Doubling its valuation would be unprecedented in Silicon Valley history and signals the vast sums needed to build world-leading AI models from scratch, much of it on cutting-edge computing and infrastructure.
SoftBank and OpenAI are part of the Stargate drive announced by US President Donald Trump to invest up to US$500b in artificial intelligence infrastructure in the United States.
The new funds would partly go to help OpenAI fulfil its roughly US$18b commitment to Stargate, the Journal said.
The Japanese firm’s mooted investment would come on top of its commitment of more than US$15b to Stargate, the FT said, citing people with direct knowledge of the negotiations.
“Ultimately, the Japanese company could spend more than US$40b on its partnership with OpenAI,” the report said.
SoftBank was not immediately available for comment. OpenAI did not immediately respond to a request for comment.
Shares in Softbank rose 3% in Tokyo trading on Thursday.
The company, founded by Japanese tycoon Masayoshi Son, made spectacularly successful early bets on Yahoo! and Alibaba in the 1990s, but some of its other investments have bombed.
Securing huge funding from Saudi Arabia, Abu Dhabi and others, Son – an early backer of Trump – has sought to pivot into AI, helped by SoftBank’s stake in chip designer Arm.
Elon Musk has openly poured scorn on Stargate, saying on X this month the main investors “don’t actually have the money”.
The world’s richest man was an early investor in OpenAI and has long been in a feud with its founder Sam Altman, who called the Tesla founder’s comments “wrong”.
– Agence France-Presse
