SoftBank Group has made an additional $10 billion investment in OpenAI Group PBC, OpenAI's for-profit arm, taking its cumulative investment to $64.6 billion. Its stake is about 13 percent. Japanese ITmedia reported on Wednesday that the investment is the third and final tranche of an additional $30 billion investment made through SoftBank Vision Fund 2.

SoftBank Group disbursed the funds in three $10 billion tranches under an agreement it signed with OpenAI on Feb. 27. The first tranche was disbursed on April 1 and the second on July 1. The third tranche completes the schedule.

The funds for the first and second investments were raised through bridge loans from major financial institutions involved in the transaction. For the final tranche, it used funds raised through corporate bond issuance.

SoftBank Group announced plans on Sept. 24 to issue dollar- and euro-denominated corporate bonds and cited the third-tranche investment funding among the uses. The total amount to be raised is about $11.1 billion. Bloomberg and other media outlets reported that it was the largest high-yield bond issuance on record among low-credit-rating companies.

The agreement also included language that the investment timing could be brought forward if an OpenAI stock listing was reasonably expected. However, CEO Sam Altman said in a September interview with U.S. business magazine Fortune that he would prioritise responding to AI safety and did not intend to pursue a listing in 2026. As a result, the investment was not brought forward and was disbursed on Oct. 1 as originally planned.