Anthropic’s accelerated IPO preparations, including a June 2026 confidential S-1 filing and recent reports targeting mid-October marketing with a potential November listing at up to $2 trillion, drive the 96.4% market-implied odds that it reaches public markets ahead of OpenAI. The company’s revenue trajectory, large-scale funding, and underwriting support from major banks have positioned it for a late-2026 debut, while OpenAI’s own confidential filing has been followed by internal signals favoring a 2027 timeline amid valuation targets near $1 trillion and market caution. Traders assign low probability to reversal because OpenAI’s leadership has prioritized private flexibility and infrastructure commitments over an immediate listing. Still, shifts could occur if Anthropic encounters regulatory delays, credit facility complications, or adverse market conditions that push its schedule into 2027, or if OpenAI accelerates its process on improved sentiment.