Helion's Real Round Is a $500M Series G at $15.5B, Not the $425M the Wires Ran
Aggregators ran a January 2025 round as new money at September's price. The real deal is a $500 million Series G that nearly triples Helion's valuation, for a deadline that now means grid connection, not delivery.
Vincent Jiang · 3 min read
The round the wires ran is 20 months old
A funding digest on October 4 told readers Helion had closed a $425 million Series F at a $15.5 billion valuation 1. Half of that sentence is 20 months stale: the $425 million Series F closed in January 2025 at a $5.4 billion post-money valuation 23. The actual new money is a $500 million Series G led by Thrive Capital, announced at $465 million in June and reopened in September for $35 million more from crossover, pension and sovereign-wealth funds 34.
2.9 times the price, no watts yet
September's $15.5 billion post-money prices Helion at 2.9 times its January 2025 mark, on roughly $1.5 billion invested to date, the second-largest private pile in fusion 23. Another $1.7 billion of Series E commitments remains milestone-conditional: promise, not cash 2. The G's new names include Lux Capital, Peak XV and Ford Motor executive chair Bill Ford, and the round is an AI-power trade, underwritten by data-center electricity demand 3. Sam Altman, the chairman who backed the company early, left its board this year as OpenAI and Helion explore working together "at significant scale" 3.
The 2028 deadline quietly changed meaning
Chief executive David Kirtley calls the moved schedule "not so much a delay as a misunderstanding": Orion connects to the grid by the end of 2028, and the 50 megawatts Microsoft contracted for arrive after a ramp-up 2. The 2023 announcement promised the plant online by 2028 at 50MW or greater following a one-year ramp, and a Helion executive has since said full capacity may not arrive until 2030 45. Constellation Energy markets the power; Nucor, an investor, wants a 500MW plant of its own 2.
The money race has a clear leader
Private fusion raised a record $4.48 billion in the year through July, up 69 percent 6. Commonwealth Fusion Systems holds $4 billion after a $1 billion July round, with Google committed to half its first plant's output 7. Type One Energy closed a $200 million Series B on October 6 toward a 400-megawatt plant it bills as the world's first 6.
Helion runs second in fusion's money race, at $1.5B against CFS's $4B
Data
| Value | |
|---|---|
| Commonwealth Fusion Systems | $4B |
| Helion | $1.5B |
| Type One Energy | $0.4B |
What the price assumes
Helion's receipts are real as far as they go: a 150-million-degree plasma in February and the first private deuterium-tritium burn 28. Only one device anywhere has hit scientific breakeven, and it is a national-lab laser, not a power plant 7. Helion's helium-3 fuel supply is also unproven at commercial scale 2. Late money is paying 2.9 times the old price for a 2028 that now means plugging in, not powering up.
What to watch
Three readings decide the trade: deuterium-helium-3 testing moving from Polaris to Orion, whether the end-2028 grid connection holds, and whether that $1.7 billion in conditional commitments converts to cash 2.
Deepdive
AI-generated from this story and its cited sources. Not investment advice.
