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 has offered a term sheet that would value OpenAI at a pre-money valuation, meaning the valuation without the funding of the current round, at $260 billion.