Fusion power has shifted from a decades-away punchline to a technology drawing serious investor capital, with private fusion startups collectively raising $7.1 billion to date.
The bullish wave has been driven by three converging advances: more powerful computer chips, more sophisticated AI, and high-temperature superconducting magnets, which together have enabled better reactor designs, simulations, and control schemes.
Commonwealth Fusion Systems
Commonwealth Fusion Systems leads the pack, having raised roughly a third of all private fusion capital to date, nearly $3 billion, including an $863 million round in August backed by NVIDIA, Google, and Bill Gates. The company is building Sparc, a tokamak reactor in Massachusetts expected to come online in late 2026 or early 2027, ahead of Arc, a commercial 400-megawatt plant near Richmond, Virginia, with Google already committed to buying half its output.
Helion
Helion, based in Everett, Washington, has the most aggressive timeline of any fusion startup, planning to deliver electricity to its first customer, Microsoft, by 2028. The company raised $465 million in June at a $15.5 billion valuation, bringing its total funding to $1.5 billion, with backers including Sam Altman, SoftBank, Reid Hoffman, and Peter Thiel.
Pacific Fusion, Shine Technologies & General Fusion
Other major players include Pacific Fusion, which raised over $1 billion in its Series A under CEO Eric Lander, the former Human Genome Project leader, and TAE Technologies, which announced a $6 billion merger with Trump Media & Technology Group in December. Shine Technologies has taken a pragmatic approach, generating revenue from neutron testing and medical isotopes while it raised $1 billion total. General Fusion struggled financially in 2025, laying off 25% of its staff before securing emergency funding and announcing plans to go public via reverse merger.
Others
Smaller but well-funded entrants include Inertia Enterprises, founded by National Ignition Facility veterans with $450 million raised; Xcimer, which recently activated the world’s most powerful privately owned laser; and stellarator-focused startups Proxima Fusion and Thea Energy, both betting on alternative reactor geometries to reduce magnet costs.
It should also be noted here that at the end of 2022, a U.S. Department of Energy lab announced that it had produced a controlled fusion reaction that produced more power than the lasers had imparted to the fuel pellet.
