OpenAI has filed confidentially with US regulators for an initial public offering at an undisclosed date, following on from rival Anthropic days earlier.

The company said in a statement that it has not yet decided on an IPO date as “there are things we want to do that are likely easier as a private company”.

“This gives us the option to go public sooner if that ends up being best,” the start-up said.

Reports have suggested OpenAI may seek to enter public markets this autumn.

Listing on public markets would allow OpenAI to bring in funds from a wider range of investors, at a time when the loss-making start-up is spending heavily on resources such as data centres to power its services.

The company was valued at $852 billion (£640bn) in its most recent funding round.

The filing comes weeks after a jury thew out a case against OpenAI by Elon Musk, who contributed several million to the firm in the form of charitable donations, before the creation of its for-profit subsidiary.

That case could have threatened OpenAI’s IPO plans.

Musk’s SpaceX, which has an AI business acquired from start-up xAI, is also planning a public offering in the coming weeks.

The IPOs of Anthropic, OpenAI and SpaceX are all expected to value the companies at $1tn or greater.

A confidential filing allows firms to negotiate issues privately with regulators before approaching the public.