NEW YORK, May 28, 2026, 13:02 EDT
Amprius Technologies stock rallied Thursday afternoon, climbing $4.54, or roughly 26.5%, to $21.70. Trading volume crossed 13 million shares as the stock approached its session high. That performance was well ahead of the wider U.S. market, with SPY and QQQ both up less than 1%.
The rally pushed the battery maker close to a $3 billion market cap again following weeks of scrutiny. No single catalyst stands out. Instead, there’s a mix of new insider-sale filings, the short-seller report, and continued strong demand among investors for battery stocks with real top-line numbers.
Amprius hasn’t posted a new press release since May 19, when it announced a deal with Matternet, the drone-delivery firm, according to its investor-relations page. In the absence of updates, traders looked to SEC filings from May 26 and Amprius’s earlier operating update.
Amprius Technologies CEO Thomas Stepien sold 60,702 shares at an average $14.7884 on May 21, according to a Form 4 filed May 26. The filing said the trade was under a non-discretionary “sell-to-cover” plan, selling shares to pay taxes on vesting stock awards. Amprius Technologies, Inc.
Other filings showed Chief Technology Officer Stefan Constantin Ionel sold 28,812 shares, and director Sun Kang sold 67,796 shares. Both sales went through at the same average price. Restricted stock units, or RSUs, are awards that typically vest over time.
Director Donald Dixon filed a Form 144 notice for a planned sale of 17,895 shares, with a total market value of around $315,847. The filing said the stock came from restricted stock units he got as equity compensation.
Bearish bets are still in play. Last week, Manatee Research said it took a short position in Amprius, accusing the company of pumping up order numbers, failing on disclosures, and working with weak manufacturing partners; short sellers try to make money if shares drop. These are still just allegations, but they sharpened trade in a stock already popular with fast-money traders.
Amprius is betting on growth for its bull case. First-quarter revenue came in at $28.5 million, a jump of 153% year over year. Net loss shrank to $5.0 million, compared with $9.4 million last year. The company lifted its 2026 revenue forecast to at least $130 million, sticking with its goal for positive non-GAAP adjusted EBITDA. That metric cuts out interest, taxes, depreciation, amortization and other items. CEO Tom Stepien said Amprius goes into 2026 “with momentum.” Amprius Technologies, Inc.
Matternet’s May 19 deal with Amprius gave investors another sign of commercial traction. Amprius said its batteries already power Matternet’s M2 drone and the two companies are now working on new batteries for Matternet’s next-gen aircraft. “Every additional mile of range” improves network coverage, Matternet CEO Andreas Raptopoulos said. Amprius CEO Stepien said better battery performance can expand “what is possible.” Amprius Technologies, Inc.
Amprius’s latest move on capital structure is drawing attention. The company said earlier this month it will swap 2,726,631 shares for 7,128,458 public warrants. That’s 62% fewer shares than if holders had actually exercised the warrants. Warrants give buyers the right to buy shares at a preset price. The key issue for current holders is how much dilution could still be ahead.
Peers also traded up, but none matched Amprius. Enovix added around 3.8%, QuantumScape was up about 2.4%, and Solid Power tacked on roughly 3.6%. The jump in Amprius stood out from the group—this was more than just a day for battery stocks overall. Amprius broke away from the pack.
Execution is the main risk. In its 10-Q, Amprius disclosed that three customers made up 49% of its first-quarter revenue. The company said it could lose out to larger, better-funded players in aviation and EV, or to new rivals. Amprius also flagged that it may need a lot more capital spending and supply-chain upgrades to ramp production.
The stock isn’t acting like a typical industrial at the moment. Instead, it’s moving like a growth play under debate. The company’s next hurdle is showing that orders, new deals, and guidance will actually lead to delivered goods and more cash—without handing new ammo to shorts.
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