SoftBank shares tumble 13% as OpenAI, Anthropic raise AI safety alarm

Shares of SoftBank Group Corp plunged over 13% on Monday on the Tokyo Stock Exchange. The stock fell 13.18% to 6540 Japanese Yen against the previous close of 5678 Japanese Yen. Market cap of the  Japanese multinational investment holding company slipped to 33.316 trillion Japanese Yen.

The fall in the Japanese market behemoth came as growing concerns over the pace of artificial intelligence development added to investor anxiety surrounding the Japanese technology conglomerate’s aggressive AI strategy.

The sell-off came after the heads of Anthropic PBC and OpenAI called for greater caution in the development of advanced AI systems, urging developers to slow down amid rising safety concerns. The comments have added to uncertainty around the future trajectory of the AI industry and intensified scrutiny of SoftBank’s heavy exposure to the sector.

SoftBank is among the largest backers of OpenAI, with its total investment in the ChatGPT developer expected to approach $65 billion by October. The scale of that commitment has made the Japanese group particularly sensitive to shifts in investor sentiment toward AI and valuations of companies operating in the space.

The latest decline also reflects concerns over founder and CEO Masayoshi Son’s continued conviction in AI’s long-term potential. Son has launched and backed several multibillion-dollar AI initiatives despite uncertain timelines for generating meaningful revenue. He has also dismissed concerns about a potential AI bubble, describing such views as “ignorant”, while leaving SoftBank exposed to significant swings in its market value.

The company is simultaneously taking on additional debt to fund its ambitious expansion. SoftBank plans to raise ¥1 trillion ($6.5 billion) through a retail bond offering and has lined up a $10 billion loan backed by its OpenAI shares.

The fresh financing is being used as SoftBank pursues major investments and acquisitions, including its planned purchases of ABB Robotics and DigitalBridge. The group is also exploring plans to develop data centres across multiple global markets as it seeks to build a broader AI infrastructure ecosystem.

Investor concerns have increased further after Anthropic and OpenAI said in recent days that they would take steps to rein in the development of cutting-edge AI models following a series of troubling security breaches.

Separately, OpenAI co-founder Sam Altman has confirmed that the company does not plan to go public in 2026, removing a potential near-term catalyst for SoftBank and other major investors.

With SoftBank increasingly tied to the AI investment cycle through OpenAI, infrastructure projects, acquisitions and debt-funded bets, investors are now weighing the long-term opportunity in AI against the risks of high valuations, uncertain monetisation timelines and rising financial leverage.