 An artistic rendering of Oklo’s Aurora nuclear reactor which is being built in Idaho © Oklo
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current progress 71%
Jamie Smyth, Martha Muir and George Steer in New York and Alex Rogers in Washington
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Nuclear technology company Oklo has no revenues, no licence to operate reactors and no binding contracts to supply power.
But this has not stopped the Silicon Valley-based start-up from riding a wave of investor enthusiasm that has propelled its stock market valuation above $20bn, a rise of more than 500 per cent since the turn of the year.
The company, backed by technology boss Sam Altman and with close ties to Donald Trump’s energy secretary, has set ambitious targets to deliver commercial power to its first customers in 2027, having broken ground on its pilot in Idaho last month.
Oklo, led by the husband-and-wife team Jacob and Caroline DeWitte, envisages a future powered by a new generation of small modular reactors that use liquid sodium rather than water as a coolant.
The company is seeking to become a leader among businesses that will supply energy hungry data centres with the power they need to fuel the artificial intelligence boom.
Yet the surge in its shares, buoyed by enthusiasm from retail investors who make up an outsized proportion of its shareholders, has worried experts who fear the stock has become wildly overheated. It is among the highest valued pre-revenue businesses listed in the US.
Oklo has fallen 25 per cent over the past five trading sessions in a sign of the worries over its frothy valuation.
“It’s a pretty classic technology hype cycle,” said Adam Stein, a nuclear specialist at the Breakthrough Institute, a research group, who warned of a “bubble” in AI energy start-ups. “Most will never make it,” he said.
Oklo’s outperformance has also fed criticism from those who say it has benefited from links to Trump and from being championed by an administration that has backed it for multiple federal programmes. Trump’s energy secretary Chris Wright is a former Oklo board member.
 Oklo CEO Jacob DeWitte, second from right, in the Oval Office where President Trump pledged to quadruple US nuclear capacity by 2050 © Pool/ABACA via Reuters Connect
Trump invited DeWitte to the White House in May for an event at which the president pledged to quadruple US nuclear capacity by 2050.
Wright’s department has selected Oklo for programmes that aim to fast-track the construction of SMRs as well as nuclear fuel fabrication plants, and committed to provide it with a specialised and scarce reactor fuel.
People with knowledge of those discussions say the energy department is considering providing Oklo — named after the location in Gabon where the only natural example of nuclear fission occurred — with access to weapons-grade plutonium to make its fuel.
This relationship has helped give Oklo an edge over rivals, according to Bank of America, one reason its analysts value the business at a premium to fellow SMR developers NuScale Power and Nano Nuclear Energy.
Yet senior Democrats complain of an “appearance of impropriety” due to Wright’s time with Oklo. Ed Markey, a Democrat senator, last month hit out at the fuel deal and accused Trump’s energy secretary of aiding his former employer.
“I am concerned that your administration is moving forward with plans to transfer plutonium to Oklo and allow it to build a reprocessing plant, not because these proposals make sense for the US, but because Oklo stands to benefit financially and secretary Wright is acting in his former company’s interest,” he wrote in a letter to the president.
DeWitte, whose holding in Oklo has turned his family into paper billionaires, told the Financial Times that any suggestion the company was benefiting from political favours was “partisan bickering”.
He pointed out that Wright had recused himself from decision making regarding Oklo, and that rivals had received similar department of energy awards.
The energy department said Wright had “divested assets and resigned from board positions that may appear to present a conflict of interest” when he joined the administration. “This included resigning from the Oklo board and the forfeiture of unvested Oklo shares which he never fully owned.”
Not all are convinced by Oklo’s model.
The company has attracted the attention of short sellers, who own about 13 per cent of the stock, believing the DeWittes have underestimated the time and money required to commercialise the technology.
Some experts point to the failure of sodium-cooled reactors built in the US between 1950 and 1976. Critics also note proliferation risks because Oklo’s plans would see plutonium move into private industry hands, where it could be at risk of diversion or theft by those who seek to build an atomic bomb.
A decision by the US Nuclear Regulatory Commission to reject a previous Oklo application to build a sodium-cooled reactor in 2022 has also raised questions.
“That NRC deemed Oklo beyond help should be a red flag,” said Allison Macfarlane, a geologist and former chair at the regulator now at the University of British Columbia.
“Liquid sodium is highly corrosive, flammable and explosive on contact with air and water,” she said. “Many countries have tried to build these reactors before but they haven’t managed to prove they are commercially viable at scale.”
DeWitte, who has a PhD in nuclear engineering, wrote in a blog post published shortly after the NRC decision that the regulator’s action was “frustrating and even angering”.
He now alleges that commission staff threatened the company with retribution when Oklo challenged some of their findings over the rejection.
“That’s pretty inappropriate behaviour?.?.?. by a regulator. But nonetheless, you know, we got ourselves up, dusted ourselves off, and got back to engage with them,” said DeWitte.
He insisted sodium-cooled technology had come on leaps and bounds, and that they had a safety advantage over other types of reactors because they did not require such high pressure. This can cut costs — a factor that has previously hobbled nuclear projects.
TerraPower, the nuclear company founded by Bill Gates, and Aalo Atomics are pursuing similar technology.
DeWitte gained his doctorate from the Massachusetts Institute of Technology, where he met his wife, another nuclear engineer. They founded Oklo in 2013 and later attracted investment from Altman, who they met at the screening of a documentary on nuclear energy.
Altman served as Oklo chair and oversaw its listing last year. He left the board in April to avoid any potential conflict of interest as Oklo stepped up talks with AI companies over power contracts.
Oklo has so far signed nonbinding memorandum of understandings with Big Tech customers but no legally binding power purchase agreements, a further cause of concern for some analysts.
DeWitte said AI’s rapidly changing ecosystem made it difficult to structure deals in a way that benefited all parties. “People have been really wanting stuff signed. It’s just not in our interest to rush that until we can find the right partners and the right ways to do things,” he said.
Some in the industry are also anxious that Oklo’s eye-watering valuation and lofty public profile leave it vulnerable to a downturn in market sentiment — which could then undermine the wider nuclear renaissance.
“We’re all a little bit worried about that,” said Nick Touran, founder of the public education website What is Nuclear.
He also flagged the dangers of having an army of small shareholders as a source of finance. “Once you start running into [any] trouble, those retail investors may get spooked, and they may run a lot faster than a traditional nuclear financing arrangement would,” he said.
Share sales by Oklo executives, including the DeWittes, who own just under 18 per cent of the company, have also attracted attention. The pair made about $250mn by selling 3.2mn shares in the past six months, according to Bloomberg data analysed by the FT.
But backers of Oklo insist the momentum is unstoppable.
Michael Thompson, a venture capitalist who sits on the Oklo board, said companies operating in such “groundbreaking industries” were achieving the valuations they deserved.
“The regulatory environment is far more conducive — for the first time in a very long time — to actually making these things real,” he said.
“Capital feels more confident betting on these technologies.”
Graphics by Ian Bott
Copyright The Financial Times Limited 2025. All rights reserved.
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