Moonshot AI released Kimi K3.1 Pro on October 23, 2026, as a post-trained 2.8T MoE model with 104B active parameters and a 1M-token context window. It quickly posted strong results on specialized leaderboards, reaching #8 in Code Arena: WebDev (matching Claude Opus 5.5 Max at far lower cost) and #11 in Agent Arena, with gains in coding and agentic tasks over its predecessor Kimi K3. The model has yet to appear on the main Text Arena leaderboard, where Kimi K3 currently ranks around 16th. Traders are focused on the scheduled full open-weights release by November 4, which historically drives rapid community submissions, blind human evaluations, and Elo accumulation that could determine its debut rank and trajectory through mid-2027.