Jan 30 (Reuters) - SoftBank is in talks to lead a

funding round of up to $40 billion in OpenAI at a post-money

valuation of $300 billion, sources told Reuters, in what could

be the largest ever single funding round for a private company.

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. This marks a jump for the

ChatGPT maker from a few months ago, when it was last valued at

$150 billion, added the sources, who requested anonymity to

discuss private matters.

OpenAI and SoftBank declined to comment. The Wall Street

Journal reported earlier on Thursday that OpenAI was in talks

with SoftBank for an investment round to raise nearly $40

billion that would value the AI startup at up to $340 billion.

SoftBank could invest $15 billion to $25 billion

directly into Microsoft ( MSFT )-backed OpenAI, some of which

may be used to pay for OpenAI's commitment to Stargate, one of

the sources added.

Stargate, a joint venture by Oracle, OpenAI and

SoftBank, plans to invest up to $500 billion to help the U.S.

stay ahead of China and other rivals in the global AI race.

SoftBank's investment would be on top of the $15 billion it

has already committed to Stargate, the person said, adding the

talks are at an early stage.