Anthropic’s confidential IPO filing with U.S. regulators in early June 2026 has driven the market-implied 82.5% probability that it will list before OpenAI. The filing, which followed hiring of specialized counsel and recent fundraising at a near-$1 trillion valuation, creates a clear regulatory runway for a potential debut as early as this fall once the SEC review concludes. In contrast, OpenAI continues preparatory work with its bankers and has not yet submitted its own draft prospectus, leaving its timeline more dependent on internal readiness and market conditions. Traders are pricing in Anthropic’s first-mover advantage in the regulatory process while acknowledging that both large language model developers still face typical IPO risks such as valuation shifts or delayed approvals.