SoftBank Closes Final $10B OpenAI Tranche, Lifting Stake to ~13%

SoftBank Group Corp. completed its $30 billion follow-on investment in OpenAI Group PBC on October 1, 2026, bringing its cumulative stake in the AI company to $64.6 billion for an ownership interest of approximately 13%.

The third and final $10 billion tranche — JPY 1,579.6 billion at JPY 157.96 per dollar — was funded with proceeds from a foreign-currency-denominated senior notes issuance whose terms SoftBank set on September 24, 2026.

What did the February agreement commit?

SoftBank signed the definitive agreement with OpenAI on February 27, 2026 (U.S. time), committing to three $10 billion follow-on investments through Vision Fund 2 on April 1, July 1, and October 1, 2026. The deal priced OpenAI at a $730 billion pre-money valuation. The preferred shares convert automatically into OpenAI common stock upon an IPO.

Tranche dates were subject to acceleration in the event of a public listing. CFO Yoshimitsu Goto held delegated authority from the board's February 20 resolution to finalize terms. SoftBank had previously invested $34.6 billion in OpenAI through Vision Fund 2 since September 2024.

Chairman and CEO Masayoshi Son framed the follow-on as growth capital. "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 the February 27 release. CEO Sam Altman described SoftBank as "a long-term partner to help OpenAI maximize the benefits of AI for people at global scale."

How did SoftBank finance the bridge?

On March 27, 2026, SoftBank and a wholly owned overseas subsidiary entered a $40 billion unsecured bridge facility (JPY 6,384.0 billion) with JPMorgan Chase, Goldman Sachs, Mizuho Bank, Sumitomo Mitsui Banking Corporation, and MUFG Bank. The facility matured March 25, 2027.

SoftBank drew $10 billion on April 1 for the first tranche and another $10 billion on July 1 for the second. A combined $30 billion had been drawn by September 9, when SoftBank notified lenders it would prepay the remaining $25.9 billion five trading days later.

What did the senior notes cover?

On September 24, 2026, SoftBank priced approximately $11.1 billion (JPY 1,763.2 billion equivalent) of senior notes across five tranches:

• $1.0 billion due April 1, 2030 at 8.625%
• $4.5 billion due April 1, 2032 at 9.250%
• $4.5 billion due April 1, 2034 at 9.750%
• €500 million due October 1, 2030 at 7.125%
• €500 million due October 1, 2032 at 8.000%

The notes carry BB+ ratings from S&P Global Ratings Japan and Fitch Ratings Japan. They list on the Singapore Exchange, pay interest semi-annually each April 1 and October 1, and were offered in the United States, Europe, and Asia excluding Japan under Rule 144A and Regulation S. The expected issue date was September 29, 2026.

What happens to the bridge facility?

Effective September 30, 2026, SoftBank canceled the remaining $10 billion of undrawn capacity under the bridge facility. All borrowings have been repaid and no undrawn commitments remain, the company said.

SoftBank reaffirmed its financial policy framework: loan-to-value below 25% under normal conditions with a 35% emergency threshold, and cash sufficient to cover bond redemptions for at least two years. SoftBank classifies the OpenAI shares as financial assets measured at fair value through profit or loss, with quarterly remeasurement.

What does the structure signal?

SoftBank's choice to refinance a floating-rate bank facility with fixed-coupon dollar and euro notes — including a 9.75% 2034 tranche at the longest maturity it has priced — locks in the $30 billion commitment ahead of any OpenAI listing. It also absorbs the yen-cost averaging of three closing dates between JPY 158.87 and JPY 157.96 per dollar.

With the bridge retired and senior notes outstanding, the question for SoftBank's next fiscal year is whether quarterly fair value gains on the $64.6 billion stake, now convertible on any IPO, will offset the higher carry expense of the new debt stack.