Nuclear Fusion

Commonwealth Fusion Systems

S

Private

Commonwealth Fusion Systems is building commercial fusion systems around high-temperature superconducting magnet technology developed with MIT. SPARC, its fusion-energy demonstration tokamak under construction in Devens, Massachusetts, hit ~75% completion in 2026: the first of 18 toroidal-field magnets was installed in January and the second 48-ton vacuum-vessel half arrived in May, with all 18 magnets targeted by end of summer 2026 ahead of first plasma and a Q>1 net-energy attempt in 2027. ARC, CFS' first commercial plant — officially named the Fall Line Fusion Power Station and sited on 100 acres in Chesterfield County, Virginia — became in April 2026 the first fusion project to file for grid interconnection with PJM, and on June 4, 2026 CFS published a five-paper ARC Physics Basis in the Journal of Plasma Physics projecting ~1.1 GW of fusion power and ~400 MW of net electricity. CFS has also begun monetizing its HTS magnet platform, signing a potentially multi-billion-dollar long-term magnet supply deal with Realta Fusion and launching a SPARC digital twin program with Nvidia and Siemens.

Helion Energy

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Private

Helion Energy is building fusion generators aimed at producing commercial electricity from fusion. Its Polaris prototype began operating in late 2024 and in February 2026 became the first privately developed fusion machine to demonstrate measurable deuterium-tritium fusion at 150 million degrees Celsius. Helion is now advancing Orion in Malaga, Washington, where site work began in 2025 for the company's first commercial machine intended to deliver electricity from fusion to Microsoft, while a smaller new 'Tiny Merge' testbed is being built to iterate on plasma formation faster. On June 4, 2026 Helion closed a $465M Series G led by Thrive Capital at a $15.5B post-money valuation, lifting total funding to roughly $1.5B; OpenAI is in advanced talks to buy fusion power from Helion at gigawatt scale, prompting Sam Altman to step down as board chair to recuse himself from those negotiations.

TAE Technologies

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Private (proposed TMTG merger; targeted Q4 2026 close)

TAE Technologies is a private fusion company developing hydrogen-boron fusion with a beam-driven field-reversed-configuration architecture. Its 2025 'Norm' breakthrough reduced reactor complexity enough to skip the planned Copernicus step and move directly toward Da Vinci, its first prototype power plant. In 2026 TAE completed its multi-state site evaluation tour for the first 50 MWe plant (Alabama, Ohio, Texas), formally established the TAE Beam UK joint venture with UKAEA at Culham to commercialize neutral-beam accelerator technology, and is now targeting a Q4 2026 close of its $6B all-stock merger with Trump Media & Technology Group, which in June 2026 confirmed it will no longer spin off Truth Social and other media assets ahead of the deal. TAE Power Solutions and TAE Life Sciences commercialize adjacent power-delivery and oncology technologies derived from its fusion R&D.