OpenAI Files for IPO, Setting Up a Showdown with Rival Anthropic

OpenAI confidentially filed for an initial public offering (IPO), setting it up for a potential showdown with rival Anthropic, which filed for its own IPO last week. OpenAI's filing comes after a post-money valuation of $852 billion in March.

OpenAI has confidentially filed a draft S-1 with the SEC, joining the largest cohort of AI listings in market history and setting up a direct showdown with rival Anthropic, which filed its own paperwork roughly a week earlier . OpenAI was last valued at $852 billion post-money in its March 2026 funding round, while Anthropic filed at a $965 billion valuation .

Reports place Goldman Sachs and Morgan Stanley on the deal, with a potential debut as soon as September 2026 at a valuation in the $730 billion to $850 billion range. The two filings anchor an AI IPO pipeline now estimated at roughly $3.6 trillion, the most concentrated wave of mega-cap tech listings the public markets have seen. OpenAI cautioned that timing is not set, noting there are 'things we want to do that are likely easier as a private company'.

The filing matters beyond OpenAI: an S-1 forces the company to disclose actual revenue and margins for the first time, a direct test of valuations that have far outrun reported financials. Investors in AI-exposed names from NVDA to MSFT could see sentiment swing on what those numbers reveal.