Short sellers have raked in an estimated $2.1bn by betting against three small‑modular‑nuclear‑reactor (SMR) companies—US‑listed Nu Scale Power, Nano Nuclear and Oklo, which is backed by Sam Altman. They profited as the market value of these stocks collapsed by $30.3bn after last year’s hype.

Investors were lured by the promise of factory‑built reactors delivering ~300MW, compared to >1,000MW for conventional plants. The boom was fueled by Trump‑era funding pledges and AI hyperscalers’ interest in new power sources. But the companies remain loss‑making, with little or no revenue.

Short sellers argue prices were inflated; Adam Stein of the Breakthrough Institute called it a textbook hype cycle. The sector faces long build‑out timelines and high capex, while regulators slow approvals. Two commercial SMRs now operate in Russia and China, but most designs are still in development.

Upcoming US listings from Holtec International and Westinghouse could test investor appetite, but sentiment has turned critical. Analysts warn of fuel shortages and uncertain delivery dates, with the earliest reactors expected only in 2028–2030. The bubble may be deflating, but the industry’s future hinges on regulatory support and capital deployment.