Short sellers have booked roughly $2.1 billion betting against three small modular reactor names over the past year, according to S3 Partners data, as the sector's late-2025 rally evaporates.
The trade and the numbers
NuScale Power, Nano Nuclear Energy and Sam Altman-backed Oklo, all lossmaking with minimal or no revenue, surged in 2025 as investors rushed to capture anticipated demand from AI hyperscalers hunting new power sources. Regulatory easing and funding pledges from the Trump administration added fuel. Since their collective peak in October, the trio has shed $30.3 billion in market value.
The hype cycle and its unwind
The move followed what ARR Investment Partners founder Christian Putz called a textbook hype cycle, typical for companies still in a pre-revenue phase. Only two commercial SMRs operate today, both in Russia and China, while more than 80 designs remain in development. Short sellers targeted the group on the view that shares had detached from the capital intensity and multi-year timelines required to commercialize the technology. "On the one hand there was some support from the government, and no one wants to bet against Trump, and on the other there was this whole AI demand story which everyone was really bullish about last year," Putz said. He previously shorted Oklo but has since closed the position.
Short interest stays elevated
Roughly 18 percent of Oklo and NuScale shares outstanding remain on loan, a proxy for short positions, while Nano Nuclear's loan balance sits near 30 percent, according to S&P Global Market Intelligence. The elevated levels suggest the bearish conviction persists even after the drawdown.
X-energy adds to the picture
X-energy, which went public in April backed by Amazon and Ken Griffin, has lost $5.8 billion in value since its post-IPO surge. Short sellers have captured an estimated $67 million since mid-May, per S3 Partners, with about 9 percent of shares on loan. The company has yet to secure full regulatory approval for its helium-cooled design. "The sentiment has changed this year, people are far more critical," Putz said. These businesses face almost zero revenue for the foreseeable future alongside very high capital expenditure requirements.
The demand backdrop and what comes next
U.S. data center power demand is projected by BloombergNEF to reach 106 gigawatts by 2035, up from 34.7 gigawatts last year. Big Tech is turning to nascent SMR technology to bridge the gap. In January, Meta agreed to an upfront cash injection supporting development at Oklo and Bill Gates-backed TerraPower. The Trump administration last year pledged to cut red tape and deploy tens of billions to build new reactors and restart old ones to secure energy for the AI race. In June, the Energy Department announced $17.5 billion in loans to rebuild the domestic nuclear supply chain. A key test of investor appetite arrives in coming weeks when Holtec International and Westinghouse, both with SMR divisions, are expected to list.