Commonwealth Fusion Systems raises $863 million for SPARC and ARC development
The August 2025 Series B2 backed completion of the SPARC demonstration machine and development work on a planned commercial fusion plant.
Commonwealth Fusion Systems announced an $863 million Series B2 on 28 August 2025. The company planned to use the financing to complete its SPARC fusion demonstration machine and advance development of the ARC power plant in Virginia.
No single investor led the round. New backers included NVentures, Brevan Howard Macro Venture Fund, Counterpoint Global, Stanley Druckenmiller, Galaxy Interactive, Gigascale Capital, HOF Capital, Neva SGR and Planet First Partners.
A consortium of 12 Japanese companies, led by Mitsui & Co. and Mitsubishi Corporation, also participated. Returning investors increasing their stakes included Breakthrough Energy Ventures, Emerson Collective, Eni, Future Ventures, Gates Frontier, Google, Hostplus, Khosla Ventures, Lowercarbon Capital, Safar Partners, Eric Schmidt, Starlight Ventures and Tiger Global.
SPARC is intended to demonstrate net energy from fusion. ARC is the company’s planned grid-scale power plant; at the time of the round, CFS targeted electricity production in the early 2030s.
Use of funds
Complete the SPARC fusion demonstration machine
Advance development of the ARC power plant