SoftBank's $64.6B OpenAI Bet: 13% Stake Now Complete

Ten billion dollars moved this week and the markets barely blinked. That is the unsettling part of Thursday's news out of Tokyo: SoftBank Group wired the last tranche of its $30 billion OpenAI commitment — one of the largest private investments ever made — and it landed like routine plumbing. When ten billion starts feeling like small change, you are either inside a bubble or at the start of a civilization-scale reorganization. Masayoshi Son, SoftBank's 68-year-old founder, has planted his flag in public: the latter — with $64.6 billion of shareholder money now riding on it.

On October 1, SoftBank Group said it had executed the third and final $10 billion tranche of its follow-on investment in OpenAI Group PBC through Vision Fund 2, closing out the $30 billion program announced February 27. The cumulative position now stands at $64.6 billion for roughly 13% ownership — one of the single largest stakes in the world's most important AI company. We pulled SoftBank's October 1 disclosure from its own investor site and checked the figures against Reuters; the tranche math, $10 billion at 157.96 yen to the dollar, reconciles to the yen.

Update, Oct. 2: SoftBank confirms it — the $30B program is done

SoftBank Group confirmed on October 1 that the final $10 billion tranche has been executed — $10.0 billion (¥1,579.6 billion at ¥157.96 to the dollar), funded through Vision Fund 2 and the foreign-currency senior-notes issuance announced September 24. Cumulative investment in OpenAI now stands at $64.6 billion for roughly 13% ownership, held as preferred shares that convert to common stock automatically on an IPO or listing. The March bridge is history too: the $40 billion bridge facility taken out March 27 is now fully repaid, and the remaining $10 billion of undrawn capacity was canceled on September 30. Zero bridge debt left — the early repayment SoftBank flagged on September 9 is complete.

Anatomy of the Biggest Bet in AI History

This $30 billion was never a whim. On February 27, 2026, SoftBank signed a definitive agreement with OpenAI to put up the money through follow-on investments via Vision Fund 2; a week earlier, on February 20, its board had resolved on the deal and left the final terms to CFO Yoshimitsu Goto. It was priced at a $730 billion pre-money valuation and split into three $10 billion tranches penciled in for April 1, July 1 and October 1, 2026. Thursday's announcement says the schedule held.

The securities SoftBank acquired are preferred shares that convert automatically into OpenAI common shares if the company completes an IPO or a related listing — a detail that tells you everything about where this story ends. And the $30 billion was only the follow-on. The $64.6 billion cumulative total includes roughly $34.6 billion SoftBank had already invested through Vision Fund 2 since September 2024, back when the whole position could still be assembled relatively cheaply.

That was before the money flood of this year. Earlier in 2026, OpenAI secured $122 billion in commitments at an $852 billion valuation, anchored by Amazon, Nvidia and SoftBank — one of the largest private fundraises ever recorded. In other words, Son bought early, bought big, and then bought more. “OpenAI is a clear leader, with world-class technology and an unparalleled global user base, and we have strong conviction in its continued growth,” Son said in SoftBank's February 27 disclosure announcing the deal. OpenAI's Sam Altman returned the compliment, calling SoftBank a long-term partner to help OpenAI “maximize the benefits of AI for people at global scale.”

He would say that, of course. But the compliment went both ways, in cash.

The Record-Breaking Junk-Bond Sale That Funded the Final Tranche

Here is the part of the story that should make your eyebrows move. SoftBank did not fund the final $10 billion from cash reserves or asset sales. It funded it with the proceeds of a $11.1 billion foreign-currency bond issuance whose terms were set on September 24 — the largest high-yield corporate bond sale in history, according to Reuters, surpassing French telecom Numericable's $10.9 billion issuance from 2014.

The deal split into $10 billion of dollar-denominated notes and €1 billion in euro notes. A filing showed dollar notes paying coupons of 8.625%, 9.25% and 9.75% across three maturities, with the euro tranches yielding 7.125% and 8%. SoftBank carries a BB+ rating from S&P and Fitch — the top tier of speculative grade, but still junk. For perspective, this year's biggest investment-grade issuers, Alphabet and Amazon, carry AA+ and AA ratings. SoftBank is borrowing at junk-bond rates to fund a bet the credit market still refuses to treat as investment-grade collateral.

And the bond market loved it anyway. “I was positively surprised by the market appetite,” Satoru Aoyama, senior director at Fitch Ratings, told Reuters after the sale. “Hyperscalers in the US have been raising debt but they have high credit ratings. Now AI-driven debt issuance has reached the high-yield market at scale.” This is no longer venture capital. It is infrastructure-grade financing for a new asset class, priced and sold like sovereign debt — except it is being issued by a BB+ conglomerate to buy preferred stock in a company that has never posted a public balance sheet.

The financing was layered. The $11.1 billion offering came on top of a ¥1 trillion (about $6.3 billion) retail bond issue aimed at Japanese savers earlier in September. Meanwhile, the cost of insuring SoftBank's debt against default has shot up since June, with its five-year credit default swap spread exceeding 400 basis points, up from around 280 in June and roughly 200 last October. SoftBank's own discipline holds that its loan-to-value ratio stays under 25% in normal conditions, with 35% as an emergency ceiling; at the end of June it stood at 13%. And in a sign that the bankers' bridge is behind it, SoftBank canceled the remaining $10 billion of undrawn capacity under its $40 billion bridge loan on September 30 — the facility arranged on March 27 has now been fully repaid.

For the other giant AI-money structure unveiled this week, see Broadcom's $42B chip-lease backstop for Anthropic.

Son's Conviction Borders on Theology

None of this happened by accident. It happened because Son has spent the better part of two years telling anyone who will listen that the AI skeptics are wrong, and that history will humiliate them.

Speaking at SoftBank's annual corporate conference in Tokyo in July, he dismissed bubble talk as, in his word, absurd, and projected that the development of AI would require $5 trillion of investment every year by 2040. “To ask whether AI is a bubble is a foolish question,” he told the executives in the room. “AI will transform our lives completely, and do so in a way that generates profits. Those who refuse to evolve are closing down their world. Those who condemn AI are themselves spitting upward.”

A month earlier, at the June shareholder meeting in Tokyo, he had gone further: “I think it's an insult to AI if you say it's a bubble,” he said, addressing shareholders directly. “It's just the beginning. AI's potential will be unlocked.” Then, the confession that explains the $64.6 billion: “I have become greedier. I would like to do more over the next 10 to 15 years. I will stay healthy as long as I can.” This is the man who once called SoftBank the golden-egg-laying goose and asked shareholders, with genuine exasperation, “How long do I have to fight to convince you that the goose did a good job?”

Love him or fear him, the consistency is total. Son scored one of the great wins in investing history with an early bet on Alibaba and dragged the iPhone into the Japanese market; he also detonated tens of billions on WeWork, the bankrupt shared-office provider whose name still haunts every SoftBank valuation discussion. The $64.6 billion OpenAI position is Son's attempt to render that history irrelevant — to make the Alibaba trade look like the warm-up act.

What 13% of OpenAI really means — and doesn't

A word of caution on the arithmetic, because the internet is going to get this wrong. Divide $64.6 billion by 13% and you get roughly $497 billion. That is not OpenAI's valuation. It is SoftBank's blended average cost basis, accumulated across several rounds at very different prices. The gap between those two concepts is the entire structural story: Son bought a lot of his stake cheap, and the market now values OpenAI at $852 billion in the latest round.

And the mark keeps rising. We have reported separately on OpenAI's $30 billion investor-led IPO-bridge talks at a $1.4 trillion valuation and on OpenAI's planned $1.2 trillion pre-IPO round. Take those numbers with the usual salt — a large if — but the trajectory is unmistakable: SoftBank's 13% stake, booked at $64.6 billion of cost, would be worth something like $155 to $180 billion on paper. The position gets marked to fair value every quarter, gains and losses running straight through the P&L. No wonder the reported profits for the fiscal year through March jumped nearly five-fold to ¥5 trillion — about $32 billion — per the Associated Press.

That is the machine Son has built: borrow at nine percent, buy the company everyone calls the future, mark it up every quarter, and let the paper gains drown out the interest bill. It works beautifully — until it doesn’t.

The Risk Case: What Could Break It

The honest version of this story has a dark side, and it is measured in basis points. Reuters noted in its bond-sale coverage that SoftBank's finances “could become vulnerable should market sentiment towards OpenAI and the artificial intelligence sector weaken significantly.” That is polite language for a brutal truth: a BB+ borrower paying up to 9.75% coupons to own illiquid preferred stock in a private company has no margin for a narrative break. If the AI capex story cracks — if enterprise AI revenues disappoint, if an OpenAI model release flops, if regulators move faster than the money — the position cannot be sold quickly, but the coupons keep compounding.

Son is also spending elsewhere. SoftBank is acquiring ABB's robotics business for $5.4 billion and DigitalBridge for $3.1 billion, per Reuters — the whole AI stack, chips to robots to data-center plumbing. It is a coherent vision. It is also a staggering concentration of risk in one man's thesis about the next fifteen years, financed with other people's money at junk rates. The AI trade has made plenty of geniuses this year; the trade is not yet old enough to have tested any of them. Whether Son's $64.6 billion bet pays off will decide more than SoftBank's balance sheet. It will decide whether the debt markets keep underwriting the AI buildout — because if the man who sold the biggest junk-bond deal in history to buy AI stock gets burned, every CFO in Silicon Valley will feel the chill.

On the revenue side of the ledger, OpenAI's $70B revenue run rate is the number the bull case leans on.

What Happens Now: The IPO Endgame

The endgame is already written into the documents. SoftBank's preferred shares convert automatically into OpenAI common stock if the company goes public or completes a related listing, and the tranche schedule was always subject to acceleration in the event of a listing. Every rumor of an OpenAI IPO is, in effect, a rumor about SoftBank's payday. The broader fundraising frenzy shows no sign of cooling — even the AI Startup Factory just tripled to a $5 billion valuation on the same wave of capital.

For now, though, the $30 billion program is done. The bridge loan is repaid, the bonds are sold, the preferred shares are in the vault, and Masayoshi Son owns roughly one dollar in every eight of OpenAI. He told shareholders in Tokyo he has become greedier. The $10 billion wire that crossed the Pacific this week was the proof.

The $64.6B question: what searchers actually ask

How did $64.6B add up? SoftBank invested $34.6 billion between September 2024 and early 2026 through Vision Fund 2, then added three $10 billion tranches — April 1, July 1, and October 1, 2026 — at a $730 billion pre-money valuation.

What is 13% of OpenAI actually worth? It depends on which number you believe: at the $730 billion tranche valuation it is about $95 billion on paper; at the reported $1.2 trillion pre-IPO target it would be roughly $156 billion.

How was the final tranche funded? Through the record $11.1 billion junk-bond sale — $10 billion in dollar notes plus €1 billion in euro notes, with coupons from 8.625% to 9.75% — whose proceeds were earmarked for the final tranche. The bridge facility is fully repaid.

Sources: SoftBank Group press release, October 1, 2026 (group.softbank); Reuters reporting by Arasu Kannagi Basil (Oct 1) and Anton Bridge (Sept 24); Associated Press; The Indian Express; FourWeekMBA.

By Daniel Rao, TechPulse USA
Daniel Rao covers AI, venture capital and the economics of the tech industry for TechPulse USA.

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