Helion, the nuclear fusion company whose main backers include Sam Altman , CEO of OpenAI , has just received a new vote of confidence from the market. According to Reuters , the company raised US$465 million in a round led by Thrive Capital , increasing its market value to US$15.5 billion.
In just over a year, the startup's valuation nearly tripled. By January 2025, the company had raised $425 million in a Series F funding round and was valued at $5.4 billion.
The race for nuclear fusion has ceased to be a project dominated by governments and has begun to attract billions of dollars from the private sector, especially from entrepreneurs and investors linked to artificial intelligence, since AI systems require increasing amounts of energy. Therefore, many industry leaders see fusion as a possible solution to sustain this demand in the long term.
In addition to Altman, Bill Gates and Nvidia have already invested in competitor Commonwealth Fusion Systems (CFS), while Google has invested in both CFS and TAE Technologies, reinforcing the growing connection between the race for artificial intelligence and the search for new energy sources.
According to the European organization Fusion for Energy, cumulative investments in merger companies jumped from US$1.7 billion in 2020 to US$15 billion in September 2025.
With this new investment, Helion has raised approximately US$1.5 billion since its founding. According to the company, the funds will be used to accelerate its business plans, expand its production capacity, and ensure future energy delivery to customers.
The new funding round, Series G, brought together investors such as Alta Park Capital, Anti Fund, BoxGroup, Lux Capital, Peak XV Partners, and Bill Ford, CEO of Ford Motor . Also participating were existing investors including Lightspeed Venture Partners, Mithril Capital, SoftBank Vision Fund 2, and Good Ventures Foundation.
The announcement comes after Helion released progress on its experimental Polaris spacecraft. According to the company, the equipment operated on fusion fuel and reached temperatures exceeding 150 million degrees Celsius, which is about ten times hotter than the sun.
To make commercial nuclear fusion power generation viable, temperatures close to 200 million degrees Celsius need to be reached. Even without having achieved that yet, Helion signed a contract in 2023 to supply electricity to Microsoft starting in 2028. It also signed a partnership with Nucor to develop a 500-megawatt fusion power plant.
Founded in 2013 by David Kirtley, John Slough, Chris Pihl, and George Votroubek, Helion is moving forward with the construction of Orion, its first power plant, which is being built in Malaga, Washington state.
