SoftBank’s record $11.1 billion junk bond sale raises the stakes on Son’s AI bets

SoftBank Group just borrowed more money in the junk bond market than any company ever has. The Japanese conglomerate raised $11.1 billion on September 24, 2026, in the largest high-yield corporate bond issuance on record. Where is most of that cash going? Straight into OpenAI. That makes CEO Masayoshi Son’s already concentrated wager on artificial intelligence even more concentrated, and noticeably more expensive to carry. The deal by the numbers The sale knocked Numericable out of the record books. The French telecom group had held the title for the biggest junk-bond deal since 2014. Proceeds primarily covered the final $10 billion tranche of SoftBank’s $30 billion follow-on investment in OpenAI. With that payment, SoftBank’s total investment in the ChatGPT maker reaches $64.6 billion. The money buys it an approximate 13% stake. The pricing tells its own story. SoftBank sold dollar notes in three maturities, and each one came with a hefty coupon: 3.5-year notes: 8.625% 5.5-year notes: 9.25% 7.5-year notes: 9.75% Those are the highest rates SoftBank has paid in its history. All three tranches carry a BB+ rating, which sits one notch below investment grade. The package also included...