Energy · Profile from Energy Research Companion
Commonwealth Fusion Systems
A private fusion company spun out of MIT's Plasma Science and Fusion Center in 2018. It has raised ~$4bn of equity (company, July 2026), more than any other private fusion developer, on one engineering bet: that magnets made from high-temperature superconducting (HTS) tape can make a tokamak far smaller and cheaper than the government machines that came before it. It proved the magnet at 20 tesla in September 2021, raised ~$1.8bn that December, and by late 2026 was finishing SPARC, a demonstration tokamak in Devens, Massachusetts that is meant to make more fusion energy than it takes to heat the plasma. First plasma is now targeted for 2027, two years later than first planned. Before SPARC has run at all, CFS has sold power from its first commercial plant: ARC, a ~400 MWe plant planned for Chesterfield County, Virginia in the early 2030s. Google has agreed to buy 200 MW (June 2025) and Eni more than $1bn of power (September 2025). In the language of this book, CFS sells a route to market for a cost it cannot yet measure, and uses those contracts to raise the matched capital that might let it measure that cost.
At a glance
- Founded
- 2018, Cambridge, Massachusetts; spin-out of the MIT Plasma Science and Fusion Center (PSFC); Eni was the first large outside investor (~$50m, March 2018, reported)
- Headquarters
- Devens, Massachusetts (SPARC site and magnet factory); offices in Cambridge, Massachusetts
- Ownership / structure
- Private, venture-backed; no single controlling holder. Investors include Tiger Global (lead, 2021), Breakthrough Energy Ventures, Bill Gates (Gates Frontier), Google, Eni, Khosla Ventures, Lowercarbon Capital, Emerson Collective, Future Ventures and, from 2025, Nvidia's NVentures, Morgan Stanley's Counterpoint Global and others (company)
- Leadership (2026)
- Bob Mumgaard (co-founder and CEO); co-founders from MIT including Brandon Sorbom (chief science officer) and Dan Brunner (verify current titles); MIT's Dennis Whyte (former PSFC director) as a founding scientific figure (reported)
- Technology
- Compact high-field tokamak; REBCO (rare-earth barium copper oxide) HTS magnets; deuterium–tritium (D-T) fuel
- Assets
- SPARC (demonstration tokamak, Devens, under construction; no electricity output by design); a magnet manufacturing line at Devens; ARC site (James River Industrial Center, Chesterfield County, Virginia; pre-construction)
- Capital raised
- ~$4bn in total (company, 30 Jul 2026): seed and Series A rounds 2018–20 (~$250m in all, reported, verify); Series B ~$1.8bn (Dec 2021); Series B2 $863m (28 Aug 2025); ~$1bn (30 Jul 2026); plus DOE and Commerce Department awards in the tens of millions of dollars
- Revenue
- No power revenue. Small revenue from magnet sales and research contracts (company, undisclosed)
- Signature moves (incl. setbacks)
- MIT spin-out and Eni investment (2018); 20-tesla magnet test and the 2021 quench damage (2021); $1.8bn Series B (2021); SPARC build and its slip from 2025 to 2027 (2021–26); fusion regulation under the byproduct-material framework (2023–24); ARC site in Virginia (2024); Google 200 MW PPA (2025); Series B2 and the Eni offtake (2025); magnet installation and the 2026 raise (2026)
9 strategic moves analysed
Each one gets a full strategy file in the companion: context, the decision, the financing, what happened, and the lesson.
2018
MIT Spin Out and Eni Investment
Founding / financing (strategic corporate investment)
2021
20 Tesla HTS Magnet Test
Technology bet / setback (test to failure)
2021
SPARC Build at Devens
Construction or commissioning / setback (schedule slip)
2021
Series B 1 8bn
Financing (growth equity)
2023
Fusion Regulation and DOE Milestones
Regulatory or legal action (industry advocacy) / financing (state support)
2024
ARC Site in Virginia
Project siting / development
2025
Google 200 MW PPA
Offtake or supply contract (plus strategic investment)
2025
Series B2 and Eni Offtake
Financing (equity) / offtake or supply contract
2026
SPARC Magnets and 1bn Raise
Construction or commissioning / financing (equity)