SAN FRANCISCO, California: Current and former staff at OpenAI are preparing to sell nearly US$6 billion worth of shares in a secondary offering that could lift the company's valuation to $500 billion, a source familiar with the matter told Reuters.

Investors, including SoftBank Group, Thrive Capital, and Dragoneer Investment Group, are in discussions to participate.

The deal, still at an early stage, would mark a sharp jump from OpenAI's current $300 billion valuation and underscores the company's explosive growth and the competition in artificial intelligence to secure talent and capital. Bloomberg News first reported the talks, noting that the final size of the sale could change.

SoftBank, Thrive, and Dragoneer — all existing OpenAI investors — did not respond to requests for comment.

The potential sale comes as SoftBank is already leading OpenAI's $40 billion primary funding round. A secondary offering would provide liquidity to employees while strengthening investor positions in one of the sector's most closely watched firms.

OpenAI, backed by Microsoft, has seen its business accelerate dramatically thanks to its flagship ChatGPT product. The company doubled revenue in the first seven months of the year, hitting an annualized run rate of $12 billion, Reuters reported earlier in August, and is expected to reach $20 billion by year's end.

Its user base has also surged: ChatGPT now has about 700 million weekly active users, up from roughly 400 million in February.