SoftBank shares plunge about 13–14% in Tokyo after AI safety scare, Bloomberg reports

SoftBank Group shares plunged about 13–14% in Tokyo Monday — among the stock’s steepest one-day drops since midsummer — after Anthropic and OpenAI leaders urged a slower frontier-AI pace and OpenAI CEO Sam Altman said a 2026 IPO would be ill-advised. SoftBank is one of OpenAI’s biggest backers, with total exposure expected to approach about $65 billion by October.

SoftBank is the clearest public-market proxy for a giant private OpenAI check — Monday’s Tokyo plunge shows how fast “pace the frontier” talk and an IPO delay scare hit the balance-sheet story, separate from the broader Asia chip session print.

Bloomberg’s Mayumi Negishi reported SoftBank Group shares slid about 13% in Tokyo Monday — the most in nearly three months. CNBC TV18, writing the same session, said the stock plunged more than 14%, its steepest one-day drop since late June. SoftBank is the Japanese tech conglomerate led by Masayoshi Son. Those are each outlet’s prints. File more than one cause: the pieces tie the selloff to AI-safety pacing talk, OpenAI IPO timing, and SoftBank’s leverage.

The same reporting says the selloff followed weekend calls by Anthropic CEO Dario Amodei and OpenAI CEO Sam Altman to slow frontier AI — the most advanced systems — for safety reasons. An IPO is the first sale of company shares to the public. Those weekend remarks and Altman’s no-2026-IPO comments are and openai-altman-no-ipo-2026. This filing is Monday’s SoftBank Tokyo print only.

CNBC TV18, and Bloomberg in the same cycle, say SoftBank is among OpenAI’s largest financial backers, with total investment in OpenAI expected to approach about $65 billion by October. These pieces do not state a precise ownership percentage.

CNBC TV18 quotes Daiwa Securities chief strategist Yugo Tsuboi: “There’s worry that OpenAI’s value may not be as high as previously expected.” He said investors were watching how much the pace of AI development could slow.

CNBC TV18 says SoftBank is planning about ¥1 trillion — about $6.5 billion — in retail bonds, and has arranged an about $10 billion loan tied to its OpenAI stake. It is also financing deals including planned acquisitions of ABB Robotics and DigitalBridge. SoftBank has not issued a primary press release about Monday’s share drop.

CNBC TV18 says SoftBank stock is down roughly 30% from its June peak. The same piece says OpenAI will not pursue a public listing in 2026, with Altman prioritizing safety work. That IPO-timing remark is already on the wire as openai-altman-no-ipo-2026.

One-sentence context: SoftBank also secured an about $11.87 billion two-year facility for its OpenAI bet from Bloomberg’s Janice Huang. This filing is the dedicated SoftBank Tokyo plunge only.