Anthropic’s Claude Fable 5.1 launch on September 1, 2026, established the current baseline, with leaks from September pointing to a 5.2 or higher successor via new pretraining runs expected in late September or early October. No official announcement, model card, or public API identifier has appeared yet, keeping the qualifying release—defined as any Fable 5.2+ made generally available via open beta or waitlist—on hold as of October 11. Trader consensus on Polymarket reflects this cadence, pricing a 71% implied probability by October 31 and 96% by year-end while assigning only 25-33% odds to this week, driven by the three-month gap between prior Fable versions and ongoing competitive pressure from models like GPT-5.5 and open-weight alternatives. Key near-term catalysts include potential Anthropic earnings commentary or developer conference updates that could confirm timelines or slip them due to safety reviews.