On March 9th, SoftBank shares plummeted by 9.8%, doubling the overall decline of the Japanese stock market. The cause was the cancellation of plans by OpenAI and Oracle to expand their joint data center in Texas under the Stargate initiative, reports the FT.
Over four months, the Japanese giant’s shares have nearly halved in value. This trend is linked to growing investor skepticism about SoftBank’s investment in the creators of ChatGPT.
In December 2025, SoftBank completed a deal to invest $41 billion in AI startup OpenAI, raising its total investment to $64.6 billion.
That same month, media highlighted the failure of the much-publicized Stargate initiative, which was supposed to receive a $500 billion investment. The joint venture failed to form a team, appoint leadership, or begin constructing data centers. For months, partners could not agree on basic issues: who would build the facilities, who would own them, and how funding would be allocated.
From September to October 2025, top executives of the AI startup made several trips to Tokyo for negotiations with SoftBank’s head, Masayoshi Son. However, the parties could not decide who would be the developer and owner of the flagship campus in Texas.
OpenAI considered implementing the project independently, but creditors refused to provide funding.
Rating Downgrade
S&P assigned a negative outlook to SoftBank’s already low rating. The reason was the excessively large volume of illiquid assets on the group’s balance sheet, which account for more than half of its $320 billion investment portfolio.
S&P’s decision complicates the holding’s attempts to secure loans for further investments in OpenAI. To free up capital for the creator of ChatGPT, SoftBank sold part of its Nvidia shares for $5.8 billion and a stake in T-Mobile for $9.1 billion in 2025.
The FT noted that Son often becomes overly enthusiastic about a single sector and increases leverage until he encounters resistance from shareholders or creditors.
Sometimes this pays off. For instance, SoftBank made an early bet on Alibaba. However, there are also unsuccessful examples like the collapse of WeWork.
Other companies closely tied to OpenAI are also under pressure: shares of Oracle and CoreWeave are also declining.
SoftBank’s interests are not limited to the developer of ChatGPT. Recently, the corporation spent over $9 billion on robotics and digital infrastructure.
In February 2025, SoftBank and OpenAI agreed to establish a joint venture in Japan to provide AI services to corporate clients.