OpenAI has confidentially filed for a US initial public offering.

The generative AI company did not disclose the size or terms of the offering.

"We recently submitted a confidential S-1," OpenAI said in a statement.

"We expect it to leak so we’re just announcing it. We have not decided on timing yet; it may be a while because there are things we want to do that are likely easier as a private company. But it’s a complicated set of tradeoffs and this gives us the option to go public sooner if that ends up being best."

Reuters last year reported that the company is targeting a valuation of up to $1 trillion in an IPO as early as September, but the company's plans may have changed.

The filing announcement comes a week after rival Anthropic also filed for an IPO.

Anthropic was valued at $965 billion in a May fundraise, more than OpenAI's $852bn valuation in March.