Oklo's loss widened in the second quarter as the company stepped up research-and-development spending and expanded its engineering and regulatory teams.

The advanced nuclear technology startup on Friday posted a widened net loss of $48.5 million, or 28 cents a share, compared with a loss of $24.7 million, or 18 cents a share, in the same quarter a year ago.

The loss widened on the back of higher research and development costs and expenses related to expanding its engineering teams and regulatory efforts.

Oklo maintained a large reserve of liquidity, and held cash, cash equivalents and marketable debt securities of $3.01 billion at quarter's end.

Revenue was $1.2 million in the quarter, compared with zero.

Oklo is working toward commercializing its metal-fueled fast reactor technology with the Aurora powerhouse product line. The company expects the line to produce between 15 and 75 megawatts of electricity on fresh, recycled or down-blended nuclear fuel, to supply clean power directly to data centers and industrial sites, while pioneering domestic fuel recycling and radioisotope production.

The company is backed by OpenAI chief executive, Sam Altman, and was the first to secure a U.S. Department of Energy site permit for a commercial advanced plant and has secured fuel allocation from the Idaho National Laboratory.

Altman was the company's chairman before stepping down from the role in mid-2025.

Oklo remains in a pre-revenue development stage, with its first commercial powerhouse targeted to go online in 2028.