Commonwealth Fusion Systems
MIT spinout building the SPARC compact tokamak and ARC commercial fusion pilot plant
SectorsNuclear
Capital Raised
~$2.85B+
Largest cumulative private raise in fusion history (>2x the next-largest)
HTS Magnet Record
20 Tesla
Sep 2021 TFMC test; world record for large-bore HTS magnet field strength
SPARC Q>1 Target
H1 2027
Most credible near-term timeline for net-energy fusion in the private sector
Google ARC PPA
200 MW
Jun 2025; CFS's first commercial fusion-electricity contract (delivery target early 2030s)
Funding History
Total raised: ~$2.85B+ · Latest valuation: ~$10B (Oct 2024 Series B2 reported)
| Round | Date | Amount | Valuation | Key Investors |
|---|---|---|---|---|
| Seed / Series A | 2018-2020 | ~$215M | — | Breakthrough Energy VenturesEniThe EngineKhosla Ventures+2 more |
| Series B | Dec 2021 | $1.8B | — | Tiger Global (lead)Bill GatesCoatueMarc Benioff+10 more |
| Series B2 | Oct 2024 | $863M | — | Tiger GlobalCoatueEniEquinor+4 more |
Product Specifications
| System | Type | Status |
|---|---|---|
| SPARC | Compact tokamak (50 MW thermal, Q>1 target) | Under construction at Devens, MA; first plasma target H1 2027 |
| ARC | Commercial pilot plant (400 MW gross / 200 MW net) | Site selected Chesterfield County, VA; design + procurement underway |
| HTS Magnets | High-temperature superconducting magnet family (20 T capable) | Production. CFS is the world's leading HTS-magnet manufacturer for fusion |
| Fuel Cycle / Tritium Breeding Blanket | ARC blanket and tritium handling R&D | R&D |
Partnerships & Investors
MIT Plasma Science and Fusion CenterResearch / Origin
Continuous research collaboration; SPARC physics validation work runs at MIT PSFC alongside Devens build.
GoogleInvestor / Customer
Series B + B2 investor; 200 MW ARC PPA signed Jun 2025 (CFS's first commercial fusion electricity contract).
Bill Gates / Breakthrough Energy VenturesInvestor
Cornerstone investor across all rounds; Gates personally joined Series B.
EniInvestor / Strategic
Italian oil major; anchor energy-industry investor since Series A; jointly publishing on energy-system integration.
EquinorInvestor
Norwegian state energy company; Series B + B2 investor; strategic energy-transition positioning.
Dominion EnergyHost / Offtake
Virginia utility hosting the ARC Chesterfield site; long-term offtake under negotiation alongside the Google PPA.
US Department of EnergyResearch / Cost-share
Milestone-based Public-Private Partnership program participant; HTS magnet and fuel-cycle research grants.
Key Milestones
Mar 2018
Company Founded
Spun out of MIT Plasma Science and Fusion Center by Bob Mumgaard, Dennis Whyte, Martin Greenwald, Brandon Sorbom, Zach Hartwig
Sep 2021
20 Tesla HTS Magnet Test
TFMC (Toroidal Field Model Coil) achieves 20 Tesla magnetic field strength; the largest-bore HTS magnet ever tested
Dec 2021
Series B at $1.8B
Largest fusion private round ever; Tiger Global leads; Bill Gates, Salesforce CEO Marc Benioff, John Doerr personally join
Apr 2023
Devens MA Campus Online
47-acre Devens HQ + SPARC assembly hall and magnet factory operational
Jun 2024
Chesterfield VA ARC Site
Virginia Chesterfield County selected for ARC commercial pilot plant; Dominion Energy host
Jun 2025
Google ARC PPA
Google signs 200 MW power purchase agreement for ARC Virginia (early-2030s target); CFS's first commercial fusion-electricity deal
Oct 2024
Series B2 at ~$10B
$863M raise positions for SPARC commissioning and ARC long-lead procurement
Aug 2025
SPARC Magnet Production Milestone
All 18 of SPARC's toroidal-field magnets in production at Devens; first plasma target H1 2027
2027 (target)
SPARC Q>1 Demonstration
Net energy gain from fusion demonstrated at Devens; the most consequential near-term fusion milestone
Early 2030s (target)
ARC Commercial Plant Online
400 MW gross / 200 MW net commercial pilot plant in Chesterfield County, VA