Nano Nuclear Energy (NNE -2.53%), the tiny nuclear power company developing even tinier "micro" nuclear power plants, saw its stock soar 19.8% through 1:15 p.m. ET Friday. 

The U.S. and U.K. governments agreed Thursday to cooperate in developing the two countries' artificial intelligence, quantum computing, and nuclear energy sectors, and to spend $350 billion doing so.

Glowing green nuclear radiation icon.

Image source: Getty Images.

$350 billion in total investment -- but how much for nuclear?

The British government says 150 billion pounds (US$195 billion) will be invested in the U.K., which it calls a "record-breaking investment," leaving $155 billion for the American AI, quantum, and nuclear sectors. But how much of this money goes to Nano Nuclear?

  • Britain's Urenco and America's Radiant will supply $5.3 million worth of HALEU fuel to the U.S.
  • America's X-Energy will help Britain's Centrica build "up to 12 advanced modular reactors" worth "at least 40 billion pounds."
  • Last Energy and DP World will build "one of the world's first micro modular nuclear power plants" in London.

That's all they have to say on the subject of nuclear investments -- no mention of Nano Nuclear Energy stock at all.

Is Nano Nuclear Energy stock a buy?

Fact is, the biggest beneficiary here appears to be X-Energy (and its partner Centrica). If you recall, X-Energy is a private company backed by Amazon, partnering to build several gigawatts-worth of nuclear reactors for Amazon's data centers in the Pacific Northwest.

That's good to know if you want to keep an eye on X-Energy as a potential investment, should it ever go public. But it's terrible news for investors betting on Nano Nuclear stock to benefit from the $350 billion U.S.-U.K. deal.

Nano Nuclear stock therefore remains a sell for me.