On the day it was announced that Japanese telco SoftBank sold its entire stake in U.S. chip designer Nvidia for $5.83 billion, the company also reported that it sold more of its shares in T-Mobile US.

In its consolidated financial report for the six months to September 30, 2025, SoftBank confirmed it sold 40.2 million shares of T-Mobile for $9.17 billion.

According to SoftBank, these shares were sold during the three months from June up until September.

The company has moved to offload some of its stakes in other businesses to make good on its previous commitment to invest in ChatGPT maker OpenAI.

“We want to provide a lot of investment opportunities for investors, while we can still maintain financial strength,” said Yoshimitsu Goto, chief financial officer, SoftBank, during an investor presentation, as reported by CNBC.

Goto added that the stake sales are part of the firm's strategy for “asset monetization.”

The sale of some of its T-Mobile stake is the second time SoftBank has sold shares in T-Mobile this year.

In June, the company sold around a quarter of its T-Mobile US stake for $4.8 billion. At that point, SoftBank had a stake of 7.52%.

SoftBank remains the second-largest shareholder in T-Mobile US, behind the carrier's parent company, Deutsche Telekom. DT holds a majority stake of just over 50% in the carrier.

Early last year, SoftBank told T-Mobile to issue 48.75 million shares in common stock to it after conditions set out in an agreement made as part of the merger of SoftBank's US telco, Sprint, and T-Mobile were met.

SoftBank has been splashing out on AI investments this year, and said in April it would put $30 billion into OpenAI.

Both OpenAI and SoftBank are backers of Stargate, a purported $500 billion effort to build AI data centers for training and inference.

The pair is reportedly each expected to invest $19 billion in Stargate - although OpenAI's investment will likely come from the funds raised in this round from SoftBank.