Goldman Sachs analysts predict a multi-trillion-dollar opportunity in nuclear energy, driven by breakthroughs in small modular reactors and fusion. Oklo and NuScale Power are the two most popular pure-play SMR stocks, though neither has built a commercial system. Oklo focuses on micro-reactors for data centers and counts OpenAI CEO Sam Altman as an early investor, while NuScale is the only U.S. company with regulatory approval to build an SMR facility and is developing projects in Romania and the U.S. Both companies have market caps well under $10 billion, and their combined valuation is close to $10 billion. The article suggests investors may benefit from owning both to gain broad exposure to SMR technology.