Junk Bonds for the Machine God: SoftBank Launches $11B Debt Sale to Feed Its OpenAI Habit

On a quiet Monday — a public holiday in Japan, no less — SoftBank Group Corp quietly circulated a term sheet that says as much about the state of the AI economy in 2026 as any model release ever could. The Japanese technology investor is marketing more than $11 billion of bonds: $10 billion of dollar-denominated senior unsecured notes split across three maturities, plus €1 billion (roughly $1.1 billion) of euro notes across two tenors. Every dollar of it, ultimately, is earmarked for OpenAI.

The proceeds will cover SoftBank’s $10 billion payment on the third tranche of its follow-on investment in OpenAI, a transaction expected to close on October 1, and will refinance a $10 billion bridge facility the company secured earlier for the same purpose. Citigroup and JPMorgan are leading the deal, with pricing set for September 24 and settlement on September 29. SoftBank could not be reached for comment; the Tokyo markets were closed.

The anatomy of the deal

According to the term sheet, the dollar portion spans 3.5-year, 5.5-year and 7.5-year maturities, while the euro tranche covers 4-year and 6-year tenors. That structure is a classic ladder: near-term paper for investors who want their money back quickly, longer-dated notes for those willing to underwrite the AI bet over a full cycle.

What makes the deal remarkable is the rating. SoftBank carries a BB+ from S&P Global Ratings — the top rung of speculative grade, better known as junk. A BB+ issuer raising $11 billion in a single shot would make this one of the largest high-yield bond offerings on record. For context, that is territory normally reserved for investment-grade titans and sovereign borrowers, not a conglomerate whose financial fate is now explicitly tethered to a single private company.

How we got here

SoftBank’s OpenAI commitment has snowballed over the past year. The company executed the first tranche of its follow-on investment in April, with press materials at the time laying out plans to complete the second and third tranches — each worth $10 billion — on July 1 and October 1, 2026 respectively. The total commitment now approaches $65 billion, for a stake reported at around 13%, implying a pre-money valuation in the vicinity of $730 billion for the ChatGPT maker.

The financing machinery behind that pledge has grown correspondingly baroque. Bloomberg reported in late August that SoftBank was talking to banks about a $10–20 billion bond sale to refinance a $40 billion bridge loan tied to the OpenAI stake. Last week the company collected an $11.87 billion two-year loan, and it has already floated a record ¥1 trillion retail bond in Japan aimed at retail investors. This week’s dollar-and-euro jumbo deal is the latest — and largest — installment of that program.

There is a wrinkle, though. Sam Altman told Fortune on Friday that OpenAI will not go public in 2026 — the first on-the-record confirmation from the CEO. SoftBank shares fell 11% on the news, and the company’s OpenAI-linked borrowing for the year now tops $50 billion. Bond investors are effectively being asked to underwrite a position in a private company with no exit in sight this year.

Why it matters beyond SoftBank

The deal lands at a moment when the market is waking up to how much of the AI build-out is being financed with borrowed money. A Financial Times investigation published September 20 found that Big Tech is carrying roughly $300 billion of AI-related infrastructure exposure off balance sheets, using special-purpose vehicles that hold the debt while the parent companies backstop residual values. Alphabet’s data-center lease guarantees jumped from $16.9 billion to $43.8 billion in six months, with under 2% of the exposure booked to its balance sheet; Meta’s $50 billion Louisiana Hyperion project is structured through a Delaware SPV with roughly $28 billion of residual value guarantees supporting $27 billion of debt held by Pimco, BlackRock and Apollo.

SoftBank’s bond sale is the same phenomenon wearing a different suit. In each case, the AI capital expenditure cycle is being funded not from operating cash flow, but from debt markets — high-yield debt in SoftBank’s case, structured finance in Big Tech’s. The scale underscores how heavily AI-focused companies are leaning on credit to fund expansion, and it raises the obvious question of what happens to that stack if the revenue side of the equation disappoints.

The bull and bear cases

The bull case is straightforward: OpenAI’s revenue is scaling at a pace that makes a $730 billion valuation defensible, and SoftBank’s 13% stake could be worth multiples of the $65 billion paid. Anthropic, for comparison, is now pacing toward $100 billion in annualized revenue this year. If frontier AI keeps compounding, the interest cost on $11 billion of BB+ paper is a rounding error.

The bear case is equally crisp. SoftBank’s stock already fell 11% when the IPO timeline slipped. The company is levering its balance sheet to concentrate risk in a single private asset with no liquid exit. Its 8.5% dollar bond dropped 2.3 cents to about 98 cents earlier this month when the jumbo sale plans surfaced — the biggest daily fall since April pricing — signaling that existing creditors see dilution of their claim. And the market backdrop is not uniformly friendly: junk spreads have been grinding wider as AI-linked issuance floods the high-yield calendar.

What to watch

Three dates matter now. The bond prices on September 24 — the same day Trump and Xi meet in Washington for a summit where AI is explicitly on the agenda. Settlement follows on September 29, and the third OpenAI tranche closes on October 1. Watch the final pricing: if SoftBank has to pay a fat spread over Treasuries to clear $11 billion, it will tell you exactly how the credit market prices concentrated AI risk in late 2026.

One way or another, the money that trains the next generation of frontier models is increasingly being raised one bond covenant at a time. SoftBank just made that harder to ignore.