SoftBank Shares Plunge 9.8% as Stargate Project with OpenAI Collapses

SoftBank shares tumbled 9.8% on March 9 — double the broader decline of the Japanese stock market. The selloff was triggered by OpenAI and Oracle scrapping plans to expand their joint data center in Texas under the Stargate initiative, according to the FT.

The $500 Billion Stargate Dream That Never Materialized

Over the past four months, the Japanese tech conglomerate's stock has lost nearly half its value. Growing investor skepticism about SoftBank's massive bet on the makers of ChatGPT is the driving force behind the decline.

In December 2025, the holding company closed a $41 billion investment in OpenAI, bringing its total commitment to $64.6 billion. That same month, media reports highlighted the failure of the high-profile Stargate initiative, which had a planned budget of $500 billion.

The joint venture never assembled a management team, never appointed leadership, and never broke ground on any data centers. For months, the partners failed to agree on fundamental questions:

• Who would build the facilities
• Who would own the completed campuses
• How financing would be allocated among participants

Between September and October 2025, OpenAI executives made multiple trips to Tokyo to negotiate with SoftBank CEO Masayoshi Son. The parties could not reach agreement on the flagship Texas campus. OpenAI explored building it independently, but lenders refused to provide funding.

Why This Matters

The Stargate collapse is more than a corporate setback. The project was positioned as one of the largest AI infrastructure initiatives ever conceived. Its failure raises questions about the AI industry's ability to execute mega-projects requiring coordination between multiple major players. Other companies closely tied to OpenAI are also feeling the pressure, with both Oracle and CoreWeave shares declining.

S&P Downgrades SoftBank's Rating Outlook

Rating agency S&P assigned a negative outlook to SoftBank's already low credit rating. The key concern: an excessive concentration of illiquid assets on the group's balance sheet, accounting for more than half of its $320 billion investment portfolio.

The S&P decision complicates the holding company's efforts to raise debt for further investments in OpenAI. To free up capital for the ChatGPT maker, SoftBank sold $5.8 billion worth of Nvidia shares and a $9.1 billion stake in telecom operator T-Mobile during 2025.

The FT notes that Masayoshi Son has a pattern of becoming overly fixated on a single sector and increasing leverage until he meets resistance from shareholders or creditors. Sometimes this approach pays off — as with the early bet on Alibaba. But there are also cautionary tales, most notably the WeWork debacle.

Beyond OpenAI: Robotics and Infrastructure

SoftBank's ambitions extend beyond OpenAI. The corporation recently spent over $9 billion on robotics and digital infrastructure. In February 2025, SoftBank and OpenAI also agreed to form a joint venture in Japan to deliver AI services to enterprise clients.