Summary: Amprius Technologies experienced a share decline after Manatee Research published an investigative report asserting that some of the company's claimed orders, manufacturing relationships and disclosures are misleading or false. The short seller said its month-long probe - including interviews, jurisdictional corporate record checks, site visits and review of legal filings - revealed multiple concerns about Amprius's operations, accounting and partner links in the U.S., South Korea and China.
Manatee Research's report alleges a range of issues affecting Amprius's business narrative. The short seller says a key participant in the so-called "Amprius Korea Battery Alliance" is Eurocell, a company whose factory was reportedly seized by Korean prosecutors following charges of fraudulent unfair trading and failure to file a securities registration statement in January 2023. Manatee cited Korean media reports that a South Korean court handed down first-instance rulings in January 2026 against Eurocell, two affiliated entities and several executives, finding the group had imported Chinese materials or repackaged off-the-shelf products as prototypes.
The report further identifies Nanotech Energy as Amprius's U.S. manufacturing partner and notes a pattern of abandoned gigafactory plans and production announcements tied to that company across two continents. Manatee says Nanotech Energy has a four-year record of repeatedly announcing factory projects that have not materialized, and that the company has continued to import battery materials from China rather than producing domestically.
In South Korea, Manatee claims Amprius's unnamed Korean manufacturing partner announced in May 2025 is LiBest - a startup the report says posted roughly $2.6 million in sales in 2024 and received a $675,000 local government investment one month before Amprius announced its partnership.
The short seller also points to supply-chain entanglements with a Chinese supplier identified as Berzelius, which Manatee says accounted for roughly 36% of Amprius's cost of revenue in 2025. Corporate records from China and Hong Kong cited in the report indicate Berzelius is 80% held through a Hong Kong entity whose sole shareholder is Amprius Inc., registered to the same Fremont, California address listed for the public company. The remaining 20% is said to be owned by Nanjing Zhongli, which Manatee reports is 90% owned by Amprius founder, board member and former CEO Kang Sun.
Manatee raises questions about product claims and order credibility. The short seller says at least $29 million in light electric vehicle orders announced by Amprius appear to be illusory. Specifically, it notes a March announcement of a $21 million order from an unnamed Chinese customer for a battery rated at 2,000 cycles and contends that no cylindrical cell in Amprius's Q1 2026 product catalog is listed as reaching 2,000 cycles.
Accounting practices are another focal point of the report. Manatee criticizes Amprius's use of bill-and-hold accounting, under which revenue can be recorded without shipping products. The short seller highlights a sharp rise in Days Sales Outstanding and says accounts receivable at the end of Q1 2026 exceeded the quarter's reported revenue, suggesting recognition timing and collectability issues.
Corporate governance and insider activity are detailed as well. The report recounts a December 2019 lawsuit in California brought by a Singaporean investor against Tom Stepien and his prior company, Primus Power, alleging fraudulent misrepresentation and concealment after an alleged manipulation of financial data to induce a $1.5 million investment - a complaint cited by Manatee. The short seller also reports that Amprius insiders sold more than $79 million of stock between November 2025 and May 2026, and that the company's share count has expanded by roughly 55% over the past two and a half years, driven by at-the-market offerings and a May 2026 warrant exchange.
Manatee's findings reflect its month-long investigative approach, which it says included interviews with battery experts, review of entity records spanning seven jurisdictions, site visits and legal filing analysis. The report links corporate ownership structures, government investments and court rulings to construct a chain of concerns around Amprius's partner claims and disclosure practices.
Market reaction to the report was immediate: Amprius shares fell by more than 5% on the day Manatee's report was released. The short seller's allegations touch on manufacturing credibility, order veracity and accounting methods - all factors that could influence perceptions of revenue durability and balance-sheet risk for the company.
Manatee's report is a detailed set of allegations that Amprius and its purported partners have overstated capabilities and orders while employing accounting treatments that may prematurely recognize revenue. The company, its partners and relevant executives were named in specific assertions over corporate ownership, government investment timing, product capabilities and prior litigation. The report's claims underscore several areas that investors and counterparties may scrutinize further, including supplier ownership links, the basis for announced orders and the timing of revenue recognition.
What the report documents:
- Alleged involvement of Eurocell in the Amprius Korea Battery Alliance and related legal actions in South Korea.
- Identification of Nanotech Energy as a U.S. manufacturing partner with a record of unfulfilled factory announcements and reliance on Chinese imports.
- Supplier ownership structure for Berzelius and its material share of Amprius's 2025 cost of revenue.
- Questions about a reported $21 million order for a 2,000-cycle battery and the presence of such a product in Amprius's Q1 2026 catalog.
- Use of bill-and-hold accounting, rising Days Sales Outstanding and accounts receivable that exceeded Q1 2026 revenue.
- Insider sales exceeding $79 million and substantial share-count dilution over the last two and a half years.