Anthropic’s September 22, 2026 announcement of Claude Opus 5.5 explicitly stated that Sonnet 5.5 and Haiku 5.5 would follow “in the coming weeks,” providing the main catalyst for trader sentiment on the next Sonnet release. This confirmation, paired with the lab’s recent cadence—Sonnet 5 shipped June 30 after Sonnet 4.6 in February—has concentrated implied probabilities on late September and early October dates, with September 30 holding the highest share at 28.5%. The broad distribution across nearby days reflects uncertainty over exact timing, as Anthropic rarely pre-announces precise release dates and internal testing or final safety reviews can shift schedules by days. With 90% market-implied odds of a release by October 15, traders appear to view the “coming weeks” window as a reliable near-term signal rather than extended speculation.