Jeff Bezos-backed fusion start-up to become first to go public
General Fusion’s ‘steampunk’ approach to the technology is under scrutiny ahead of Nasdaq debut
General Fusion is set to become the first publicly listed fusion company, even as experts question whether recent scientific results from its “steampunk” technology constitute meaningful progress towards commercialisation.
Chief executive Greg Twinney told the FT that in emerging industries first movers into the public market tended to “dominate the narrative” around what investors should expect from a commercially focused fusion company.
He added that General Fusion would have access to a “much bigger pool” of investors for future fundraising due to the lack of publicly listed rivals.
“There’s only one, that’s us.”
The Canadian company, backed by Amazon founder Jeff Bezos, who has participated in several funding rounds over the past 15 years, completed a Spac merger on Friday with Spring Valley Acquisition Corp III, valuing it at an enterprise value of $724mn and raising as much as $338mn.
Trading on the Nasdaq is due to begin on Monday.
Fusion aims to recreate the reaction that powers the Sun by fusing atomic nuclei together in superheated plasma, unlike nuclear fission, which generates energy by splitting atoms.
It has long been considered a “holy grail” of the energy industry, providing a source of low-carbon, almost limitless power, and more than 50 start-ups have been scrambling for funding.
Private fusion companies have yet to show that their fusion systems can produce more energy than is required to sustain the plasma, with the long-running joke being that fusion is “20 years away, and always will be”. But scientific breakthroughs by a US laboratory and investments by tech giants in recent years have boosted hopes among believers.
General Fusion is undergoing tests for its Lawson Machine 26 prototype in Vancouver to prove its economic viability and aims to have an operational commercial fusion plant in the mid-2030s.
The company’s listing comes as fusion companies race to secure funding for increasingly expensive machines. The number of private fusion companies has more than doubled over the past five years, intensifying competition.
A recent scientific paper published by General Fusion has raised fresh questions over whether its unconventional design is making sufficient progress towards commercial fusion, though the company says it remains confident it is on track.
Dan Brunner, at consultancy Future Tech Partners and former chief technology officer at Commonwealth Fusion Systems, said General Fusion’s recent results were “so far behind where they actually need to go” to build a commercially viable machine, adding that the company’s commercial timeline was “very hard to believe”.
Brunner said the paper showed that the company’s plasma compression failed to raise ion temperatures sufficiently, suggesting energy was still being lost through heat leakage — one of the central challenges in achieving commercial fusion power.
Most fusion start-ups are concentrating on so-called tokamak designs, which trap plasma continuously with powerful superconducting magnets. General Fusion’s process compresses magnetised plasma using a rapidly collapsing liquid-metal cavity driven by mechanical pistons — an approach Brunner described as “steampunk”.
He added that the approach posed greater uncertainty than the more established tokamaks.
Tony Donné, chair of General Fusion’s technology advisory committee and former chief executive of the European research consortium EUROfusion, disputed that assessment.
He argued that the low ion temperatures were not inherent to the design of the prototype, but instead reflected what he believed was the premature publication of the paper, as the company faced “pressure” to disclose progress ahead of its public listing.
Donné said the temperature issue had already been “investigated” and that he expected the results to improve in future tests.
This is not the first setback for one of the oldest private fusion companies. General Fusion announced in 2025 that it would lay off a quarter of its workforce after running short of funding, although Twinney said most of those employees had since been rehired following fresh investment. Multiple investors, executives and market observers also questioned whether the company chose to go public because private fundraising had become increasingly difficult.
Twinney argued that General Fusion had deliberately avoided “raising billions of dollars to build large science machines” like some rivals, instead pursuing what he described as a more capital-efficient path to commercialising fusion. “Scientific milestones are just steps along the way. They are not the end goal.”