SoftBank Group is in talks to lead a funding round of up to $40 billion in artificial intelligence developer OpenAI at a valuation of $300 billion, including the new funds, sources said, in what could be a record single funding round for a private company.

OpenAI is seeking to raise up to $40 billion in new funding at a valuation of $340 billion, the Wall Street Journal reported today.

SoftBank is in talks to invest as much as $25bn into OpenAI, in a deal which would make it the ChatGPT maker’s biggest financial backer, as the pair partner on a massive new artificial intelligence infrastructure project.