OpenAI did not disclose the size or terms of the offering, and said a timeline has not yet been determined.

ChatGPT-maker OpenAI has confidentially filed for a United States initial public offering (IPO), joining rival Anthropic in a push towards the stock market as investors seek exposure to the artificial intelligence boom.

OpenAI did not disclose the size or terms of the offering. It said a timeline has not yet been determined. “It may be a while because there are things we want to do that are likely easier as a private company,” it said in a statement on Monday.

The Reuters news agency previously reported that the AI giant is targeting a valuation of up to $1 trillion in a stock market debut that could come as early as September.

At that valuation, OpenAI would set the stage for a trio of trillion-dollar valuation companies debuting rapidly, seen as the most consequential test of investor appetite for high-growth technology stocks in the recent decade.

Elon Musk’s SpaceX was the first off the block, filing for an IPO that would rank as the largest in history if completed, with the company pursuing a $75bn offering at a $1.75 trillion valuation.

The AI era

The IPOs from Anthropic and OpenAI would crystallise a transformative period for the technology industry and global markets, with AI rapidly emerging as the defining investment theme of the decade.

OpenAI said earlier this year that it was raising $110bn at an $840bn valuation from a roster of heavyweight backers, including SoftBank, Amazon and Nvidia.

At the time, it also disclosed that ChatGPT had more than 900 million weekly active users and more than 50 million consumer subscribers.

The IPO filing follows OpenAI renegotiating its partnership with Microsoft, one of its earliest investors, which allowed the AI pioneer to forge new partnerships with firms such as Amazon.com and Alphabet’s Google unit.

The Windows maker’s early investment, totalling $13 billion since 2019, helped pave the way for OpenAI’s rapid rise and powered growth at ‌the software ⁠major’s Azure cloud-computing business.

In March, OpenAI said it was generating $2bn in monthly revenue and growing roughly four times faster than companies that defined the internet and mobile eras, including Alphabet and Meta.

That compares with about $1bn in quarterly revenue at the end of 2024.

Altman vs Musk

OpenAI was founded in 2015 as a research-focused nonprofit, but created a for-profit arm four years later to help fund the soaring costs of developing artificial intelligence systems.

Its unusual structure, which gave the nonprofit control over the for-profit entity, came under intense scrutiny in late 2023, when CEO Sam Altman was briefly ousted before returning days later after employees revolted.

In December 2024, OpenAI unveiled plans to overhaul its structure by creating a public benefit corporation, saying the move would help it raise far more capital while easing restrictions imposed by its nonprofit parent.

OpenAI’s overhaul quickly became controversial after sharp criticism from its early backer, billionaire Musk, who later sued OpenAI and accused Altman and other executives of turning the nonprofit into a vehicle for private enrichment.

A US jury in May ruled against Musk in his lawsuit, finding the AI company not liable to the world’s richest person for having allegedly strayed from its original mission to benefit humanity.

The unanimous verdict removed a key overhang on the IPO, with analysts saying it cleared a major legal hurdle that public market investors are often wary of.