Amprius Technologies (AMPX)
Amprius Technologies on one page: short interest, daily short volume, fails to deliver, planned sales, large holders, 13F holders, earnings dates and insider trades. Listed on NYSE, classified by the SEC as miscellaneous electrical machinery, equipment & supplies.
22.7M
Short interest
settlement 2026-10-15
3.8
Days to cover
unchanged vs prior
54.1%
Short share of volume
2026-11-02
70
Fails to deliver
settlement 2026-10-13
Thu 5 Nov
Next earnings
estimated date
-$1.3M
Insider flow, 90 days
0 buys, 4 sells
As of 2026-11-02.
Short interest
FINRA, twice a month. The newest 48 settlements in the table, 48 in the chart. JSONAs of 15 October 2026, short interest in AMPX is 22,724,816 shares, up 39,338 shares over the last month. Over the last 48 readings it ranged from 2,789,228 shares (15 January 2025) to 28,034,609 shares (15 July 2026). At the reported average volume of 6.0M shares a day that is 3.8 days to cover.
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| Settlement | Shares short | Change | Avg daily volume | Days to cover |
|---|---|---|---|---|
| 2026-10-15 | 22,724,816 | -0.4% | 5,961,116 | 3.81 |
| 2026-09-30 | 22,815,859 | +0.6% | 6,005,257 | 3.80 |
| 2026-09-15 | 22,685,478 | -2.0% | 4,464,521 | 5.08 |
| 2026-08-31 | 23,159,125 | +4.6% | 4,385,259 | 5.28 |
| 2026-08-14 | 22,146,891 | -7.4% | 7,163,836 | 3.09 |
| 2026-07-31 | 23,928,102 | -14.7% | 5,752,370 | 4.16 |
| 2026-07-15 | 28,034,609 | +6.6% | 6,644,710 | 4.22 |
| 2026-06-30 | 26,309,329 | +15.3% | 8,191,705 | 3.21 |
| 2026-06-15 | 22,816,138 | -11.0% | 7,285,767 | 3.13 |
| 2026-05-29 | 25,637,309 | +13.0% | 10,894,061 | 2.35 |
| 2026-05-15 | 22,692,523 | -2.3% | 10,110,297 | 2.24 |
| 2026-04-30 | 23,225,858 | +7.8% | 8,535,425 | 2.72 |
| 2026-04-15 | 21,551,498 | +20.3% | 7,288,161 | 2.96 |
| 2026-03-31 | 17,909,138 | +0.3% | 7,882,322 | 2.27 |
| 2026-03-13 | 17,846,503 | -6.8% | 13,965,363 | 1.28 |
| 2026-02-27 | 19,141,715 | +12.3% | 5,976,839 | 3.20 |
| 2026-02-13 | 17,042,918 | -3.3% | 9,160,955 | 1.86 |
| 2026-01-30 | 17,620,761 | +2.2% | 9,869,914 | 1.79 |
| 2026-01-15 | 17,246,418 | +5.9% | 6,964,389 | 2.48 |
| 2025-12-31 | 16,283,031 | +22.5% | 5,914,386 | 2.75 |
| 2025-12-15 | 13,292,515 | -1.6% | 4,980,428 | 2.67 |
| 2025-11-28 | 13,514,161 | -15.9% | 5,902,338 | 2.29 |
| 2025-11-14 | 16,066,241 | +4.6% | 9,691,339 | 1.66 |
| 2025-10-31 | 15,356,669 | -8.9% | 8,332,213 | 1.84 |
| 2025-10-15 | 16,851,368 | -6.5% | 10,978,414 | 1.53 |
| 2025-09-30 | 18,024,182 | +32.0% | 10,513,255 | 1.71 |
| 2025-09-15 | 13,651,786 | +19.1% | 7,401,104 | 1.84 |
| 2025-08-29 | 11,457,481 | +13.7% | 5,052,274 | 2.27 |
| 2025-08-15 | 10,074,212 | +9.2% | 9,744,163 | 1.03 |
| 2025-07-31 | 9,224,900 | +27.1% | 10,147,045 | 1.00 |
| 2025-07-15 | 7,255,148 | +53.2% | 11,188,735 | 1.00 |
| 2025-06-30 | 4,736,413 | -11.9% | 6,135,521 | 1.00 |
| 2025-06-13 | 5,378,549 | -8.2% | 4,537,656 | 1.19 |
| 2025-05-30 | 5,856,822 | +10.5% | 3,540,534 | 1.65 |
| 2025-05-15 | 5,300,949 | -4.6% | 3,012,655 | 1.76 |
| 2025-04-30 | 5,557,859 | -1.3% | 2,710,866 | 2.05 |
| 2025-04-15 | 5,628,147 | -18.7% | 2,513,341 | 2.24 |
| 2025-03-31 | 6,921,326 | +84.5% | 5,613,837 | 1.23 |
| 2025-03-14 | 3,752,456 | -9.1% | 2,484,021 | 1.51 |
| 2025-02-28 | 4,126,988 | -7.9% | 2,772,245 | 1.49 |
| 2025-02-14 | 4,482,929 | +12.7% | 2,741,986 | 1.63 |
| 2025-01-31 | 3,977,654 | +42.6% | 3,692,710 | 1.08 |
| 2025-01-15 | 2,789,228 | -4.3% | 5,118,896 | 1.00 |
| 2024-12-31 | 2,916,189 | -20.4% | 4,973,082 | 1.00 |
| 2024-12-13 | 3,663,338 | +5.9% | 3,501,999 | 1.05 |
| 2024-11-29 | 3,460,122 | +3.7% | 1,954,996 | 1.77 |
| 2024-11-15 | 3,337,874 | -30.5% | 3,502,498 | 1.00 |
| 2024-10-31 | 4,799,734 | +42.1% | 2,097,802 | 2.29 |
Daily short volume
FINRA Reg SHO, the last 30 sessions. JSONAs of 2 November 2026, the short share of AMPX volume is 54.1%, down 16.8 points over the last five sessions. Over the last 30 readings it ranged from 33.2% (6 October 2026) to 71.0% (26 October 2026). The latest reading is 6.6 points above the 30-session average of 47.6%, on 1.8M shares reported.
| Date | Short volume | Total volume | Short share | Exempt |
|---|---|---|---|---|
| 2026-11-02 | 950K | 1.8M | 54.1% | 10 |
| 2026-10-30 | 1.2M | 2.2M | 55.9% | 4,024 |
| 2026-10-29 | 640K | 1.4M | 44.4% | 333 |
| 2026-10-28 | 622K | 1.5M | 41.3% | 0 |
| 2026-10-27 | 799K | 2.1M | 38.8% | 13,792 |
| 2026-10-26 | 1.2M | 1.7M | 71.0% | 16,671 |
| 2026-10-23 | 1.3M | 2.1M | 63.5% | 2,000 |
| 2026-10-22 | 1.2M | 2.0M | 58.6% | 143 |
| 2026-10-21 | 1.4M | 2.8M | 50.3% | 2,011 |
| 2026-10-20 | 717K | 1.6M | 43.9% | 1,975 |
| 2026-10-19 | 758K | 1.5M | 50.3% | 0 |
| 2026-10-16 | 1.0M | 2.0M | 51.1% | 5,200 |
| 2026-10-15 | 2.1M | 4.0M | 53.3% | 25,353 |
| 2026-10-14 | 1.2M | 2.9M | 40.7% | 6,993 |
| 2026-10-13 | 986K | 2.2M | 45.2% | 6,244 |
| 2026-10-12 | 677K | 1.6M | 41.4% | 3,648 |
| 2026-10-09 | 996K | 2.4M | 42.0% | 1,300 |
| 2026-10-08 | 595K | 1.8M | 33.6% | 600 |
| 2026-10-07 | 1.3M | 2.6M | 48.7% | 2,269 |
| 2026-10-06 | 536K | 1.6M | 33.2% | 1,851 |
| 2026-10-05 | 1.2M | 2.4M | 50.1% | 1,743 |
| 2026-10-02 | 724K | 1.8M | 39.5% | 0 |
| 2026-10-01 | 722K | 1.7M | 42.8% | 0 |
| 2026-09-30 | 1.1M | 2.7M | 42.1% | 6,620 |
| 2026-09-29 | 1.3M | 2.9M | 46.8% | 6,885 |
| 2026-09-28 | 3.2M | 6.5M | 48.4% | 60,549 |
| 2026-09-25 | 750K | 1.5M | 49.0% | 21,260 |
| 2026-09-24 | 839K | 1.7M | 49.1% | 12,426 |
| 2026-09-23 | 1.4M | 2.5M | 54.2% | 7,978 |
| 2026-09-22 | 695K | 1.6M | 43.5% | 16,330 |
Fails to deliver
SEC, the last 30 settlement dates with a fail. JSONAs of 13 October 2026, the fails-to-deliver balance in AMPX is 70 shares, down 95,450 shares over the last settlement date. Over the last 30 readings it ranged from 19 shares (23 September 2026) to 95,520 shares (8 October 2026). The latest reading sits at the bottom of that range.
| Settlement | Shares failed | Price | Value |
|---|---|---|---|
| 2026-10-13 | 70 | $8.87 | $621 |
| 2026-10-08 | 95,520 | $9.33 | $891K |
| 2026-10-02 | 17,124 | $9.61 | $165K |
| 2026-09-28 | 12,819 | $9.75 | $125K |
| 2026-09-24 | 1,058 | $9.73 | $10K |
| 2026-09-23 | 19 | $9.98 | $190 |
| 2026-09-18 | 36 | $9.54 | $343 |
| 2026-09-11 | 2,421 | $9.55 | $23K |
| 2026-09-02 | 2,846 | $9.48 | $27K |
| 2026-09-01 | 661 | $9.88 | $7K |
| 2026-08-28 | 3,832 | $10.51 | $40K |
| 2026-08-26 | 4,703 | $10.18 | $48K |
| 2026-08-24 | 1,960 | $10.34 | $20K |
| 2026-08-20 | 3,027 | $10.63 | $32K |
| 2026-08-11 | 1,927 | $11.81 | $23K |
| 2026-08-05 | 180 | $10.81 | $2K |
| 2026-07-27 | 30,885 | $9.24 | $285K |
| 2026-07-24 | 1,521 | $9.91 | $15K |
| 2026-07-17 | 591 | $10.10 | $6K |
| 2026-06-30 | 2,370 | $13.52 | $32K |
| 2026-06-26 | 22 | $12.56 | $276 |
| 2026-06-18 | 61 | $15.00 | $915 |
| 2026-06-15 | 2,172 | $16.31 | $35K |
| 2026-06-08 | 5,971 | $19.69 | $118K |
| 2026-06-05 | 1,135 | $22.54 | $26K |
| 2026-06-03 | 106 | $22.91 | $2K |
| 2026-06-02 | 1,478 | $21.75 | $32K |
| 2026-06-01 | 1,411 | $20.28 | $29K |
| 2026-05-29 | 30,069 | $20.85 | $627K |
| 2026-05-27 | 9,964 | $17.83 | $178K |
Insider trades
SEC Form 4, newest first. JSONInsiders at AMPX reported 4 open-market sells worth $1.3M in the last 90 days and no open-market buys. Latest filing: Stepien Thomas M (Chief Executive Officer) on 2026-08-25.
| Date | Insider | Title | Type | Shares | Price | Value | Owned after |
|---|---|---|---|---|---|---|---|
| 2026-08-25 | Stepien Thomas M | Chief Executive Officer | Gift | 5K | $0.00 | $0 | 579K |
| 2026-08-25 | Stepien Thomas M | Chief Executive Officer | Gift | 5K | $0.00 | $0 | 584K |
| 2026-08-25 | Stepien Thomas M | Chief Executive Officer | Grant | 346 | $0.00 | $0 | 37K |
| 2026-08-25 | Stepien Thomas M | Chief Executive Officer | Gift | 346 | $0.00 | $0 | 579K |
| 2026-08-25 | Stepien Thomas M | Chief Executive Officer | Gift | 5K | $0.00 | $0 | 589K |
| 2026-08-24 | Stepien Thomas M | Chief Executive Officer | Sell | 8K | $10.03 | $80K | 594K |
| 2026-08-21 | Stepien Thomas M | Chief Executive Officer | Sell | 24K | $10.34 | $243K | 602K |
| 2026-08-21 | Stefan Constantin Ionel | Chief Technology Officer | Sell | 30K | $10.34 | $307K | 772K |
| 2026-08-21 | Sun Kang | Director | Sell | 62K | $10.34 | $642K | 1.2M |
| 2026-06-15 | DIXON DONALD R | Director | Sell | 85K | $17.17 | $1.5M | 359K |
| 2026-06-12 | SATTERTHWAITE LIVINGSTON | Director | Grant | 10K | $0.00 | $0 | 347K |
| 2026-06-12 | Chu Steven | Director | Grant | 10K | $0.00 | $0 | 138K |
| 2026-06-12 | BAYLESS KATHLEEN A | Director | Grant | 10K | $0.00 | $0 | 216K |
| 2026-06-12 | DIXON DONALD R | Director | Grant | 10K | $0.00 | $0 | 280K |
| 2026-06-09 | DIXON DONALD R | Director | Sell | 40K | $19.13 | $765K | 444K |
| 2026-06-04 | Stepien Thomas M | Chief Executive Officer | Gift | 37K | $0.00 | $0 | 37K |
| 2026-06-04 | Stepien Thomas M | Chief Executive Officer | Sell | 2K | $20.97 | $42K | 626K |
| 2026-06-04 | Stepien Thomas M | Chief Executive Officer | Gift | 37K | $0.00 | $0 | 628K |
| 2026-06-04 | Stepien Thomas M | Chief Executive Officer | Gift | 30K | $0.00 | $0 | 665K |
| 2026-05-27 | Stepien Thomas M | Chief Executive Officer | Sell | 4K | $17.19 | $75K | 695K |
| 2026-05-27 | Stefan Constantin Ionel | Chief Technology Officer | Sell | 3K | $17.19 | $55K | 801K |
| 2026-05-27 | Sun Kang | Director | Sell | 356 | $17.19 | $6K | 1.3M |
| 2026-05-26 | DIXON DONALD R | Director | Sell | 18K | $17.90 | $320K | 484K |
| 2026-05-21 | Stepien Thomas M | Chief Executive Officer | Sell | 61K | $14.79 | $898K | 699K |
| 2026-05-21 | Stefan Constantin Ionel | Chief Technology Officer | Sell | 29K | $14.79 | $426K | 805K |
| 2026-05-21 | Sun Kang | Director | Sell | 68K | $14.79 | $1.0M | 1.3M |
| 2026-05-05 | Sun Kang | Director | Grant | 6K | $0.00 | $0 | 1.3M |
| 2026-04-01 | Sun Kang | Director | Sell | 249K | $16.78 | $4.2M | 1.3M |
| 2026-04-01 | Sun Kang | Director | Sell | 1.3M | $15.73 | $19.7M | 1.6M |
| 2026-04-01 | Sun Kang | Director | Exercise or conversion | 187K | $3.68 | $690K | 2.8M |
| 2026-04-01 | Sun Kang | Director | Exercise or conversion | 1.3M | $1.78 | $2.3M | 2.7M |
| 2026-03-23 | Sun Kang | Director | Sell | 65K | $19.06 | $1.2M | 56K |
| 2026-03-23 | Sun Kang | Director | Sell | 153K | $18.69 | $2.9M | 121K |
| 2026-03-12 | Chu Steven | Director | Sell | 6K | $18.53 | $103K | 127K |
| 2026-03-12 | Chu Steven | Director | Sell | 50K | $18.21 | $911K | 133K |
| 2026-03-12 | Chu Steven | Director | Sell | 100K | $18.65 | $1.9M | 183K |
| 2026-03-12 | Chu Steven | Director | Exercise or conversion | 69K | $0.62 | $43K | 283K |
| 2026-03-12 | Chu Steven | Director | Exercise or conversion | 86K | $2.61 | $225K | 213K |
| 2026-03-12 | HSIEH Wen Hsuan | Director | Sell | 131K | $18.22 | $2.4M | 44K |
| 2026-03-12 | HSIEH Wen Hsuan | Director | Sell | 283K | $18.55 | $5.2M | 175K |
| 2026-03-12 | HSIEH Wen Hsuan | Director | Exercise or conversion | 270K | $2.61 | $705K | 458K |
| 2026-03-10 | Chu Steven | Director | Sell | 167K | $17.92 | $3.0M | 127K |
| 2026-03-10 | Chu Steven | Director | Exercise or conversion | 104K | $0.62 | $65K | 294K |
| 2026-03-04 | Stepien Thomas M | Chief Executive Officer | Grant | 150K | $0.00 | $0 | 760K |
| 2026-03-04 | Stefan Constantin Ionel | Chief Technology Officer | Grant | 110K | $0.00 | $0 | 833K |
| 2026-03-04 | RODRIGUEZ RICARDO C. | Chief Financial Officer | Grant | 150K | $0.00 | $0 | 350K |
| 2026-02-23 | Stefan Constantin Ionel | Chief Technology Officer | Sell | 25K | $10.16 | $258K | 723K |
| 2026-02-23 | Sun Kang | Director | Sell | 61K | $10.16 | $622K | 1.3M |
| 2026-01-28 | Stefan Constantin Ionel | Chief Technology Officer | Sell | 40K | $12.00 | $476K | 749K |
| 2026-01-28 | Stefan Constantin Ionel | Chief Technology Officer | Exercise or conversion | 40K | $0.05 | $2K | 788K |
| 2026-01-28 | Stefan Constantin Ionel | Chief Technology Officer | Exercise or conversion | 90 | $0.62 | $56 | 749K |
| 2026-01-23 | Stefan Constantin Ionel | Chief Technology Officer | Sell | 2K | $12.00 | $19K | 749K |
| 2026-01-23 | Stefan Constantin Ionel | Chief Technology Officer | Exercise or conversion | 2K | $0.05 | $80 | 750K |
| 2026-01-22 | Stefan Constantin Ionel | Chief Technology Officer | Sell | 493K | $12.04 | $5.9M | 749K |
| 2026-01-22 | Stefan Constantin Ionel | Chief Technology Officer | Exercise or conversion | 166K | $0.05 | $8K | 1.2M |
| 2026-01-22 | Stefan Constantin Ionel | Chief Technology Officer | Exercise or conversion | 73K | $0.45 | $33K | 1.1M |
| 2026-01-22 | Stefan Constantin Ionel | Chief Technology Officer | Exercise or conversion | 254K | $0.05 | $13K | 1.0M |
| 2026-01-21 | Stefan Constantin Ionel | Chief Technology Officer | Sell | 73K | $12.00 | $879K | 749K |
| 2026-01-21 | Stefan Constantin Ionel | Chief Technology Officer | Exercise or conversion | 16K | $0.05 | $794 | 822K |
| 2026-01-21 | Stefan Constantin Ionel | Chief Technology Officer | Exercise or conversion | 16K | $0.05 | $792 | 806K |
| 2026-01-21 | Stefan Constantin Ionel | Chief Technology Officer | Exercise or conversion | 42K | $0.62 | $26K | 790K |
| 2026-01-20 | Sun Kang | Director | Sell | 43K | $11.03 | $476K | 1.4M |
| 2026-01-20 | Sun Kang | Director | Exercise or conversion | 43K | $1.78 | $77K | 1.4M |
| 2026-01-16 | Sun Kang | Director | Sell | 951K | $11.07 | $10.5M | 1.4M |
| 2026-01-16 | Sun Kang | Director | Exercise or conversion | 100K | $1.78 | $178K | 2.4M |
| 2026-01-16 | Sun Kang | Director | Exercise or conversion | 850K | $2.50 | $2.1M | 2.3M |
| 2026-01-12 | Sun Kang | Director | Sell | 506K | $10.10 | $5.1M | 1.4M |
| 2026-01-12 | Sun Kang | Director | Exercise or conversion | 117K | $2.50 | $293K | 1.9M |
| 2026-01-12 | Sun Kang | Director | Exercise or conversion | 208K | $2.44 | $508K | 1.8M |
| 2026-01-12 | Sun Kang | Director | Exercise or conversion | 181K | $0.62 | $112K | 1.6M |
| 2025-12-19 | Stepien Thomas M | Chief Executive Officer | Grant | 200K | $0.00 | $0 | 760K |
| 2025-12-19 | Stepien Thomas M | President | Grant | 200K | $0.00 | $0 | 610K |
| 2025-12-11 | Stefan Constantin Ionel | Chief Technology Officer | Sell | 198K | $10.51 | $2.1M | 749K |
| 2025-12-11 | Stefan Constantin Ionel | Chief Technology Officer | Exercise or conversion | 125K | $0.05 | $6K | 947K |
| 2025-11-21 | Stefan Constantin Ionel | Chief Technology Officer | Sell | 25K | $10.08 | $252K | 822K |
| 2025-11-21 | Sun Kang | Chief Executive Officer | Sell | 69K | $10.08 | $692K | 1.4M |
| 2025-11-17 | Sun Kang | Chief Executive Officer | Sell | 1.0M | $10.60 | $10.6M | 1.5M |
| 2025-11-17 | Sun Kang | Chief Executive Officer | Exercise or conversion | 42K | $0.62 | $26K | 2.5M |
| 2025-11-17 | Sun Kang | Chief Executive Officer | Exercise or conversion | 27K | $0.62 | $17K | 2.4M |
| 2025-11-17 | Sun Kang | Chief Executive Officer | Exercise or conversion | 728K | $0.05 | $36K | 2.4M |
| 2025-11-17 | Sun Kang | Chief Executive Officer | Exercise or conversion | 203K | $0.98 | $199K | 1.7M |
| 2025-10-06 | RODRIGUEZ RICARDO C. | Chief Financial Officer | Grant | 200K | $0.00 | $0 | 200K |
| 2025-08-21 | Stefan Constantin Ionel | Chief Technology Officer | Sell | 19K | $6.82 | $131K | 847K |
| 2025-08-21 | Wallach Sandra | Chief Financial Officer | Sell | 28K | $6.82 | $194K | 1.0M |
| 2025-08-21 | Sun Kang | Chief Executive Officer | Sell | 66K | $6.82 | $448K | 1.5M |
| 2025-06-13 | HSIEH Wen Hsuan | Director | Grant | 44K | $0.00 | $0 | 187K |
| 2025-06-13 | DIXON DONALD R | Director | Grant | 44K | $0.00 | $0 | 395K |
| 2025-06-13 | SATTERTHWAITE LIVINGSTON | Director | Grant | 44K | $0.00 | $0 | 336K |
| 2025-06-13 | BAYLESS KATHLEEN A | Director | Grant | 44K | $0.00 | $0 | 206K |
| 2025-06-13 | Chu Steven | Director | Grant | 44K | $0.00 | $0 | 190K |
| 2025-05-21 | Sun Kang | Chief Executive Officer | Sell | 70K | $2.43 | $170K | 1.8M |
| 2025-05-21 | Wallach Sandra | Chief Financial Officer | Sell | 28K | $2.43 | $67K | 1.0M |
| 2025-05-21 | Stefan Constantin Ionel | Chief Technology Officer | Sell | 20K | $2.43 | $49K | 866K |
| 2025-05-01 | Stepien Thomas M | President | Grant | 400K | $0.00 | $0 | 400K |
| 2025-03-19 | Stefan Constantin Ionel | Chief Technology Officer | Grant | 462K | $0.00 | $0 | 887K |
| 2025-03-19 | Wallach Sandra | Chief Financial Officer | Grant | 383K | $0.00 | $0 | 1.1M |
| 2025-03-19 | Sun Kang | Chief Executive Officer | Grant | 599K | $0.00 | $0 | 1.9M |
| 2025-03-14 | Stefan Constantin Ionel | Chief Technology Officer | Exercise or conversion | 3K | $0.98 | $3K | 425K |
| 2025-03-10 | Bornstein Jonathan | President of Amprius Lab | Exercise or conversion | 3K | $0.98 | $3K | 423K |
| 2025-02-21 | Bornstein Jonathan | President of Amprius Lab | Sell | 14K | $3.13 | $42K | 419K |
Form 4 filings are due within two business days of the trade. Insiders sell for many reasons that say nothing about the company; open-market buys are rarer.
Planned sales (Form 144)
Newest first. JSON18 Form 144 notices on file for AMPX worth $83.5M at the prices reported; 1 in the last 90 days worth $80K. Latest: THOMAS M STEPIEN filed on 2026-08-24 to sell 8,000 shares ($80K) from 2026-08-24.
| Filed | Seller | Shares | Market value | Of outstanding | Sale from | Broker |
|---|---|---|---|---|---|---|
| 2026-08-24 | THOMAS M STEPIENOfficer, Director | 8K | $80K | 0.005% | 2026-08-24 | Morgan Stanley Smith Barney LLC Executive Financial Services |
| 2026-06-08 | DIXON DONALD RDirector | 125K | $2.4M | 0.088% | 2026-06-08 | The Charles Schwab Corporation |
| 2026-06-04 | THOMAS M STEPIENOfficer, Director | 2K | $42K | 0.001% | 2026-06-04 | Morgan Stanley Smith Barney LLC Executive Financial Services |
| 2026-05-26 | DIXON DONALD RDirector | 18K | $316K | 0.013% | 2026-05-26 | The Charles Schwab Corporation |
| 2026-04-01 | KANG SUNDirector, Officer | 1.5M | $25.3M | 1.095% | 2026-04-01 | Morgan Stanley Smith Barney LLC Executive Financial Services |
| 2026-03-23 | KANG SUNDirector | 193K | $3.5M | 0.141% | 2026-03-23 | Morgan Stanley Smith Barney LLC Executive Financial Services |
| 2026-03-12 | STEVEN CHUBoard Seat | 156K | $2.9M | 0.114% | 2026-03-12 | Morgan Stanley Smith Barney LLC Executive Financial Services |
| 2026-03-12 | WEN HSUAN HSIEHOfficer, Director | 413K | $7.6M | 0.302% | 2026-03-12 | Morgan Stanley Smith Barney LLC Executive Financial Services |
| 2026-03-10 | STEVEN CHUBoard Seat | 167K | $3.0M | 0.122% | 2026-03-10 | Morgan Stanley Smith Barney LLC Executive Financial Services |
| 2026-02-24 | Stefan Constantin IonelOfficer | 25K | $258K | 0.019% | 2026-02-23 | Morgan Stanley Smith Barney LLC |
| 2026-02-24 | KANG SUNDirector | 61K | $622K | 0.045% | 2026-02-23 | Morgan Stanley Smith Barney LLC |
| 2026-01-21 | Stefan Constantin IonelOfficer | 717K | $8.0M | 0.550% | 2026-01-21 | Morgan Stanley Smith Barney LLC Executive Financial Services |
| 2026-01-16 | KANG SUNDirector, Officer | 1.0M | $10.3M | 0.781% | 2026-01-16 | Morgan Stanley Smith Barney LLC Executive Financial Services |
| 2026-01-12 | KANG SUNDirector, Officer | 506K | $4.8M | 0.388% | 2026-01-12 | Morgan Stanley Smith Barney LLC Executive Financial Services |
| 2025-12-11 | Stefan Constantin IonelOfficer | 198K | $2.2M | 0.152% | 2025-12-11 | Morgan Stanley Smith Barney LLC Executive Financial Services |
| 2025-11-25 | Stefan Constantin IonelOfficer | 25K | $252K | 0.019% | 2025-11-21 | Morgan Stanley Smith Barney LLC |
| 2025-11-25 | Kang SunOfficer, Director | 69K | $692K | 0.052% | 2025-11-21 | Morgan Stanley Smith Barney LLC |
| 2025-11-17 | KANG SUNDirector, Officer | 1.0M | $11.3M | 0.766% | 2025-11-17 | Morgan Stanley Smith Barney LLC Executive Financial Services |
Large holders (13D and 13G)
One row per reporting person with its latest filing, newest first. JSON1 holder reports 5% or more of AMPX in its latest filing, on Schedule 13G (passive). The holder is BlackRock, Inc. at 7.4% of the class (10,700,817 shares), filed 2026-07-27 for an event on 2026-06-30.
| Filed | Form | Holder | Shares | Of class | Event |
|---|---|---|---|---|---|
| 2026-08-10 | 13G/Ano. 1 | JANE STREET GROUP, LLCparent holding company | 4.7M | 3.3% | 2026-06-30 |
| 2026-08-10 | 13G/Ano. 1 | Jane Street Capital, LLCbroker-dealer | 3.8M | 2.7% | 2026-06-30 |
| 2026-08-10 | 13G/Ano. 1 | Jane Street Global Trading, LLCother entity | 962K | 0.7% | 2026-06-30 |
| 2026-07-27 | 13G/Ano. 1 | BlackRock, Inc.parent holding company | 10.7M | 7.4% | 2026-06-30 |
| 2026-03-26 | 13G/Ano. 1 | The Vanguard Groupinvestment adviser | 0 | 0.0% | 2026-03-13 |
13F holders
Tracked managers holding AMPX at their latest 13F. JSON7 of the 30 tracked managers held AMPX at their latest 13F, $146.9M in total at quarter-end prices. Two Sigma Investments is the largest at $59.9M (0.0% of its portfolio) as of 2026-06-30. Over the prior quarter 6 added shares and 1 cut.
| Fund | Quarter | Shares | Value | Of portfolio | Change in shares |
|---|---|---|---|---|---|
| Two Sigma Investments | 2026-06-30 | 4.3M | $59.9M | 0.04% | +813K |
| Citadel Advisors | 2026-06-30 | 1.7M | $23.2M | 0.00% | +238K |
| Renaissance Technologies | 2026-06-30 | 1.4M | $19.5M | 0.03% | +1.0M |
| Millennium Management | 2026-06-30 | 1.2M | $16.7M | 0.01% | +173K |
| Point72 Asset Management | 2026-06-30 | 1.1M | $15.8M | 0.02% | +1.1M |
| D. E. Shaw & Co. | 2026-06-30 | 672K | $9.3M | 0.00% | -404K |
| AQR Capital Management | 2026-06-30 | 173K | $2.4M | 0.00% | +35K |
Only the 30 tracked managers on the funds hub; a 13F reports long positions in US listed stock at quarter end, 45 days late, and says nothing about shorts or positions sold since.
What this page is
Amprius Technologies in the regulatory record
Regulators publish company data in separate files that never sit next to each other: FINRA's twice-monthly short interest, its daily short sale volume, the SEC's fails-to-deliver counts, and each insider's Form 4. A company page puts those series for one ticker on one URL, with planned sales, large holders, 13F holders and financials beside them, so the short position, the daily flow, the settlement fails and what insiders are doing can be read together.
Each section has its own history table, a one-line summary of the latest figures and its own JSON and CSV links, and says when its source last updated.
This page follows Amprius Technologies (AMPX), SEC CIK 1899287, listed on NYSE, classified by the SEC as miscellaneous electrical machinery, equipment & supplies. The cross-market tables live on the short interest and insider transactions hubs.
Source and updates
- Short interest
- FINRA consolidated short interestSource: FINRA.Twice a month, about eight business days after settlement. Latest 2026-10-15.JSON and CSV
- Daily short volume
- FINRA Reg SHO daily filesSource: FINRA.Every trading day, the morning after FINRA posts it. Latest 2026-11-02.JSON and CSV
- Fails to deliver
- SEC fails-to-deliver dataSource: SEC.Twice a month, a few weeks after the half month ends. Latest 2026-10-13.JSON and CSV
- Planned sales
- SEC EDGAR Form 144Source: SEC.New notices appear shortly after the SEC posts them; a notice is filed on or before the sale. Latest 2026-08-24.JSON and CSV
- Large holders
- SEC EDGAR Schedule 13D and 13GSource: SEC.New filings appear shortly after the SEC posts them. A 13D is due within five business days of crossing 5%; a 13G follows the passive schedule. Latest 2026-08-10.JSON and CSV
- 13F holders
- SEC EDGAR Form 13F-HRSource: SEC.Quarterly, filed within 45 days of quarter end; 30 tracked managers. Latest 2026-06-30.JSON and CSV
- Earnings dates
- SEC EDGAR 8-K filings (Item 2.02)Source: SEC.Twice a day. Reported dates come from the company's 8-K filings; the next date is marked as an estimate until the 8-K arrives. Latest 2026-08-04.JSON and CSV
- Insider trades
- SEC EDGAR Form 4Source: SEC.New filings appear shortly after the SEC posts them; they're due two business days after the trade. Latest 2026-08-25.JSON and CSV
- Company record
- EDGAR filing index for CIK 1899287Ticker, name and exchange from the SEC's company list, refreshed weekly.
- Rate limits
- 10 requests a minute without a key, 30 with a free key from a free account.
How to read it
- Read the position against the flow: rising short interest with a high daily short share is new shorting; rising short interest with a normal short share is old shorts holding on.
- Insider buys next to a large short position are rare and stand out; insider sells next to one are common and mean little.
- Fails to deliver matter relative to the float, not in absolute shares; a million failed shares in a mega cap is noise.
Analysis of what the data shows, not advice. XOOMAR does not recommend buying, selling or holding anything.
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Datasets
Frequently Asked Questions
How much of AMPX is sold short?
22,724,816 shares were held short at the 2026-10-15 settlement, 3.8 days of average volume. FINRA publishes the next count about eight business days after the 15th and the last business day of the month.
What is AMPX's daily short volume?
On 2026-11-02, 950,499 of the 1,755,751 AMPX shares reported to FINRA were sold short, 54.1% of the day's reported volume. Short volume is a flow for one day, not a position.
Does AMPX have fails to deliver?
The SEC's latest file shows 70 AMPX shares failed to deliver at settlement 2026-10-13. Fails are reported per settlement date and published twice a month with a lag.
Are AMPX insiders buying or selling?
Insiders at AMPX reported 4 open-market sells worth $1.3M in the last 90 days and no open-market buys. Latest filing: Stepien Thomas M (Chief Executive Officer) on 2026-08-25.
Have AMPX insiders filed to sell?
18 Form 144 notices on file for AMPX worth $83.5M at the prices reported; 1 in the last 90 days worth $80K. Latest: THOMAS M STEPIEN filed on 2026-08-24 to sell 8,000 shares ($80K) from 2026-08-24.
Who owns 5% or more of AMPX?
1 holder reports 5% or more of AMPX in its latest filing, on Schedule 13G (passive). The holder is BlackRock, Inc. at 7.4% of the class (10,700,817 shares), filed 2026-07-27 for an event on 2026-06-30.
Which tracked 13F managers own AMPX?
7 of the 30 tracked 13F managers held AMPX shares at their latest filing, $146.9M in all. The largest: Two Sigma Investments (4.3M shares, $59.9M), Ken Griffin's Citadel Advisors (1.7M shares, $23.2M), Renaissance Technologies (1.4M shares, $19.5M), Izzy Englander's Millennium Management (1.2M shares, $16.7M), Steve Cohen's Point72 Asset Management (1.1M shares, $15.8M), D. E. Shaw & Co. (672K shares, $9.3M). The table above lists all 7.
Data on this page is provided for informational purposes only and is not financial advice. See our editorial policy.