Commonwealth Fusion Systems (CFS), the world’s largest and leading private nuclear fusion company, has raised $863 million in a Series B2 fundraising round as it moves closer to becoming the first company to commercialize fusion power.
The oversubscribed round is the largest among deep tech and energy companies since CFS’s $1.8 billion Series B in 2021. The funds will be used to complete SPARC, CFS’s fusion demonstration machine in Devens, Massachusetts, and advance development of the ARC power plant in Chesterfield County, Virginia. To date, CFS has raised nearly $3 billion, representing roughly one-third of all private capital invested in fusion companies worldwide.
“Investors recognize that CFS is making fusion power a reality. They see that we are executing and delivering on our objectives,” said Bob Mumgaard, CEO and co-founder of CFS. “This funding recognizes CFS’ leadership role in developing a new technology that promises to be a reliable source of clean, almost limitless energy — and will enable investors to capitalize on the birth of a new global industry.”
The Series B2 round expanded CFS’s global investor base, attracting participants from a wide range of sectors including venture capital, private equity, sovereign wealth funds, hedge funds, pension funds, industrials, and banks. Notable new investors include NVentures (Nvidia’s venture capital arm), Counterpoint Global (Morgan Stanley), Brevan Howard Macro Venture Fund, Galaxy Interactive (a venture platform within Galaxy Digital), HOF Capital, Planet First Partners, Woori Venture Partners US, and Neva SGR (Intesa Sanpaolo Bank).
A consortium of 12 Japanese companies, led by Mitsui & Co. and Mitsubishi Corporation, also participated. Members included Development Bank of Japan, JERA, Fujikura, JGC Japan, Mitsui Fudosan, NTT, Sumitomo Mitsui Banking Corporation, Sumitomo Mitsui Trust Bank, and The Kansai Electric Power Co.
Existing investors, including Breakthrough Energy Ventures, Eni, Emerson Collective, Future Ventures, Gates Frontier, Google, Khosla Ventures, Lowercarbon Capital, Safar Partners, Starlight Ventures, Tiger Global, and a large state pension fund, increased their stakes in the company, underscoring confidence in CFS’s leadership in the fusion sector.
“CFS offers investors the clearest path to bringing commercial fusion to the world — and an unprecedented opportunity to make a real impact as global demand for power accelerates with electrification and the rise of AI and data centers,” said Ally Yost, Senior Vice President of Corporate Development at CFS. “Along with energy independence and security, fusion power will expand energy access and improve quality of life globally.”
The funding round validates CFS’s position as the company with the most promising path to commercial fusion, driven by advances in high-temperature superconducting magnets and rapid progress on SPARC. The company also plans to build the world’s first grid-scale fusion power plant, ARC, in Virginia, with early partnerships with Dominion Energy and Google — which has agreed to purchase half of the plant’s output.
Investor perspectives highlight the excitement surrounding CFS:
- Dennis Lynch, Head of Counterpoint Global (Morgan Stanley), called CFS “a rare fusion of visionary leadership, scientific breakthrough, and executional excellence.”
- Vinod Khosla of Khosla Ventures praised the ARC project for its potential to fuel the age of AI.
- Laurene Powell Jobs of Emerson Collective emphasized the transformative potential of abundant, clean fusion energy.
- Hisham Elhaddad of HOF Capital and Carmichael Roberts of Breakthrough Energy Ventures highlighted the technology’s ability to reshape the global energy system.
Other investors, including Sam Englebardt of Galaxy Interactive, Frédéric de Mévius of Planet First Partners, Mario Costantini of Neva SGR, Clara Andreoletti of Eni Next, Nader Motamedy of Safar Partners, Maryanna Saenko of Future Ventures, Mike Schroepfer of Gigascale Capital, Nadim Haidar of FFA Private Bank (Dubai), and Matias Mosse of Starlight Ventures, all expressed confidence in CFS’s execution, technological innovation, and the potential of fusion power to transform global energy infrastructure.
Nuclear fusion seeks to generate energy by combining atoms, releasing vast amounts of power, in contrast to conventional nuclear fission, which splits heavy atoms like uranium. Despite decades of research, no group has yet produced more energy from a fusion reaction than the system consumes.
CFS’s SPARC project aims to achieve net energy gain, paving the way for the ARC plant to deliver grid-scale, carbon-free power by the early 2030s. The company’s rapid progress has placed it at the forefront of the race to commercialize nuclear fusion.
CFS’s successful oversubscribed round demonstrates both investor confidence and growing global interest in fusion as a solution to meet escalating energy demands, particularly in data centers and AI-driven industries, while offering the promise of nearly limitless clean energy.
