Anthropic's active progress toward a late-2026 listing, including its June confidential SEC filing, September prospectus details, and marketing window targeting mid-October or November, drives the 95.3% market-implied odds it will IPO ahead of OpenAI. The rival has explicitly ruled out a 2026 debut, with CEO Sam Altman citing AI safety and alignment priorities that make public-market scrutiny ill-advised now; OpenAI instead pursues a $30 billion private round at roughly $1.4 trillion valuation. Strong Anthropic revenue growth to a $65–110 billion annualized run rate supports its timeline, yet regulatory reviews, market volatility, or last-minute safety-related pauses could still shift the sequence.