Nuclear start-up Oklo has encountered criticism for generating no revenue in the face of triple-digit gains this year. Now the high-flying nuclear stock faces its latest test, after reporting a larger-than-expected third-quarter loss.

Oklo reported a loss of 20 cents a share for the latest quarter after the closing bell on Tuesday, compared with the loss of 13 cents a share that analysts surveyed by FactSet had expected and deeper than the loss of 8 cents a share in the year-ago third quarter.

Oklo did not report revenue, but its net loss of $29.7 million was greater than the net loss of $18.2 million analysts expected.

Shares were down 1% in late trading, after closing down 6.6%, to $104.22, in regular trading. Oklo's stock is up 391% through Tuesday's close and up 361% over the past 12 months.

Earlier in the day, the company announced that the Energy Department had approved the nuclear safety design agreement for its planned fuel fabrication facility at Idaho National Laboratory.

The plant will fabricate fuel for Oklo's first commercial-scale powerhouse, the Aurora-INL, which was selected for the DOE's Reactor Pilot Program in August. The fabrication facility itself was chosen for a separate project at the end of September.

CEO Jacob DeWitte described the development as a clear marker of progress for the company. "Advanced fuel fabrication and recycling technologies represent a significant unlock for our business, addressing fuel-supply challenges while transforming fuel economics and creating new revenue opportunities," DeWitte said.

Oklo shares have soared 409% over the past year alone, reflecting optimism for Oklo's fast reactors as well as for the broader nuclear sector in the face of ramping power demand. The stock touched an all-time closing high of $174.14 on Oct. 14 and notched its highest intraday level on record the following day.

The company has gained attention since going public in 2024, when it merged with a special purpose acquisition company headed by OpenAI CEO Sam Altman. However, with attention comes scrutiny. The company is still pre-revenue, leading many on Wall Street to question what's underpinning Oklo's meteoric rise. There are also questions about the feasibility of its timeline to deployment. To date, the company has yet to secure regulatory approval for its first nuclear power plant.

However, Oklo is steadily plodding along. In September, it broke ground on its first nuclear power plant at INL, one of 42 federally funded laboratories in the U.S. With regard to the fuel fabrication facility, it appears the company is making progress on the regulatory front, too.

Oklo has no choice but to execute: The pilot program for which it was selected aims to have at least three test reactors up and running at national laboratories across the country by July 2026. That's months, if not years, ahead of the company's own deployment targets in 2027 or 2028.

The start-up hasn't been on a smooth ride lately. Shortly after reaching new heights, shares were pummeled in a brutal selloff that also extended to peers such as Bloom Energy. In the absence of meaningful financial progress, the stock largely trades on sentiment and headlines, many of which haven't been kind.

Reports have questioned Oklo's lofty valuation and lobbed accusations of political favoritism -- former board member Chris Wright serves as Energy Secretary, though he had to recuse himself from the company as a condition of accepting the DOE position.

Earnings present another challenge: They will either signal to investors that the company is on the right path, or stoke more skepticism.

The market reacted positively to last quarter's financial results. Oklo posted a narrower loss, causing shares to rise. The company said its quarterly cash burn was in line with expectations and reiterated its targets for commercial operations.