Amprius Technologies
AMPX on NYSE. Amprius Technologies sells lithium-ion batteries with silicon anodes to drone and aircraft makers. Market value $1.4bn.
Price checks use the past 12 months to June 2026. Quality checks use five annual reports, the latest for the year to December 2025.
We can't read total debt from the filing, so debt is left out.
Should I look at this?
Not a fit for our list right now
Why it could be worth it
Nothing stands out yet.
See Technology stocks that passed both tests
This is not advice. Check the numbers below.
For every $100 of what the whole company costs, it produced $-4.23 of spare cash in the past 12 months. A savings account pays about $4.
The filings do not give us enough to work this out.
The filings do not give us enough to work this out.
Quality score: 40 of 100. Price score: 0 of 100. Our list needs 70 on quality and 60 on price.
$9.45 a share, 23% above its 1-year low
Over the past year the price has ranged from $7.71 to $24.23.
Pays no dividend
Prices from Monday’s close (5 October).
Five years of cash, in billions
Spare cash swings from quarter to quarter here: a shortfall of $58 million in the past 12 months, a shortfall of $36 million in the year to December 2025.
| Revenue | ||||
| Revenue | $4m | $9m | $24m | $73m |
| Operating margin | ||||
| Operating margin | -409.2% | -427.6% | -191.4% | -63.9% |
| Debt to equity | ||||
| Debt to equity | n/a | n/a | n/a | n/a |
| Shares outstanding | ||||
| Shares outstanding | 0.09bn | 0.11bn | 0.13bn | 0.15bn |
Health checks
- Free cash flow positive0 of 4 years
- Accounting checksSkipped: company is not yet profitable
- DebtUnknown
- Revenue growth, five yearsStrong, 154.8% a year
- Buying back its own sharesNo, 65% more shares since 2022
The quarter to June 2026
How the business did, compared with the same quarter a year earlier.
- Sales: $34 million last quarter, up 126% on a year ago.
- A loss of $3 million, compared with a loss of $6 million a year ago.
- It loses 38 cents on each $1 of sales, compared with 88 cents a year earlier.
- Over the past 12 months it spent $58 million more cash than it brought in, compared with $33 million a year earlier.
- 18% more shares than a year ago. Each share owns a bit less of the company.
- Sales grew on a year ago in each of the last 4 quarters.
| Quarter to | Amount |
|---|---|
| September 2024 | $8m |
| December 2024 | $11m |
| March 2025 | $11m |
| June 2025 | $15m |
| September 2025 | $21m |
| December 2025 | $25m |
| March 2026 | $29m |
| June 2026 | $34m |
| Quarter to | Amount |
|---|---|
| September 2024 | -$11m |
| December 2024 | -$11m |
| March 2025 | -$9m |
| June 2025 | -$6m |
| September 2025 | -$4m |
| December 2025 | -$24m |
| March 2026 | -$5m |
| June 2026 | -$3m |
From the company's quarterly reports to the SEC.
Dates
- Next results (estimated)
- n/a
- Last annual report (10-K)
- 6 March 2026
- Next quarterly (estimated, 10-Q)
- 5 November 2026
Who owns it
1 long-term investor we follow owns it, down from 2 last quarter. 262 funds in all.
| Fund | Value | Share of that fund | Change |
|---|---|---|---|
| Polen CapitalDan Davidowitz | $6m | <0.1% | Added |
Sold out this quarter
Largest holders overall
- BlackRock$157mAdded
- Vanguard Capital Management$77mAdded
- Morgan Stanley$71mAdded
- TWO Sigma Investments, LP$60mAdded
- UBS Group AG$56mAdded
- Geode Capital Management$49mAdded
- Jane Street Group$47mCut
- State Street$45mAdded
- Goldman Sachs Group$35mAdded
- Jupiter Asset Management$30mNew
From 13F filings for the quarter ended 30 June 2026.
Big holders and activists
2 investors own more than 5%.
- BlackRock, Inc.Passive investor7.4%+1.6 ptsSince 30 June 2026
- JANE STREET GROUP, LLCPassive investorat least 3.3%−1.8 pts(filed with 2 related holders)Since 30 June 2026
- SALZMAN ALAN EPassive investorSold down below 5%Since 6 August 2025
- The Vanguard GroupPassive investorSold down below 5%Since 13 March 2026
- SAIF Partners IV L.P.Passive investorSold down below 5%Since 30 June 2025
| Holder | Stake | Since | |
|---|---|---|---|
BlackRock, Inc. Passive investor | 7.4%+1.6 pts | 30 June 2026 | |
JANE STREET GROUP, LLC Passive investor | at least 3.3%−1.8 pts (filed with 2 related holders) | 30 June 2026 | |
SALZMAN ALAN E Passive investor | Sold down below 5% | 6 August 2025 | |
The Vanguard Group Passive investor | Sold down below 5% | 13 March 2026 | |
SAIF Partners IV L.P. Passive investor | Sold down below 5% | 30 June 2025 |
From Schedule 13D and 13G filings: anyone owning more than 5% must file one.
What insiders did
No insider bought shares on the open market in the last 12 months. 6 sold $86m.
- Stepien Thomas MChief Executive Officer, DirectorSold
- Date
- 24 August 2026
- Shares
- 8,000
- Price
- $10.03
- Value
- $80,240
- Stepien Thomas MChief Executive Officer, DirectorSold
- Date
- 21 August 2026
- Shares
- 23,529
- Price
- $10.34
- Value
- $243,313
- Stefan Constantin IonelChief Technology OfficerSold
- Date
- 21 August 2026
- Shares
- 29,681
- Price
- $10.34
- Value
- $306,931
- Sun KangDirectorSold
- Date
- 21 August 2026
- Shares
- 62,101
- Price
- $10.34
- Value
- $642,186
- DIXON DONALD RDirectorSold
- Date
- 15 June 2026
- Shares
- 85,000
- Price
- $17.17
- Value
- $1m
- DIXON DONALD RDirectorSold
- Date
- 9 June 2026
- Shares
- 40,000
- Price
- $19.13
- Value
- $765,200
- Stepien Thomas MChief Executive Officer, DirectorSold
- Date
- 4 June 2026
- Shares
- 2,000
- Price
- $20.97
- Value
- $41,940
- Stepien Thomas MChief Executive Officer, DirectorSold
- Date
- 27 May 2026
- Shares
- 4,375
- Price
- $17.19
- Value
- $75,206
- Stefan Constantin IonelChief Technology OfficerSold
- Date
- 27 May 2026
- Shares
- 3,208
- Price
- $17.19
- Value
- $55,146
- Sun KangDirectorSold
- Date
- 27 May 2026
- Shares
- 356
- Price
- $17.19
- Value
- $6,120
| Date | Who | Did | Shares | Price | Value |
|---|---|---|---|---|---|
| 24 August 2026 | Stepien Thomas M Chief Executive Officer, Director | Sold | 8,000 | $10.03 | $80,240 |
| 21 August 2026 | Stepien Thomas M Chief Executive Officer, Director | Sold | 23,529 | $10.34 | $243,313 |
| 21 August 2026 | Stefan Constantin Ionel Chief Technology Officer | Sold | 29,681 | $10.34 | $306,931 |
| 21 August 2026 | Sun Kang Director | Sold | 62,101 | $10.34 | $642,186 |
| 15 June 2026 | DIXON DONALD R Director | Sold | 85,000 | $17.17 | $1m |
| 9 June 2026 | DIXON DONALD R Director | Sold | 40,000 | $19.13 | $765,200 |
| 4 June 2026 | Stepien Thomas M Chief Executive Officer, Director | Sold | 2,000 | $20.97 | $41,940 |
| 27 May 2026 | Stepien Thomas M Chief Executive Officer, Director | Sold | 4,375 | $17.19 | $75,206 |
| 27 May 2026 | Stefan Constantin Ionel Chief Technology Officer | Sold | 3,208 | $17.19 | $55,146 |
| 27 May 2026 | Sun Kang Director | Sold | 356 | $17.19 | $6,120 |
From Form 4 filings: insiders must report trades in their own company's shares within two days.
Warning signs in its filings
Problems the company itself reported to the SEC, in its own words.
None of the serious warning signs we check for were found. 1 thing worth knowing.
We look for five warning signs: doubt it can keep going, weak checks on its own accounts, a notice that its past accounts can't be relied on, a change of auditor, and one customer bringing in a big share of sales. We don't check lawsuits, investigations or debt yet.
We checked the auditor's report, internal controls, restatement notices, auditor changes and big customers in the 10-K filed 6 Mar 2026, plus the 10-Q filed 6 Aug 2026 and 7 later 8-Ks.
Changed auditor
Worth knowingThe company changed its auditor (the firm that checks its books) in the last two years.
“On April 17, 2026, the Audit Committee dismissed BDO USA, P.C. ("BDO"), the Company's independent registered public accounting firm for the year ending December 31, 2025 and prior years, and notified BDO that they will not be engaged to audit the Company's consolidated financial statements for the year ending December 31, 2026.”
From an 8-K filed 21 April 2026: Change of auditor. Read it in the filing
A 10-K is the yearly report every US company files with the SEC. An 8-K is a short notice of a big event.
What could go wrong
Cheap for a reason is the question the numbers cannot answer.
Whether the price already reflects the risks is what the deep dive is for.
The deep dive
Everything above is arithmetic on public filings. The deep dive reads the last ten years of annual reports, the proxy statements, and the earnings calls, then argues the case the way Buffett, Klarman, and Hohn would, and checks every claim against the source.
- What the business is worth, as a range, and the margin of safety at today’s price
- Prices to start buying, buy, and buy hard
- The three things that would make this a mistake
- Every number footnoted to the filing it came from
Your first deep dive is free.
Not advice. Numbers on this page come from SEC filings and are updated each night; prices are updated again after the US market closes. The five-year figures are rounded.