OpenAI's decision to shelve its initial public offering this year has placed its largest external shareholder, SoftBank Group Corp, squarely in the credit market's spotlight, highlighting a stark divergence in timelines: Sam Altman can afford to wait, but Masayoshi Son cannot.

During a September 13th interview with Fortune, Sam Altman clarified that despite OpenAI having confidentially filed for an IPO in June, the company will not go public this year, prioritizing instead the resolution of AI safety concerns.

This announcement has exacerbated SoftBank's liquidity challenges. Senior executives from the Japanese conglomerate are in New York this week meeting with investors, aiming to issue between $10 billion and $20 billion in bonds. The news sent SoftBank's share price plummeting nearly 11% in Tokyo on Monday, while its credit default swap spreads widened to their highest level since March.

Bloomberg estimates suggest SoftBank faces a capital shortfall of at least $20 billion, with the proceeds from this debt issuance earmarked specifically to repay the $40 billion bridge loan taken out earlier to finance its additional investment in OpenAI. Bridging this funding gap now represents the most significant test for Masayoshi Son.

IPO Expectations Dashed, Financing Pressure Mounts

The anticipated OpenAI IPO was arguably the most critical exit point in SoftBank's investment thesis. Market expectations had previously centered on an OpenAI listing as early as September with a valuation surpassing $1 trillion. SoftBank has invested approximately $64.6 billion for a stake of around 13%, and the latest funding round valued OpenAI at $852 billion.

Altman's statement has quashed these expectations, preventing SoftBank from liquidating its position in the near term, a clear risk signal for credit investors. According to Bloomberg Intelligence estimates, even after securing $10 billion via margin loans linked to its OpenAI shares and raising $6.3 billion through yen-denominated retail bonds, SoftBank's funding gap remains at least $20 billion. Should Son escalate investments in US data centers, the actual capital required would be significantly higher.

SoftBank's balance sheet structure also raises concerns among credit investors. Its venture portfolio is highly concentrated, with assets like chip designer Arm Holdings and OpenAI alone accounting for approximately 75% of its total asset value. Critically, Son financed the OpenAI stake purchase through debt, and SoftBank's recurring cash flow, such as dividends from its domestic telecom subsidiary, is now far from sufficient to cover its interest expenses.

The End of the Yen Carry Era Diminishes Cheap Financing Advantages

The yen carry trade, which has underpinned Son's investment model for decades, is losing its efficacy. Approximately half of SoftBank's interest-bearing debt is denominated in yen, while nearly all its equity assets are held in US dollars. With Japan's 10-year government bond yield rising to around 3% and the Bank of Japan expected to hike rates again this week, the cheap domestic capital Son has long relied upon is no longer readily available.

SoftBank's pivot to roadshows for institutional investors in the US is a direct reflection of this new reality. Market traders are already sensing opportunity, betting that SoftBank will need to offer generous terms to alleviate its liquidity pressures. SoftBank's existing dollar bonds are trading at pricing levels more akin to lower-rated B-grade corporate debt, significantly below its BB+ rating from Fitch. Five-year notes issued in April this year yielded over 8.5%, comparable to bonds from junk-rated data center developers like Core Scientific.

All-In Gamble or Strategic Bet? Market Questions Concentration Risk

Son's substantial bet on OpenAI has drawn market skepticism. His initial investment of $34.6 billion was made when OpenAI was valued at around $260 billion, yielding substantial paper gains. However, his additional $30 billion injection this year occurred after the valuation had significantly appreciated, further adding strain to the company's balance sheet.

This strategy contrasts sharply with industry giants like Nvidia, which favor diversification by investing in multiple competing large language model developers. Son, in contrast, has concentrated his resources on a single entity. Supporters might view this as the ultimate expression of Son's characteristic "all-in" investment philosophy, a style that has elevated him to the ranks of Japan's wealthiest individuals. However, credit market investors clearly do not share this risk appetite. They remain focused on asset concentration risks and the funding shortfall, and by demanding higher premiums, they are effectively forcing Son to pay a price for his convictions.