Few fusion startups have been as closely watched as Helion. The 12-year-old company is backed by Sam Altman, rumored to be in talks with OpenAI, and has a deal to supply Microsoft with electricity ...

Fresh off a $425 million Series F funding round, Helion is now valued at $5.4 billion, the startup announced today (Jan. 28). The company’s co-founder and CEO David Kirtley said the massive ...