NEW YORK, December 29, 2025, 14:04 ET — Regular session
Oklo Inc. shares fell 3.5% to $74.24 in afternoon trading on Monday, underperforming a modestly weaker U.S. market. The stock traded between $73.90 and $78.48, with about 5.4 million shares changing hands.
The decline followed a broader pullback in U.S.-listed small modular reactor stocks after a Financial Times column flagged fresh doubts about SMR economics and deployment timelines. 1
Small modular reactors, or SMRs, are smaller nuclear units pitched as easier to manufacture and assemble than traditional large plants. The group has become a crowded “AI power” trade as data centers look for round-the-clock electricity that is not tied to weather.
That matters now because many SMR developers are still years from commercial operation, leaving sentiment and financing questions to do much of the near-term work on the share prices.
Other nuclear start-up stocks also traded lower. NuScale Power fell 2.7% and Nano Nuclear Energy slid 7.7%, while the S&P 500 tracker SPY was down 0.4% and the Nasdaq-100 tracker QQQ fell 0.6%.
Moves elsewhere in the nuclear supply chain were mixed. Uranium miner Cameco edged up 0.1% while nuclear-fuel supplier Centrus Energy slipped about 1.9%.
Oklo, backed by OpenAI chief Sam Altman, is developing fast-fission reactors—designs that operate with fast neutrons—alongside fuel recycling technologies. The company says it aims to sell heat and electricity under long-term contracts to data centers, industrial sites and government customers. 2
Investors have also watched for dilution after Oklo in early December set up an “at-the-market” program, which lets a company sell new shares into the open market over time rather than in a single block. A prospectus supplement showed the company could sell up to $1.5 billion of stock through a group of banks. 3
The next near-term policy marker comes at year-end: the U.S. Energy Department expected to begin naming by Dec. 31 which companies will receive about 19.7 metric tons of surplus Cold War-era plutonium for eventual processing into reactor fuel, Reuters reported in October. “It would be incredibly dangerous, complicated, and expensive to convert these impure plutonium materials into fuel that is safe enough for use in reactors,” said Edwin Lyman, a physicist at the Union of Concerned Scientists. 4
Analyst calendars suggest investors may not get another formal update from Oklo until late March. Zacks expects the company’s next earnings release around March 23. 5
For now, traders are watching whether the stock can stabilize after Monday’s dip and whether the sector finds new buyers once the year-end news flow passes. Any fresh announcement on customer contracts, licensing steps or capital needs would likely set the tone for OKLO in January.
