SoftBank shares surged nearly 19.9% to reach a session high of ¥6,039 after reports emerged that OpenAI is preparing to submit a confidential initial public offering filing with the U.S. Securities and Exchange Commission as early as Friday, May 22. The filing is said to target a public debut in the fall, although the precise timing of any listing remains uncertain.
Sources indicate OpenAI is working with Goldman Sachs and Morgan Stanley on the confidential filing. As a major shareholder holding in excess of a 10% stake in the AI firm, SoftBank stands to see its mark-to-market valuation rise materially if the marketplace re-prices OpenAI ahead of or following a public debut.
Investor optimism was further bolstered by developments at SB Energy, a SoftBank-backed venture reportedly preparing its own confidential IPO filing in the United States. SB Energy Corp. filed a Form S-1 confidentially with the SEC on May 20, 2026. The filing covers an AI infrastructure platform that spans natural gas power generation, data centers, and broader energy development activities.
Analysts noted the combined effect of the OpenAI reports and the SB Energy filing on market sentiment. Andrew Jackson, head of Japanese equity strategy at Ortus Advisors, attributed SoftBank’s sharp rally to renewed optimism about an OpenAI listing; that optimism also helped lift shares of Arm Holdings. These company-level developments came on top of SoftBank’s recent strong fundamentals - the company reported record annual profit last week, largely reflecting valuation gains tied to its OpenAI stake.
The broader Japanese equity market responded strongly. The Nikkei 225 climbed more than 3% in the session and briefly rose above 62,000 points, ending a five-session losing streak. SoftBank’s own advance accounted for about 804 points of the index’s gains. The uptick in technology-related stocks was also supported by a robust earnings report from Nvidia, which helped semiconductor-linked names gain ground.
Market participants contrasted today’s risk-on move with the pressure that weighed on equities in the prior week, when Japanese bond yields rose to historic levels - including the 30-year government bond yield breaking above 4% - and contributed to market weakness. In today’s trade, the confluence of an OpenAI IPO catalyst, the SB Energy S-1 filing, and validation of demand for AI infrastructure from Nvidia’s results produced a rare alignment of company-specific and sector-wide tailwinds.
The confluence of these factors pushed SoftBank well away from its 52-week low of ¥1,835.3 and increased its total market capitalization to approximately ¥34.5 trillion. SoftBank’s exposure to the AI sector through its stake in Arm Holdings and its investments in OpenAI leaves the group particularly sensitive to developments around AI listings and infrastructure demand.
Key takeaways
- Reports of an imminent confidential OpenAI IPO filing and SB Energy’s S-1 submission triggered substantial gains in SoftBank stock and the broader Nikkei 225.
- Nvidia’s strong earnings provided additional support for semiconductor and AI infrastructure-related equities.
- SoftBank’s recent record annual profit - driven largely by valuation gains tied to its OpenAI stake - underpins the rally.
Sectors affected: Technology, Semiconductors, Energy, Japanese Equities