Japanese technology investor SoftBank is reportedly in discussions to invest up to $25 billion in artificial intelligence company OpenAI, in a deal that would make it the ChatGPT maker's largest financial backer, surpassing current leading shareholder Microsoft.

The potential investment comes as the two companies strengthen their partnership following last week's announcement of Stargate, an ambitious $100 billion data centre project that could expand to $500 billion over four years.

"The talks are ongoing and the amount that SoftBank could invest in primary equity into OpenAI is a moving target," one source told the Financial Times.

The deal would see SoftBank invest between $15-25 billion directly into OpenAI, in addition to its existing $15 billion commitment to the Stargate project. The Japanese firm's total investment could exceed $40 billion, marking one of its largest-ever investments and dwarfing its previous $16 billion investment in WeWork.

The investment plans reflect SoftBank founder Masayoshi Son's strategic push to become a leading force in artificial intelligence development. Son has been actively pursuing OpenAI chief executive officer Sam Altman, viewing a larger stake in the company as crucial to his vision of advancing 'superintelligence' - technology that surpasses human cognitive abilities.

OpenAI, which reached a $157 billion valuation in 2024, has been exploring ways to reduce its dependence on Microsoft for computing resources. The Stargate agreement has already led to Microsoft relinquishing its position as OpenAI's exclusive cloud service provider.

The investment discussions have received support from senior executives and the board at OpenAI. SoftBank previously acquired a $2 billion stake in OpenAI last year, while Microsoft has invested approximately $13 billion since 2019.

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