Investing.com -- Amprius Technologies saw its shares fall more than 5% on Wednesday after short seller Manatee Research released a report alleging exaggerated orders, disclosure irregularities and fraudulent manufacturing partners.

Manatee Research said its month-long investigation, which included interviews with battery experts, entity records from seven jurisdictions, site visits and legal filings, uncovered several concerns about Amprius's operations and disclosures.

The short seller claims a key member of the "Amprius Korea Battery Alliance" is Eurocell, whose factory was seized by Korean prosecutors after the company was charged with fraudulent unfair trading and failure to file a securities registration statement in January 2023. In January 2026, a South Korean court issued first-instance rulings against Eurocell, two affiliated entities and several executives, finding the group had imported Chinese materials or disguised off-the-shelf products as prototypes, according to Korean media reporting cited by Manatee.

Manatee also identified Nanotech Energy as Amprius's U.S. manufacturing partner, saying the company has left a four-year trail of abandoned gigafactory and production plan announcements across two continents and has continued to import battery materials from China.

The report claims Amprius's unnamed Korean battery manufacturer partner announced in May 2025 is LiBest, a startup that reported roughly $2.6 million in 2024 sales and received a $675,000 local government investment one month before the deal was announced.

Manatee alleges that Amprius relies on a Chinese supplier called Berzelius, which accounted for roughly 36% of its cost of revenue in 2025. Chinese and Hong Kong corporate records show Berzelius is 80% held through a Hong Kong entity whose sole shareholder is Amprius Inc., registered to the same Fremont, California address as publicly listed Amprius Technologies, according to the report. The remaining 20% is owned by Nanjing Zhongli, which is 90% owned by Amprius founder, board member and former CEO Kang Sun, Manatee said.

The short seller also raised questions about CEO Tom Stepien's previous company, Primus Power. In December 2019, a Singaporean investor sued Stepien and Primus in California, alleging eight causes of action including fraudulent misrepresentation and fraudulent concealment after Stepien induced a $1.5 million investment by manipulating financial data and concealing unfavorable information, according to the complaint cited by Manatee.

Manatee said at least $29 million in announced light electric vehicle orders appear to be illusory. In March, Amprius announced a $21 million order from an unnamed Chinese customer for a battery rated for 2,000 cycles. No cylindrical cell in Amprius's Q1 2026 product catalog reaches 2,000 cycles, the report said.

The short seller also criticized Amprius's use of bill-and-hold accounting, under which the company recognizes revenue without shipping batteries. Days Sales Outstanding have climbed sharply, and accounts receivable at the end of Q1 2026 exceeded the quarter's reported revenue, Manatee said.

Amprius insiders sold over $79 million of stock between November 2025 and May 2026, according to the report. The company's share count has grown by roughly 55% over the past two and a half years, driven by ATM offerings and the May 2026 warrant exchange, Manatee said.