SoftBank's SB Energy has delayed its $50 billion IPO as market fears about the AI boom intensify. The developer, backed by Masayoshi Son's group, OpenAI, and Nvidia, hoped to list at a $50 billion valuation despite having no operational data centres. The postponement follows lukewarm interest in a potential $5 billion debt sale, with investors pricing debt at roughly 10 percent yield, indicating a junk credit rating.

Concerns centre on SoftBank's heavy reliance on OpenAI as a customer, especially after the startup pledged to slow AI development for safety reasons. This delay marks the second setback for the AI sector in a week, following Holtec International's three-month listing postponement. Nvidia agreed to invest up to $105 billion in backstop funding for SB Energy's Pike County, Ohio campus, leased to OpenAI for 20 years.

SB Energy warns its data centre projects will require $174 billion in investment, primarily funded through project-level debt. The company plans to pursue the IPO and explore debt financing post-listing. OpenAI, currently valued at approximately $1.2 trillion in private funding talks, has delayed its own public offering.

SoftBank has committed over $60 billion to Sam Altman's AI start-up. Investors worry that regulatory crackdowns and political backlash against data centre construction could further curb the AI boom. SB Energy's heavy reliance on OpenAI's demand, coupled with recent safety pledges to slow model development, creates significant uncertainty for the IPO's success.