The Fusion Capital Surge: Which Startups Have Crossed the $100M Mark

The fusion energy sector has undergone a dramatic transformation, pivoting from industry punchline to serious venture destination. Recent breakthroughs—particularly the Department of Energy’s 2022 controlled fusion achievement—have catalyzed a wave of private investment that continues to reshape the competitive landscape. Today, over a dozen startups have each raised nine figures or more, signaling genuine confidence that commercially viable fusion reactors are approaching reality.

The Leaders and Their Capital

Commonwealth Fusion Systems (CFS) stands atop the fundraising heap, having captured roughly one-third of all private fusion capital deployed to date. The Massachusetts-based company brought in $863 million in its August funding round, pushing cumulative raises to nearly $3 billion. CFS is engineering its Sparc tokamak to reach “commercially relevant” power levels, with operational targets set for late 2026 or early 2027. The company’s backing from Breakthrough Energy Ventures and other heavyweight investors reflects confidence in its MIT-developed superconducting magnet technology.

TAE Technologies took an unconventional path when it announced a merger with Trump Media in December 2025, valuing the combined entity at $6 billion. Before that deal, TAE had accumulated $1.79 billion through traditional venture rounds, including a $150 million injection in June from Google, Chevron, and New Enterprise. The company’s field-reversed configuration plasma confinement strategy employs particle beam bombardment to stabilize reactions.

Helion pursues the most accelerated timeline in the sector, targeting electricity generation by 2028 with Microsoft as its anchor customer. Having raised $1.03 billion total—including $425 million in January 2025—the Everett, Washington startup uses field-reversed configuration technology that directly harvests electrical current from fusion reactions. Investors backing Helion span from tech founders like Sam Altman and Peter Thiel to major institutions like BlackRock and KKR.

Pacific Fusion stunned the industry with a $900 million Series A, though funding comes in milestone-based tranches rather than lump sum. Led by Human Genome Project veteran Eric Lander, the company employs coordinated electromagnetic pulses to compress fusion fuel, requiring precisely timed outputs from 156 Marx generators.

Alternative Approaches and Specialized Players

Beyond the tokamak standard, several startups are exploring competing architectures. Proxima Fusion attracted €130 million in Series A funding for its stellarator design, which uses twisted magnetic geometry to maintain plasma stability longer than traditional ring configurations. Total raised exceeds €185 million from Balderton Capital and Cherry Ventures.

Shine Technologies ($778 million raised) is charting a pragmatic near-term revenue path through neutron testing and medical isotopes while developing long-term fusion capabilities. Zap Energy ($327 million) generates confinement magnets through electrical discharge rather than superconductors. Tokamak Energy ($336 million) compresses the tokamak geometry toward spherical shapes to reduce magnet requirements. Marvel Fusion ($162 million) employs laser-driven inertial confinement with silicon-based targets amenable to semiconductor manufacturing techniques.

Supporting Infrastructure

A critical but often overlooked category emerged as the sector matured: providers of balance of plant systems. Kyoto Fusioneering has secured $191 million to supply the peripheral equipment, heat extraction systems, and gyrotrons that convert fusion reactions into grid electricity. This positioning strategy assumes that whoever wins the technological race will need sophisticated integration partners.

General Fusion ($492 million cumulative) entered financial turbulence in 2025, laying off 25% of staff before stabilizing through emergency funding rounds totaling over $70 million. The Vancouver company pursues magnetized target fusion, using piston-driven liquid metal compression.

First Light Fusion ($108 million) similarly pivoted strategy in March 2025, abandoning proprietary power plant construction to license its projectile-based inertial confinement technology to other developers. Xcimer ($100 million) scales up the National Ignition Facility’s proven laser approach with a 10-megajoule system, five times more powerful than NIF’s breakthrough setup.

What Drives the Investment Thesis

The convergence of three enabling technologies—advanced computing, sophisticated AI control systems, and high-temperature superconducting magnets—has dramatically accelerated reactor feasibility timelines. Combined with scientific validation from DOE’s 2022 achievement, these factors have moved fusion from speculative to fundable.

The competitive heterogeneity is striking: tokamaks, stellarators, inertial confinement, field-reversed configurations, and magnetized target approaches are all receiving serious capital. This diversity suggests investors are hedging technological bets while the sector remains pre-commercial. Whether this pluralistic approach yields multiple viable pathways or eventually coalesces around dominant designs remains the trillion-dollar question.