Anthropic’s explicit confirmation in the September 22 Opus 5.5 launch post that Sonnet 5.5 and Haiku 5.5 would arrive “in the coming weeks” has anchored trader expectations around the immediate term, with the market pricing September 28–29 as the clear frontrunners at a combined 92% implied probability. This follows the rapid cadence of 2026 releases—Sonnet 5 in June, Opus 5.5 just days ago—and unconfirmed community reports of stealth testing for the next Sonnet variant. The tight clustering on the next two days reflects both historical release timing and the absence of any announced delay, while the modest probability assigned to early October captures residual execution or announcement risk typical in large language model launches.