Altman's Helion Stake Surges to $4.1 Billion in June 2026 After Thrive Capital Investment, Court Files Show

According to leaked court documents cited by The Wall Street Journal in the Musk v. OpenAI case, Sam Altman's personal stake in nuclear fusion company Helion surged to at least $4.1 billion in June 2026 after Thrive Capital invested in the company at a $15.5 billion valuation. The documents reveal a wealth cycle in which Altman leverages OpenAI commercial contracts to boost valuations of his personal investments, attracting high-premium investments from major OpenAI shareholders and partners.

In 2025, Altman had requested OpenAI invest approximately $500 million in Helion, a proposal the company rejected over staff concerns. Altman later stepped down from Helion's board in March 2026 to avoid conflicts. The documents also show Altman's stake in chip maker Cerebras surged over 6 times since December 2025 following OpenAI's chip procurement commitment, and his holdings in longevity startup Retro Biosciences reached $258 million by December 2025. At least 10 companies in which Altman holds stakes have transactional relationships with OpenAI.