Helion, the fusion startup backed by Sam Altman, announced on Thursday that it had raised $465 million in a new funding round that values the company at $15.5 billion.
The cash infusion lands as Helion is racing to complete Orion, its first power plant. The startup has set an aggressive timeline to deploy fusion power to the grid, as early as 2028 if it can deliver on the terms of its deal with Microsoft.
The startup last raised $425 million in January 2025. Altogether, Helion said it has raised $1.5 billion.
The new round, a Series G, was led by Thrive Capital with a long list of participants, including new investors Alta Park Capital, Anti Fund, BoxGroup, Lux Capital, Peak XV Partners, and Bill Ford, along with existing investors, which include Capricorn Technology Impact Funds, Lightspeed Venture Partners, Mithril Capital, Dustin Moskovitz through Good Ventures Foundation, SoftBank Vision Fund 2, and a university endowment fund.
Helion’s approach to fusion power differs from many of its peers. Some use magnets to contain the superheated plasma required for fusion conditions, while others use lasers to compress fusion fuel until it reacts. In both cases, the majority of startups plan to use steam turbines to transform the intense heat into electricity.
But Helion, which uses magnets to compress the fuel, intends to harvest electricity straight from the magnets themselves. When fusion occurs in the plasma inside the reactor, it expands, pushing against the magnetic fields. That force can be drawn off the magnets as electricity, similar to how an electric vehicle can reverse its motors to provide braking force and recharge the battery.
Such a configuration would dramatically improve the efficiency of a fusion power plant. But some fusion experts are skeptical it could work. That’s in part because Helion, unlike many of its competitors, doesn’t frequently publish in peer-reviewed journals, so physicists haven’t been able to poke at the theoretical underpinnings. David Kirtley, Helion’s CEO, argues that eventual results from the company’s fusion devices should be sufficient. “We don’t want to theorize about fusion,” he told me last year. “We just want to go build it.”
Helion isn’t alone in attracting fresh funding. The fusion sector has become an investor darling in recent months. Focused Energy and Thea Energy both announced new rounds last week: Focused for $240 million, Thea for $100 million. In February, Inertia Energy emerged from stealth with a $450 million Series A, and the month before, Type One Energy said it was in the process of raising $250 million for a Series B.
The investments have poured in despite fusion’s lengthy timeline. Though several companies have made progress in recent months on milestones they say pave the way to a viable power plant, most predict they won’t begin operating their first commercial-scale power plant until the middle of the next decade at the earliest.
Part of the appeal is fusion’s potential to deliver nearly limitless amounts of always-on energy using little more than seawater. For AI-focused tech companies, that’s an attractive proposition. But it also has the potential to disrupt other trillion-dollar energy markets if fusion power companies can aggressively drive costs down. The timelines might be a bit longer than VCs are used to, but the potential payoff could be a lot bigger.
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Tim De Chant is a senior climate reporter at TechCrunch. He has written for a wide range of publications, including Wired magazine, the Chicago Tribune, Ars Technica, The Wire China, and NOVA Next, where he was founding editor.
De Chant is also a lecturer in MIT’s Graduate Program in Science Writing, and he was awarded a Knight Science Journalism Fellowship at MIT in 2018, during which time he studied climate technologies and explored new business models for journalism. He received his PhD in environmental science, policy, and management from the University of California, Berkeley, and his BA degree in environmental studies, English, and biology from St. Olaf College.
You can contact or verify outreach from Tim by emailing [email protected].
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Source: Techcrunch
