Anthropic’s established quarterly release cadence for the Claude Fable series drives the current market-implied odds, with Fable 5.1 launching September 1, 2026, following Fable 5 in June. Traders price a median release around November 13, 2026, reflecting 72% implied probability by November 19 and 97% by December 31, as the model remains in testing with demonstrated strengths in coding, game generation, and interactive JavaScript scenes from single prompts. Competitive pressure from models like GPT-6 Astra and ongoing internal progress on agentic capabilities add support, though no official announcement has confirmed an exact timeline. Key upcoming catalysts include potential API updates or developer conference reveals that could accelerate or delay resolution.