As tech giants turn their attention toward nuclear power for artificial intelligence and data centers, one producer is seeing its shares surge.

Oklo, a nuclear power company that counts OpenAI chief executive Sam Altman as an investor, has seen its shares climb around 150% in the past month. The stock is up almost 50% so far this year. However, during mid-day trading on Thursday, Oklo was down almost 5%.

The Santa Clara, California-based company, which has three project sites, says it’s “developing next-generation fission powerhouses to produce abundant, affordable, clean energy at a global scale.” Oklo’s Aurora powerhouse can produce 15 megawatts of electrical power (MWe), which the company says can scale up to 50 MWe and operate for ten years or longer before needing to be refueled.

Oklo’s shares have been on the up since Microsoft (MSFT) made a 20-year power purchase agreement in September with Constellation Energy (CEG) that will restart the Unit 1 reactor at Three Mile Island. Constellation, which owns most of the U.S.’s nuclear power plants, has seen its shares rise around 36% in the past month. Its stock is up 138% so far this year.

Through the Microsoft and Constellation deal, which will launch the Crane Clean Energy Center (CCEC), Microsoft will purchase energy from the Unit 1 reactor as part of its sustainability goal. The CCEC, which is expected to come online by 2028, will add more than 800 MW of carbon-free electricity to the power grid, a study by the Pennsylvania Building and Construction Trades Council found.

This week, Google (GOOGL) announced it had signed “the world’s first corporate agreement to purchase nuclear energy” from small modular reactors, or SMRs, developed by California-based Kairos Power. The tech giant said it expects to bring Kairos Power’s first SMR online by the end of the decade.

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