The archive · Space, Robots, Defence · Technical decision · 2023–2026
Proxima Fusion bets the stellarator can win fusion; €650M+ raised, €2.4B valuation
A Max Planck spinout chose the unfashionable stellarator over the tokamak, hit milestones early, and became Europe's best-funded fusion company
Proxima Fusion
What the business is
A Munich-based fusion startup designing and building stellarator fusion power plants (Stellaris) plus an Alpha demonstration reactor, using high-temperature superconducting magnets and simulation-driven engineering
Starting capital：€20M seed (April 2024); €130M Series A (June 2025); €411M Series A2 (July 2026); more than €650M in total financing, including €95M in public grants
How it started
Proxima Fusion was founded in April 2023 as the first spin-out from the Max Planck Institute for Plasma Physics (IPP), led by physicist Francesco Sciortino. Where most fusion startups chased tokamaks, Proxima doubled down on the stellarator — the twisted-ring design behind W7-X — which needs no plasma current and runs steady-state, arguing it is the faster route to a commercial plant.
What happened
In April 2024 redalpine led a €20M seed. In 2025 Proxima and partners published Stellaris, the first peer-reviewed stellarator power-plant design integrating physics, engineering and maintenance, and closed a €130M Series A led by Balderton and Cherry Ventures — the largest private fusion round in Europe — bringing total funding past €185M and setting a 2027 Stellarator Model Coil and a 2031 Alpha demonstration as the next milestones.
How it ended up
In July 2026 Proxima closed a €411M Series A2 at a €2.4B valuation, again the largest private fusion round in Europe, with XTX Ventures and East X Ventures leading and RWE and Google as strategic investors. Bavaria pledged €400M in public funding conditional on matched private capital; total financing passed €650M, funding Alpha near Munich and the Stellaris plant at the former Gundremmingen nuclear site.
Background
Proxima Fusion was founded in April 2023 as the first spin-out from the Max Planck Institute for Plasma Physics (IPP), led by physicist Francesco Sciortino. Where most fusion startups chased tokamaks, Proxima doubled down on the stellarator — the twisted-ring design behind W7-X — which needs no plasma current and runs steady-state, arguing it is the faster route to a commercial plant.
In April 2024 redalpine led a €20M seed. In 2025 Proxima and partners published Stellaris, the first peer-reviewed stellarator power-plant design integrating physics, engineering and maintenance, and closed a €130M Series A led by Balderton and Cherry Ventures — the largest private fusion round in Europe — bringing total funding past €185M and setting a 2027 Stellarator Model Coil and a 2031 Alpha demonstration as the next milestones.
In July 2026 Proxima closed a €411M Series A2 at a €2.4B valuation, again the largest private fusion round in Europe, with XTX Ventures and East X Ventures leading and RWE and Google as strategic investors. Bavaria pledged €400M in public funding conditional on matched private capital; total financing passed €650M, funding Alpha near Munich and the Stellaris plant at the former Gundremmingen nuclear site.
What has to be true
- Being a Max Planck spinout gave Proxima decades of Wendelstein 7-X data and credibility from day one
- Publishing a peer-reviewed power-plant design turned a scientific bet into an engineering plan investors could check
- Stellarators' steady-state operation is a real technical argument, not just contrarianism: no plasma current means fewer disruptions
- Hitting milestones ahead of schedule let Proxima command oversubscribed rounds and choose strategic investors like RWE and Google
- The Bavaria €400M match signal showed public-private design can multiply private capital
What can be applied
When an industry converges on one architecture, the contrarian choice can still win capital if it ships credible, peer-reviewed milestones early — and matching public money multiplies private bets.
Aftermath
As of July 2026 Proxima had raised more than €650M (including €95M in public grants) and was valued above €2.4B, making it Europe's best-funded fusion company. It was completing the Stellarator Model Coil, scaling HTS magnet production across sites in Germany, Switzerland and the UK, and preparing Alpha, a net-energy stellarator demonstrator near Munich, with Stellaris planned for the former fission plant site at Gundremmingen later this decade.
Sources
- Proxima Fusion raises €130M Series A to build world's first stellarator-based fusion power plant in the 2030s
- Proxima Fusion joins the club of well-funded nuclear contenders with €130M Series A
- Europe's Fusion Champion Comes of Age
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