Anthropic's public S-1 filing on October 26, 2026, with a planned Nasdaq listing under ticker ANT in mid-November, has driven near-certain market-implied odds that it will reach public markets ahead of OpenAI. The Claude developer reported $16.3 billion in first-half 2026 revenue alongside its first quarterly operating profit, positioning the IPO as a major test of AI sector valuations. OpenAI, by contrast, has explicitly deferred any 2026 debut, with CEO Sam Altman citing AI safety and alignment priorities, and is instead accelerating a private round targeting over $1.4 trillion valuation. Traders see limited realistic paths for reversal, though last-minute regulatory scrutiny, roadshow delays, or sudden shifts in OpenAI's timeline remain possible given the fast-moving large language model landscape.