SoftBank closes final $10B OpenAI tranche, lifting its total to $64.6B

SoftBank has finished paying for its slice of the largest private funding round on record. On October 1, 2026, the Japanese firm closed the third and final tranche of its $30 billion follow-on commitment to OpenAI by adding another $10 billion. That brings SoftBank’s cumulative investment in OpenAI to $64.6 billion. It also leaves the company holding an approximate 13% ownership stake in the ChatGPT maker. A social media post circulating on X said Nvidia and SoftBank had each put $10 billion into OpenAI. The SoftBank part holds up. Nvidia’s role is different: it contributed $30 billion to the February 2026 round, but it did not finalize an additional $10 billion tranche in October, despite earlier speculation that it would. The money, tranche by tranche In late February 2026, OpenAI raised between $110 billion and $122 billion. That capital came in at a pre-money valuation of approximately $730 billion. Once the new money landed, the post-money valuation reached around $840 billion to $852 billion. Three names did most of the heavy lifting. Amazon committed $50 billion, with portions of that money contingent on OpenAI hitting certain milestones. Nvidia and SoftBank each injected $3...