SoftBank’s OpenAI bet: the risks behind a $64.6B leveraged stake

SoftBank Group Corp. has invested a staggering $64.6 billion in OpenAI, a significant leveraged stake that now accounts for approximately 13% of the company. The final $10 billion tranche of this investment was completed on October 1, 2026, after which SoftBank's stock price saw a 6.0% decline. This drop followed the $10 billion payment, which finalized a $30 billion program. Despite the initial positive news, this recent development has raised concerns about potential concentration risk.

The largest specific risk associated with this investment is a $10 billion loan backed by OpenAI shares. If the value of these preferred shares were to decline substantially, SoftBank would be forced to either add cash to their holdings or repay the loan early. This situation creates a dangerous loop, as owning a 13% stake in OpenAI is not inherently risky. The danger lies in the financing structure: bonds at around 9-10% rates, with a margin-call clause, all secured against an estimate of OpenAI's valuation.

The risk is compounded by the fact that rising OpenAI valuations can amplify gains, while a falling valuation could force SoftBank to raise cash or sell assets at an unfavorable time. This analysis, dated September 14, 2026, highlights the precarious position SoftBank finds itself in with its investment in OpenAI.