SoftBank Financed the Last Leg of Its OpenAI Bet With Junk-Rated Debt Paying Up to 9.75%
SoftBank Group completed the final $10 billion tranche of its $30 billion follow-on commitment to OpenAI on October 1, pushing its cumulative stake in the ChatGPT maker to roughly $64.6 billion — about 13% of a company last valued at $852 billion in a $122 billion funding round. Tokyo-listed shares fell 5.6% to ¥6,329 on the news, extending a pattern investors have shown all year: relief when SoftBank solves a financing gap, followed by renewed unease once the capital actually leaves the building.
That pattern was on full display a week earlier. None of the final tranche came from operating cash flow. On September 24, SoftBank priced $11.1 billion in senior unsecured notes — $10 billion in dollar tranches plus €1 billion in euros — on top of a ¥1 trillion (~$6.3 billion) retail bond sold to Japanese households earlier in the month. The dollar notes carried coupons of 8.625% on 3.5-year paper, 9.25% on 5.5-year paper and 9.75% on 7.5-year paper; the euro tranches priced at 7.125% and 8%. Bankers and multiple outlets described it as the largest high-yield corporate bond sale in history, eclipsing Numericable Group's $10.9 billion issuance in 2014. Shares initially jumped more than 7% on the pricing — a relief rally for a deal that was oversubscribed despite the rate — before giving most of it back once the tranche actually funded.
The rates matter because of who's paying them. SoftBank carries a BB+ rating from S&P and Ba2 from Moody's — solidly speculative grade — yet it just became the reference case for how much the market will charge an AI-exposed borrower to lever up for a minority, non-controlling equity stake. SoftBank has no confirmed board seat at OpenAI; the OpenAI Foundation retains roughly 26% ownership and board control even after $122 billion in outside capital, with Amazon ($50 billion), Nvidia ($30 billion) and Microsoft's earlier ~27% stake rounding out the cap table. The debt is senior and unsecured; the asset it bought is illiquid, non-controlling, and priced by a round SoftBank itself helped set.
A concentration problem hiding in plain sight
The largest high-yield corporate bond sale globally to date.
Credit analysts tracking the broader AI financing stack have flagged a more structural issue than any single coupon: SoftBank, Oracle and Nvidia now carry overlapping, concentrated exposure to the same private counterparty. Oracle depends on OpenAI for roughly half of its $638 billion in remaining performance obligations and sits at 4.4x adjusted leverage against a 4.5x downgrade threshold that S&P has already cited in cutting the company to BBB-. Nvidia's own OpenAI-linked guarantees reportedly carry rating-based triggers redacted from public filings. Layered against SoftBank's freshly drawn $17.4 billion of new debt, the arrangement means a single OpenAI stumble — a funding round that reprices lower, a slower-than-expected path to profitability — doesn't stay contained to one balance sheet; it propagates through at least three separately rated issuers whose credit terms were underwritten on the assumption that the platform story keeps compounding.
SoftBank also used the proceeds to close out, rather than preserve, its flexibility: the company cancelled the remaining $10 billion of undrawn capacity on a $40 billion bridge facility and confirmed all prior borrowings under it were repaid as of September 30. In other words, management chose to retire a flexible, undrawn credit line in favor of locking in nearly a decade of fixed, high-coupon obligations — a bet that today's junk-grade pricing on AI-linked debt is as good as it gets, not a temporary premium that eases once OpenAI's commercial numbers mature. For a company whose entire equity thesis now rests on one 13% stake in a private AI lab, that's a wager on the bond market's patience as much as on the model's.