Moonshot AI released Kimi K3.1 Pro on October 23, 2026, a post-trained MoE model with 2.8T total parameters, 1M-token context, and multimodal capabilities, positioning it as a strong open-weight contender. It quickly ranked #8 in Code Arena: WebDev and #11 in Agent Arena, matching or approaching Claude Opus 5.5 on agentic coding benchmarks like Terminal-Bench 4.0 while offering substantially lower API pricing. The model’s gains stem from expanded joint RL across domains, and open weights are scheduled for November 4. Traders are watching for its entry into the main Text Arena leaderboard, where prior Kimi variants have performed well, alongside any independent evaluations that could shift sentiment before the weights drop.