They borrowed $40B from JP Morgan. They literally did not have the money otherwise.
also they need to pay back that in one year, so if OpenAI don't IPO this year they are screwed
Was curious about the source here. Seems widely reported and I just missed it. This a unpaywalled source I found
https://techcrunch.com/2026/03/27/why-softbanks-new-40b-loan...