwab U.S. Small-Cap ETF | 626,393 | – | $12.70M | 0.06% | May 31, 2026 |
| Oberweis Micro-Cap Fund | 613,700 | – | $8.51M | 0.53% | Jun 30, 2026 |
| Vanguard Russell 2000 Index Fund | 591,688 | – | $12.00M | 0.07% | May 31, 2026 |
| First Trust Small Cap Growth AlphaDEX Fund | 506,522 | – | $4.86M | 0.37% | Jul 31, 2026 |
| MFS New Discovery Fund | 484,851 | – | $9.83M | 0.46% | May 31, 2026 |
| Invesco WilderHill Clean Energy ETF | 479,706 | – | $4.61M | 1.10% | Jul 31, 2026 |
Officers, directors and major owners
People who filed Forms 3, 4 or 5 in the last two years
| Name | Role | Shares owned | Latest filing |
|---|---|---|---|
| Thomas M. Stepien | Chief Executive Officer, Director | 616,010 | Aug 25, 2026 |
| Constantin Ionel Stefan | Chief Technology Officer | 771,629 | Aug 25, 2026 |
| Ricardo C. Rodriguez | Chief Financial Officer | 350,000 | Mar 13, 2026 |
| Sandra Wallach | Chief Financial Officer | 1,005,275 | Aug 25, 2025 |
| Jonathan Bornstein | President of Amprius Lab | 1,485,025 | Mar 12, 2025 |
| Kang Sun | Director | 1,274,803 | Aug 25, 2026 |
| Livingston Satterthwaite | Director | 346,506 | Jun 16, 2026 |
| Donald R. Dixon | Director | 802,601 | Jun 16, 2026 |
| Kathleen A. Bayless | Director | 216,120 | Jun 16, 2026 |
| Steven Chu | Director | 137,762 | Jun 16, 2026 |
| Wen Hsuan HSIEH | Director | 3,993,689 | Mar 13, 2026 |
Insider trades
Common stock transactions reported on Form 4, newest first
| Insider | Date | Transaction | Shares | Price | Value | Shares after |
|---|---|---|---|---|---|---|
| Thomas M. Stepien Chief Executive Officer, Director | Aug 25, 2026 | Award | +346 | – | – | 37,260 |
| Thomas M. Stepien Chief Executive Officer, Director | Aug 25, 2026 | Gift | −346 | – | – | 578,750 |
| Thomas M. Stepien Chief Executive Officer, Director | Aug 25, 2026 | Gift | −5,000 | – | – | 579,096 |
| Thomas M. Stepien Chief Executive Officer, Director | Aug 25, 2026 | Gift | −5,000 | – | – | 584,096 |
| Thomas M. Stepien Chief Executive Officer, Director | Aug 25, 2026 | Gift | −5,000 | – | – | 589,096 |
| Thomas M. Stepien Chief Executive Officer, Director | Aug 24, 2026 | Sale | −8,000 | $10.03 | $80.24K | 594,096 |
| Kang Sun Director | Aug 21, 2026 | Sale | −62,101 | $10.34 | $642.12K | 1,218,397 |
| Constantin Ionel Stefan Chief Technology Officer | Aug 21, 2026 | Sale | −29,681 | $10.34 | $306.90K | 771,629 |
| Thomas M. Stepien Chief Executive Officer, Director | Aug 21, 2026 | Sale | −23,529 | $10.34 | $243.29K | 602,096 |
| Donald R. Dixon Director | Jun 15, 2026 | Sale | −85,000 | $17.17 | $1.46M | 359,380 |
| Steven Chu Director | Jun 12, 2026 | Award | +10,423 | – | – | 137,762 |
| Livingston Satterthwaite Director | Jun 12, 2026 | Award | +10,423 | – | – | 346,506 |
| Donald R. Dixon Director | Jun 12, 2026 | Award | +10,423 | – | – | 280,079 |
| Kathleen A. Bayless Director | Jun 12, 2026 | Award | +10,423 | – | – | 216,120 |
| Donald R. Dixon Director | Jun 9, 2026 | Sale | −40,000 | $19.13 | $765.20K | 444,380 |
| Thomas M. Stepien Chief Executive Officer, Director | Jun 4, 2026 | Gift | −36,914 | – | – | 627,625 |
| Thomas M. Stepien Chief Executive Officer, Director | Jun 4, 2026 | Gift | −30,384 | – | – | 664,539 |
| Thomas M. Stepien Chief Executive Officer, Director | Jun 4, 2026 | Sale | −2,000 | $20.97 | $41.94K | 625,625 |
| Thomas M. Stepien Chief Executive Officer, Director | Jun 4, 2026 | Gift | +36,914 | – | – | 36,914 |
| Thomas M. Stepien Chief Executive Officer, Director | May 27, 2026 | Sale | −4,375 | $17.19 | $75.21K | 694,923 |
| Constantin Ionel Stefan Chief Technology Officer | May 27, 2026 | Sale | −3,208 | $17.19 | $55.15K | 801,310 |
| Kang Sun Director | May 27, 2026 | Sale | −356 | $17.19 | $6.12K | 1,280,498 |
| Donald R. Dixon Director | May 26, 2026 | Sale | −17,895 | $17.90 | $320.32K | 484,380 |
| Kang Sun Director | May 21, 2026 | Sale | −67,796 | $14.79 | $1.00M | 1,280,854 |
| Constantin Ionel Stefan Chief Technology Officer | May 21, 2026 | Sale | −28,812 | $14.79 | $426.13K | 804,518 |
| Thomas M. Stepien Chief Executive Officer, Director | May 21, 2026 | Sale | −60,702 | $14.79 | $897.78K | 699,298 |
| Kang Sun Director | May 5, 2026 | Award | +6,250 | – | – | 1,348,650 |
| Kang Sun Director | Apr 1, 2026 | Sale(10b5-1 plan) | −249,037 | $16.78 | $4.18M | 1,342,400 |
| Kang Sun Director | Apr 1, 2026 | Option exercise | +1,312,505 | $1.78 | $2.34M | 2,654,905 |
| Kang Sun Director | Apr 1, 2026 | Option exercise | +187,495 | $3.68 | $689.98K | 2,842,400 |
| Kang Sun Director | Apr 1, 2026 | Sale(10b5-1 plan) | −1,250,963 | $15.73 | $19.68M | 1,591,437 |
| Kang Sun Director | Mar 23, 2026 | Sale(10b5-1 plan) | −152,823 | $18.69 | $2.86M | 121,452 |
| Kang Sun Director | Mar 23, 2026 | Sale(10b5-1 plan) | −65,046 | $19.06 | $1.24M | 56,406 |
| Wen Hsuan HSIEH Director | Mar 12, 2026 | Sale | −130,646 | $18.22 | $2.38M | 44,444 |
| Wen Hsuan HSIEH Director | Mar 12, 2026 | Sale | −282,500 | $18.55 | $5.24M | 175,090 |
| Wen Hsuan HSIEH Director | Mar 12, 2026 | Option exercise | +270,251 | $2.61 | $705.36K | 457,590 |
| Steven Chu Director | Mar 12, 2026 | Sale | −5,565 | $18.53 | $103.12K | 127,339 |
| Steven Chu Director | Mar 12, 2026 | Option exercise | +69,422 | $0.62 | $43.04K | 282,904 |
| Steven Chu Director | Mar 12, 2026 | Option exercise | +86,143 | $2.61 | $224.83K | 213,482 |
| Steven Chu Director | Mar 12, 2026 | Sale | −100,000 | $18.65 | $1.86M | 182,904 |
| Steven Chu Director | Mar 12, 2026 | Sale | −50,000 | $18.21 | $910.50K | 132,904 |
| Steven Chu Director | Mar 10, 2026 | Sale | −166,632 | $17.92 | $2.99M | 127,339 |
| Steven Chu Director | Mar 10, 2026 | Option exercise | +104,132 | $0.62 | $64.56K | 293,971 |
| Ricardo C. Rodriguez Chief Financial Officer | Mar 4, 2026 | Award | +150,000 | – | – | 350,000 |
| Constantin Ionel Stefan Chief Technology Officer | Mar 4, 2026 | Award | +110,000 | – | – | 833,330 |
| Thomas M. Stepien Chief Executive Officer, Director | Mar 4, 2026 | Award | +150,000 | – | – | 760,000 |
| Ricardo C. Rodriguez Chief Financial Officer | Mar 4, 2026 | Award | +150,000 | – | – | 350,000 |
| Constantin Ionel Stefan Chief Technology Officer | Feb 23, 2026 | Sale | −25,366 | $10.16 | $257.72K | 723,330 |
| Kang Sun Director | Feb 23, 2026 | Sale | −61,251 | $10.16 | $622.31K | 1,342,400 |
| Constantin Ionel Stefan Chief Technology Officer | Jan 28, 2026 | Sale(10b5-1 plan) | −39,690 | $12.00 | $476.28K | 748,696 |
| Constantin Ionel Stefan Chief Technology Officer | Jan 28, 2026 | Option exercise | +90 | $0.62 | $56 | 748,786 |
| Constantin Ionel Stefan Chief Technology Officer | Jan 28, 2026 | Option exercise | +39,600 | $0.05 | $1.98K | 788,386 |
| Constantin Ionel Stefan Chief Technology Officer | Jan 23, 2026 | Sale(10b5-1 plan) | −1,600 | $12.00 | $19.20K | 748,696 |
| Constantin Ionel Stefan Chief Technology Officer | Jan 23, 2026 | Option exercise | +1,600 | $0.05 | $80 | 750,296 |
| Constantin Ionel Stefan Chief Technology Officer | Jan 22, 2026 | Option exercise | +253,928 | $0.05 | $12.70K | 1,002,624 |
| Constantin Ionel Stefan Chief Technology Officer | Jan 22, 2026 | Option exercise | +72,795 | $0.45 | $32.76K | 1,075,419 |
| Constantin Ionel Stefan Chief Technology Officer | Jan 22, 2026 | Option exercise | +166,104 | $0.05 | $8.31K | 1,241,523 |
| Constantin Ionel Stefan Chief Technology Officer | Jan 22, 2026 | Sale(10b5-1 plan) | −492,827 | $12.04 | $5.93M | 748,696 |
| Constantin Ionel Stefan Chief Technology Officer | Jan 21, 2026 | Option exercise | +15,883 | $0.05 | $794 | 821,976 |
| Constantin Ionel Stefan Chief Technology Officer | Jan 21, 2026 | Sale(10b5-1 plan) | −73,280 | $12.00 | $879.36K | 748,696 |
Awards, option exercises, tax withholding and gifts are shown alongside open-market buys and sales. Each name links to the filing on SEC EDGAR.
Short interest
Shares sold short and not yet bought back, as of Oct 30, 2026 (FINRA, reported twice a month)
Short % of float
16.14%
22M shares short
Days to cover
4.3
At 5M shares a day
Change since last report
-4.1%
From 23M shares
Short volume, 20 days
50.2%
Of volume reported to FINRA
Shares sold short, last 12 months
Short sale volume counts trades marked short on any given day, including market-maker hedging, so it runs far higher than the share of Amprius Technologies's stock actually held short. Settlement fails (shares not delivered on time) peaked at 95,520 shares on Oct 8, 2026 over the last 90 days.
Planned insider sales
Notices of proposed sale filed on Form 144 before shares are sold
| Seller | Filed | Shares | Market value | Planned sale | Acquired through |
|---|---|---|---|---|---|
| Kang Sun Director | Aug 25, 2026 | 62,101 | $642.18K | Aug 21, 2026 | Release of restricted stock units |
| Thomas M. Stepien OFFICER, DIRECTOR | Aug 25, 2026 | 23,529 | $243.31K | Aug 21, 2026 | Release of restricted stock units |
| Constantin Ionel Stefan OFFICER | Aug 25, 2026 | 29,681 | $306.93K | Aug 21, 2026 | Release of restricted stock units |
| Thomas M. Stepien Officer, Director | Aug 24, 2026 | 8,000 | $80.24K | Aug 24, 2026 | Restricted Stock Vesting Under a Registered Plan |
| Donald R. Dixon Director | Jun 8, 2026 | 125,000 | $2.36M | Jun 8, 2026 | Restricted Stock Unit |
| Thomas M. Stepien Officer, Director | Jun 4, 2026 | 2,000 | $41.94K | Jun 4, 2026 | Restricted Stock Vesting Under a Registered Plan |
| Constantin Ionel Stefan Officer | May 28, 2026 | 3,208 | $55.16K | May 27, 2026 | Release of restricted stock units |
| Thomas M. Stepien Officer, Director | May 28, 2026 | 4,375 | $75.22K | May 27, 2026 | Release of restricted stock units |
| Kang Sun Director | May 28, 2026 | 356 | $6.12K | May 27, 2026 | Release of restricted stock units |
| Donald R. Dixon Director | May 26, 2026 | 17,895 | $315.85K | May 26, 2026 | Restricted Stock Unit |
| Thomas M. Stepien Officer, Director | May 26, 2026 | 60,702 | $897.69K | May 21, 2026 | Release of restricted stock units |
| Constantin Ionel Stefan Officer | May 26, 2026 | 28,812 | $426.08K | May 21, 2026 | Release of restricted stock units |
| Kang Sun Director | May 26, 2026 | 67,796 | $1.00M | May 21, 2026 | Release of restricted stock units |
| Kang Sun Director, Officer | Apr 1, 2026 | 1,500,000 | $25.29M | Apr 1, 2026 | Exercise of Stock Options |
| Kang Sun Director | Mar 23, 2026 | 192,727 | $3.51M | Mar 23, 2026 | Restricted Stock Units |
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