In a seismic boost for clean energy innovation, Commonwealth Fusion Systems (CFS) announced Thursday it has raised $863 million in a Series B2 funding round, calling it the largest infusion of capital for a deep tech or energy company since its record $1.8 billion Series B in 2021.

The Somerville, Massachusetts-based company, which aims to become the first to commercialize fusion power, said the funding will accelerate completion of its SPARC fusion demonstration machine and fuel development of ARC, its first grid-scale fusion power plant in Chesterfield County, Virginia.

SPARC and ARC: Toward Limitless Energy

SPARC is designed to prove the holy grail of fusion — producing net energy gain — and to chart a viable path to what CFS describes as “limitless, carbon-free power.” ARC, slated to become the world’s first fusion power station connected to the grid, already has heavyweight partners on board. Dominion Energy and Google have inked agreements to purchase half of the electricity generated at the plant.

“Investors recognize that CFS is making fusion power a reality,” said CEO and co-founder Bob Mumgaard. “This funding recognizes our leadership in developing a technology that can be a reliable, nearly limitless energy source — and gives investors a chance to back the birth of a new global industry.”

Global Investors Rush In

The round drew a wave of international backers from every corner of finance: venture capital firms, sovereign wealth funds, hedge funds, pension funds, banks, private equity, and industrial giants.

New investors include Brevan Howard Macro Venture Fund, Galaxy Interactive, NVentures, and Planet First Partners. They join long-standing supporters such as Google, Emerson Collective, Breakthrough Energy Ventures, and Starlight Ventures, who all increased their stakes.

Adding more global heft, a consortium of 12 Japanese companies led by Mitsui & Co. Ltd. and Mitsubishi Corp. also took part.

Betting on Fusion’s Future

CFS Senior Vice President of Corporate Development Ally Yost framed the raise as a watershed moment:

“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. Fusion power offers energy independence, security, and expanded access — improving quality of life worldwide.”

Next Steps

CFS is pressing forward with SPARC’s completion and laying the groundwork for ARC, which it says could redefine global energy markets. The company has not disclosed legal counsel advising on the deal, and representatives did not immediately return requests for comment.