Commonwealth Fusion Systems Raises $863 Million Series B2 Round

Commonwealth Fusion Systems Raises $863 Million Series B2 Round

Posted on September 5, 2025 by djysrv

• Commonwealth Fusion Systems Raises $863 Million Series B2 Round

• CFS Eyes Reactor In Japan

• General Atomics Invests $20 Million in Canadian Nuclear Fusion Venture to Advance Tritium Fuel Cycle Technologies

Commonwealth Fusion Systems Raises $863 Million Series B2 Round

This round of capital is the largest raised among deep tech and energy companies since CFS’ $1.8 billion Series B round in 2021.

Commonwealth Fusion Systems (CFS), the largest and leading private fusion company,  announced that it raised $863 million in a Series B2 fundraising round as it moves closer to being the first in the world to commercialize fusion power.

The oversubscribed round of capital is the largest amount raised among deep tech and energy companies since CFS’ $1.8 billion Series B round in 2021. CFS will use the funds to complete SPARC, its fusion demonstration machine, and progress on development work on its first ARC power plant in Virginia. To date, CFS has raised close to $3 billion, about one-third of the total capital invested in private fusion companies worldwide.

The almost $3 billion that CFS has raised to date is about one-third of the total capital invested in private fusion companies worldwide, solidifying its leadership of the fusion industry.

“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.

“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 have the opportunity to capitalize on the birth of a new global industry.”

In this round, CFS expanded its global footprint by adding international investors from a widening range of sectors — from long-established fundamental investors to industrial companies. In recognition of the new category of energy technology that the company is creating, CFS deepened and broadened its access across the financial ecosystem, with investors that span venture capitalists, private equity firms, sovereign wealth funds, leading individual investors, industrials, hedge funds, pension funds and banks.

New investors in CFS include (in alphabetical order): Brevan Howard Macro Venture Fund; Counterpoint Global (Morgan Stanley); Stanley Druckenmiller; FFA Private Bank (Dubai) Ltd.; Galaxy Interactive, a venture platform within Galaxy Digital Inc. (NASDAQ: GLXY); Gigascale Capital; HOF Capital; Neva SGR (Intesa Sanpaolo Bank); NVentures (NVIDIA’s venture capital arm); Planet First Partners; Woori Venture Partners US; and others committed to the mission of commercializing fusion energy.

CFS Lists Top Priorities for the Money

In a long post on its website CFS said the top priority right now is completing SPARC — the machine that’ll demonstrate and refine core technology (Tokamak) at scale. Ther new funding lets the firm continue to push forward on that while also advancing SPARC’s successor and commercial product — the ARC fusion power plant.

In a question asked and answered the firm wrote, “How can CFS start ARC when it hasn’t even completed SPARC yet?” It’s important to note we’re not putting the cart before the horse. We have consciously structured our fundamental approach and architecture so that we aren’t constrained to working purely serially. We believe that the rate of progress is just as important as making progress, because that’s how you get to global scale and ultimately global impact. We ardently believe the fastest path to fusion is the best path for humanity. Our approach lets us  move at top speed in the race to fusion energy.”

The B2 funding brings CFS to our next phase in that race. It’s the last funding we’ll raise before SPARC reaches its first key milestone: net fusion energy, denoted scientifically as Q>1, which means producing more energy from fusion than it takes to sustain the fusion process. That’ll be a big moment in the years-long shift in perception about fusion energy moving from “impossible” to “inevitable.”

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CFS Eyes Reactor In Japan

Commonwealth Fusion Systems is looking to take its next big leap overseas. The Massachusetts startup, which just raised $863 million from investors including Nvidia (NASDAQ:NVDA), is in talks with Japanese officials about bringing its fusion technology to the country, CEO Bob Mumgaard told Bloomberg during a visit to Tokyo.

The company doesn’t yet have a working reactor, but it says interest is building. A group of 12 Japanese firms led by trading houses Mitsui & Co. and Mitsubishi Corp has already signaled support. Mumgaard said that getting a reactor running in Japan by the late 2030s or early 2040s would be a great scenario, and he plans further meetings to share updates on the global fusion race.

Fusion the process of fusing atoms together to release massive energy is seen as a clean power breakthrough, though sustaining it at scale has been notoriously difficult. Japan revised its national strategy in June to back fusion projects and wants a demonstration plant up by 2030.

Commonwealth, spun out of MIT in 2018, is also building a 400-megawatt fusion plant in Virginia, with Google (NASDAQ:GOOG) already lined up to buy half the power.

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General Atomics Invests $20 Million in Canadian Nuclear Fusion Venture to Advance Tritium Fuel Cycle Technologies

Canadian joint venture between Canadian Nuclear Laboratories (CNL) and Kyoto Fusioneering. This landmark collaboration will accelerate the development of UNITY-2, a tritium fuel cycle test facility poised to play a pivotal role in clearing the path towards commercializing fusion energy.

Scheduled to be operational by mid-2026, UNITY-2—based at Canadian Nuclear Laboratories (CNL) in Ontario—will become the world’s first fully integrated facility designed to test the deuterium-tritium (D-T) fuel cycle, a critical element for a practical fusion power plant.

Fusion, the same process that powers the sun, is widely considered a potential source of nearly limitless sustainable energy. Experts agree that a commercial D-T fusion power plant must successfully integrate four essential systems:

• a plasma confinement system (such as a tokamak or stellarator);

• a blanket system that absorbs energy from fusion reactions while producing heat and fuel;

• a fuel cycle system to recover and recycle tritium; and

• a system to convert heat into electricity.

UNITY-2 aims to tackle the complexities of the fuel cycle system by simulating the entire D-T fuel sequence—from discharge to purification and resupply. As part of the collaboration, General Atomics will leverage the facility’s advanced infrastructure to further its R&D on fusion components, while supporting the Canadian team in identifying the safest and most effective methods for handling, storing, and managing tritium. This vital work will also help lay the foundation for developing other critical fusion systems, such as a blanket component test facility to evaluate scaled prototypes of that technology.

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