ChatGPT maker OpenAI confidentially filed for a U.S. initial public offering recently, the company said on Monday, joining rival Anthropic in ​a push toward the stock market as investors seek exposure to the artificial intelligence boom.

OpenAI did not disclose the size or terms of the offering, and 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.