By Ollie Potter | Last updated: April 2026 | 9 min read

Private fusion companies have raised nearly $10 billion to date. U.S. startups captured over 75% of that capital. The sector added $2.64 billion in the year to July 2025 alone, the strongest fundraising period since 2022. Google, Chevron, Bill Gates, and Sam Altman are backing specific companies with specific timelines to deliver electricity to the grid.

The race is heating up. Commonwealth Fusion Systems is building its SPARC machine to prove net energy gain by late 2026. Helion Energy has a signed contract to deliver power to Microsoft by 2028. General Fusion nearly ran out of cash in 2025 before securing a SPAC lifeline. TAE Technologies announced a merger with Trump Media. The question is no longer who can achieve fusion in a lab. The question is who can build a commercial power plant first.

If you are watching one fusion company, watch Commonwealth Fusion Systems. They hold $3 billion in funding, more than any competitor. They are building SPARC to prove net energy gain by late 2026. They have already secured a site in Virginia for their first commercial plant. The MIT spinout has the strongest technical pedigree, the deepest investor bench (Tiger Global, Bill Gates, Google), and the most aggressive timeline among tokamak developers. Their 20-tesla HTS magnets are a genuine engineering breakthrough. If SPARC works, CFS will dominate the tokamak race.

Commonwealth Fusion Systems is building the world's most powerful tokamak magnets.

Founded: 2018 | HQ: Devens, Massachusetts | Funding: $3 billion

The MIT spinout raised $1.8 billion in November 2021, the largest fusion round ever. They added $863 million in August 2025. That is one-third of all private fusion investment globally. Tiger Global, Bill Gates, Google, and Temasek are backers.

CFS developed 20-tesla high-temperature superconducting magnets operating at -253°C. These magnets are 13 times stronger than a typical MRI. They demonstrated the technology in September 2021 and began building SPARC, their demonstration machine, in December 2021. SPARC will prove net fusion energy by late 2026. If it works, CFS will construct ARC, a 400-megawatt commercial plant in Chesterfield County, Virginia. Construction starts in 2027 or 2028.

The company announced a collaboration with NVIDIA and Siemens in 2025 to build digital twins for plasma control. CEO Bob Mumgaard sits on the Fusion Industry Association board. CFS is the tokamak leader, competing with Tokamak Energy in the UK and TAE Technologies on different fusion approaches. The Series B2 was the second-largest deep tech raise ever, after CFS's own Series B.

Sam Altman chairs the board of the only fusion company with a signed power purchase agreement.

Founded: 2013 | HQ: Everett, Washington | Funding: >$1 billion

Helion Energy raised $425 million in February 2025 at a $5.4 billion valuation. Lightspeed Venture Partners and SoftBank Vision Fund 2 led the round. Sam Altman, OpenAI's CEO, is board chair and a major investor. Helion is the only fusion company with a signed PPA. Microsoft will buy electricity from Helion's first plant in 2028.

Helion uses pulsed magneto-inertial fusion with field-reversed configuration. Unlike tokamaks, Helion generates electricity directly without steam turbines. The company operates its seventh-generation prototype, Polaris, which achieved 100 million degrees Celsius plasma temperatures in 2025. Helion broke ground on its commercial facility, Orion, in Malaga, Washington, in July 2025. The company also signed a customer agreement with Nucor for a power plant in the 2030s.

Helion targets aneutronic deuterium-helium-3 fuel, which produces less radiation than conventional fusion. Altman stepped down as board chair in April 2025 to avoid conflicts with potential OpenAI energy supply discussions. Helion is competing with Commonwealth Fusion Systems and TAE Technologies on timeline to first commercial plant. Its direct-electricity approach and Microsoft PPA give it a unique market position.

The oldest private fusion company is going public via a $6 billion merger with Trump Media.

Founded: 1998 | HQ: Foothill Ranch, California | Funding: $1.5 billion

TAE Technologies raised $150 million in June 2025 with Google, Chevron Technology Ventures, and NEA. Google has backed TAE for over a decade. The company announced a merger with Trump Media & Technology Group in December 2024 in a transaction valued above $6 billion. When the deal closes, TAE will be the first publicly traded pure-play fusion company.

TAE uses advanced beam-driven field-reversed configuration, combining accelerator physics and plasma physics. The company targets hydrogen-boron fuel, the cleanest fusion cycle. TAE published breakthrough results in Nature Communications in April 2025 showing improved reactor performance with a smaller, less complex machine called Norm. TAE has filed over 2,300 patents globally, with around 1,400 granted.

TAE collaborated with Google for over 10 years on the Optometrist Algorithm, which uses machine learning to optimize plasma. CEO Michl Binderbauer co-founded TAE at UC Irvine in the 1990s with late physicist Norman Rostoker. TAE is competing with Commonwealth Fusion Systems and Helion Energy on timeline. Its hydrogen-boron fuel choice and beam-driven approach differentiate it from tokamak and pulsed fusion competitors. The Trump Media merger surprised the industry and will provide public market access for fusion investors.

General Fusion nearly collapsed in 2025 before securing a $1 billion SPAC merger.

Founded: 2002 | HQ: Richmond, British Columbia | Funding: $440 million

General Fusion laid off over 25% of staff in May 2025 after running out of cash. CEO Christofer Mowry wrote a public plea for investment. The company secured a $30 million lifeline in August 2025 from existing backers. They announced a $1 billion SPAC merger with Spring Valley III in January 2026. The deal will provide up to $335 million in proceeds.

General Fusion uses magnetized target fusion, compressing plasma with mechanical pistons and a liquid metal liner. The company operates Lawson Machine 26, the world's first large-scale MTF demonstration machine. General Fusion achieved 100 million degrees Celsius plasma ion temperature in 2022, becoming the first private company to publish this milestone in a peer-reviewed journal. The company published a diagnostic method for LM26 in March 2026.

General Fusion was founded by physicist Michel Laberge in 2002. Backers include Canadian Nuclear Laboratories, BDC Venture Capital, and Temasek. The company's magnetized target approach differentiates it from tokamak and stellarator competitors. General Fusion struggled with fundraising compared to U.S. peers. The SPAC merger provides a path forward. If it closes before TAE's Trump Media deal, General Fusion will be the first publicly traded pure-play fusion company.

Europe's best-funded fusion startup achieved 100 million degrees Celsius in a spherical tokamak.

Founded: 2009 | HQ: Milton, Abingdon, UK | Funding: $335 million

Tokamak Energy raised $125 million in November 2024 led by East X Ventures and Lingotto Investment Management. The UK spinout from the Atomic Energy Authority holds three times more funding than Marvel Fusion, Europe's second-best funded fusion company. British Patient Capital, the UK government's investment arm, is a backer.

Tokamak Energy operates ST40, the world's highest field spherical tokamak. The company achieved 100 million degrees Celsius plasma ion temperature in 2022, the first private company to publish this milestone in a tokamak. Tokamak Energy developed a world-record 24-tesla magnetic field at 20 Kelvin with HTS magnets in 2019. The company is building Demo 4 to test magnets in fusion power plant-relevant scenarios.

Tokamak Energy commercializes HTS technology through its TE Magnetics division for motors, generators, and propulsion. This provides near-term revenue while the company develops fusion reactors. Tokamak Energy is competing with Commonwealth Fusion Systems on tokamak approach but differentiated by spherical design and HTS commercialization strategy. ST40 operated continuously for over 24 hours in 2015, demonstrating reliability.

Avalanche Energy is building desk-sized fusion reactors for space propulsion and data centers.

Founded: 2018 | HQ: Seattle, Washington | Funding: $57 million

Avalanche Energy raised $29 million in February 2026 led by RA Capital Management after achieving plasma physics breakthroughs. The company also secured a $10 million Green Jobs Grant from Washington State in July 2025. Lowercarbon Capital, Founders Fund, and Toyota Ventures are backers.

Avalanche uses compact electrostatic fusion with magneto-electrostatic confinement in a device called Orbitron. The micro-fusion reactor is desk-sized and modular. Avalanche achieved 300,000 volts in July 2025, the highest operating voltage of any fusion device since 2006. The company reached over 1 gigapascal plasma pressures on its FuZE-3 device in 2025 and completed 11,700+ Z-pinch plasmas across five devices.

Avalanche announced FusionWERX, a commercial-scale testing facility in Richland, Washington, in February 2026. FusionWERX will be the first commercial fusion test facility open to other companies. Avalanche targets space propulsion, data centers, remote power, defense, and neutron markets for near-term revenue before fusion power. The company is competing with Zap Energy on compact fusion but uses a different confinement method. Avalanche targets tritium licensing by 2027 and a Q>1 test program.

Focused Energy is building on Lawrence Livermore's 2022 ignition breakthrough with $54 million from the German government.

Founded: 2021 | HQ: Redwood City, California & Darmstadt, Germany | Funding:$175 million

Focused Energy raised $82 million in June 2023 led by Prime Movers Lab. The company also received €50 million ($54 million) from Germany's SPRIND over five years, the largest German fusion grant. The U.S. Department of Energy selected Focused Energy for a $3 million Milestone-Based Fusion Development grant in May 2023.

Focused Energy uses laser-driven inertial confinement fusion with a fast ignition approach. The company is building on Lawrence Livermore National Ignition Facility's December 2022 net energy gain breakthrough. Focused Energy collaborates with Lawrence Livermore and RWE. The company signed a $6.9 million research deal with the University of Rochester's Laboratory for Laser Energetics in March 2026.

Focused Energy targets a fusion power plant prototype by 2037. CEO Thomas Forner and CSO Markus Roth lead a German-American team with over 30 years of fusion research experience. Focused Energy benefits from five DOE INFUSE Awards for national lab collaboration. The company is competing with Xcimer, Marvel Fusion, and Pacific Fusion on laser fusion but differentiated by fast ignition approach and German infrastructure funding.

Marvel Fusion raised €113 million with backing from Siemens Energy and Deutsche Telekom.

Founded: 2019 | HQ: Munich, Germany | Funding: $400 million

Marvel Fusion raised €62.8 million in September 2024 led by HV Capital. They added €50 million in April 2025 from EQT Ventures, Siemens Energy, and the European Innovation Council Fund. Total Series B funding reached €113 million. The European Innovation Council is conducting due diligence on a potential €30 million equity investment.

Marvel Fusion uses laser-driven inertial fusion with a proprietary fast ignitor concept. The company is building on NIF's 2022 target energy gain success. Marvel Fusion has a strategic partnership with Siemens Energy for power plant technology. The company is developing alternative fuel cycles for ignition, cost-effective energy extraction, and potentially tritium-free fuel.

Marvel Fusion operates in Munich and Fort Collins, Colorado. The company advanced to the EIC STEP Scale Up due diligence phase in November 2025, one of eight selected from 36 proposals. Deutsche Telekom invested strategically for clean energy for telecom infrastructure. Marvel Fusion is competing with Focused Energy and Xcimer on laser fusion but differentiated by fast ignitor approach and Siemens partnership. The company was founded by Moritz von der Linden (CEO), Prof. Hartmut Ruhl (CSO), Heike Freund (COO), and Dr. Nicolas Burkardt (CFO).

Renaissance Fusion is simplifying stellarators with liquid metal walls and high-temperature superconductors.

Founded: 2020 | HQ: Grenoble, France | Funding: €60 million

Renaissance Fusion raised €32 million in March 2025 led by Crédit Mutuel Impact. The company also received a €10 million grant from Bpifrance in November 2023. Lowercarbon Capital led the €15.5 million seed round in May 2022. Renaissance Fusion is the first magnetic confinement fusion company in continental Europe.

Renaissance Fusion uses a stellarator design with high-temperature superconductors and liquid metal wall technology. The simplified stellarator reduces cost and complexity compared to traditional designs. The company commercializes HTS for energy generation, transmission, storage, and medical imaging to generate near-term revenue. Renaissance Fusion's proprietary liquid metal technology reduces radioactivity.

Renaissance Fusion opened a subsidiary, Renaissance Fusion Italia, in Pisa in October 2025. The company employs over 100 people from 24 nationalities and has filed 12 patent families on HTS and liquid metal technologies. Founder and CTO Francesco Volpe is a physicist with 24 years of research experience on stellarators and tokamaks. Volpe earned an Executive MBA from ESCP Europe in 2019 before founding the company. Renaissance Fusion is competing with Tokamak Energy on HTS magnets but differentiated by stellarator design.

Type One Energy is building the first U.S. stellarator with backing from Breakthrough Energy Ventures.

Founded: 2019 | HQ: Madison, Wisconsin | Funding: $82.4 million

Type One Energy raised $29 million in Series A funding in July 2024 led by Breakthrough Energy Ventures, Bill Gates's climate fund. The company also secured $53.4 million in public grants, including $46.2 million from the Tennessee Valley Authority and $5 million from the U.S. Department of Energy. Type One is building the first stellarator in the United States.

Type One uses an optimized stellarator design developed at the University of Wisconsin-Madison. Stellarators confine plasma with twisted magnetic fields without the instabilities that plague tokamaks. Type One is constructing Infinity One, a demonstration stellarator at the Oak Ridge National Laboratory campus in Tennessee. The company targets first plasma in 2028.

Type One is competing with Renaissance Fusion on stellarator approach but differentiated by U.S. operations and TVA partnership. The company benefits from decades of stellarator research at UW-Madison. Type One's Breakthrough Energy Ventures backing gives it access to Bill Gates's network and climate tech expertise. The company is the only U.S. stellarator developer with significant private funding.

The smart money is splitting between tokamaks and laser fusion. Commonwealth Fusion Systems dominates tokamaks with $3 billion and the strongest technical team. Helion Energy is the wild card with its 2028 Microsoft PPA and direct-electricity approach. TAE Technologies is betting on the cleanest fuel cycle but faces skepticism about hydrogen-boron feasibility. Laser fusion is heating up with Focused Energy and Marvel Fusion both raising over $100 million in the past year.

The underrated story is compact fusion. Avalanche Energy is building desk-sized reactors for space and data centers, targeting near-term revenue from neutron markets before fusion power. This is smarter than burning billions on gigawatt-scale plants. The overrated story is stellarators. Type One Energy and Renaissance Fusion have strong technical cases, but stellarators are decades behind tokamaks in development. The race will be won by whoever gets to grid delivery first. That is almost certainly a tokamak or pulsed fusion company. General Fusion's near-collapse in 2025 shows that even pioneering companies can run out of runway. The SPAC mergers (General Fusion, TAE) will test whether public markets have patience for fusion timelines.

Which fusion energy startup has raised the most funding? Commonwealth Fusion Systems has raised $3 billion, representing one-third of all global private fusion investment. The MIT spinout raised $1.8 billion in November 2021 and $863 million in August 2025.

When will fusion energy be commercially available? Helion Energy has a signed power purchase agreement with Microsoft targeting 2028 grid delivery. Commonwealth Fusion Systems plans to begin construction on its first commercial plant in 2027 or 2028. 84% of fusion companies believe grid delivery will occur before the 2030s end.

What is the difference between tokamak and stellarator fusion? Tokamaks use circular magnetic fields and require pulsed operation. Stellarators use twisted magnetic fields and can operate continuously. Tokamaks are further along in development, but stellarators avoid instabilities that plague tokamaks. Commonwealth Fusion Systems and Tokamak Energy are leading tokamak developers. Type One Energy and Renaissance Fusion are leading stellarator developers.

How much government funding supports fusion energy startups? The U.S. government spends $1.5 billion annually on fusion research, with $690 million directed to the private sector. The Department of Energy's Milestone-Based Fusion Development Program supports eight companies with over $46 million. China created a ¥10 billion fund, Germany committed €2 billion, and the UK committed £2.5 billion to fusion development.

Which fusion companies have achieved net energy gain? No private fusion company has achieved net energy gain yet. Lawrence Livermore National Ignition Facility achieved net energy gain in December 2022, but that was a government lab, not a startup. Commonwealth Fusion Systems is building SPARC to prove net energy gain by late 2026. Tokamak Energy and General Fusion have achieved 100 million degrees Celsius plasma temperatures, a key milestone toward net energy gain.

Join 9,000+ founders, investors, and operators. Every week: the deals, the data, and the analysis you won't find anywhere else. Subscribe free