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 $30 billion.

SoftBank structured its $30 billion follow-on commitment in three tranches rather than one lump sum. The October 1 payment was the last of those installments, at $10 billion. With that final tranche closed, SoftBank’s total exposure to OpenAI stands at $64.6 billion.

How OpenAI got here

OpenAI has put the proceeds toward expanding its compute and data center capabilities. Amazon’s milestone-based structure means not all of its $50 billion arrives automatically, so some of the headline figure depends on OpenAI delivering on agreed targets.

What this means

For SoftBank, the completed commitment cements one of the most concentrated bets in its portfolio. An approximate 13% stake in a company valued around $840 billion to $852 billion post-money ties a meaningful share of SoftBank’s fortunes to how OpenAI performs.

For Nvidia, its $30 billion contribution to the February round stands, and there was no additional $10 billion tranche in October. Investors tracking Nvidia’s AI exposure should anchor on that $30 billion figure, not a $10 billion add-on that did not materialize.

For Amazon, the open question is how much of its $50 billion actually flows, as portions depend on milestones.

There are several things to watch from here. The first is whether Amazon’s milestone-linked funding is released in full. The second is how quickly OpenAI’s new compute and data center capacity comes online. The third is whether the post-money valuation of around $840 billion to $852 billion holds up in any future fundraising.