Anthropic’s confidential SEC filing in June 2026 and active preparation for a November listing, including recent prospectus details showing surging revenue run rates above $65 billion, have cemented trader consensus around its first-mover status. OpenAI, by contrast, has repeatedly signaled it will not pursue an IPO in 2026, with CEO Sam Altman citing the need to prioritize AI safety, alignment work, and regulatory coordination before facing public-market scrutiny. This divergence in timelines—Anthropic targeting pre-Thanksgiving trading versus OpenAI shifting focus to 2027 and fresh private rounds—drives the 95.9% implied probability. Remaining uncertainty stems from potential last-minute regulatory delays, market volatility affecting Anthropic’s roadshow, or an unforeseen shift in OpenAI’s safety timeline that could compress or extend its path to public markets.