AI BriefingKimi K3.1 Pro narrows open-source gap to best closed model to 31 days
·2026.10.23 09:00
Key point
Kimi K3.1 Pro scores 55.1 on the Artificial Analysis Intelligence Index, placing open-source AI just 31 days behind the best closed model, Claude Opus 5.5.
Details
- Kimi released K3.1 Pro on 23 Oct 2026, scoring 55.1 on the Artificial Analysis Intelligence Index, which is 2.5 points below the top model, Claude Opus 5.5 (57.6).
- The gap between the best open-source and closed models has shrunk to 31 days, down from 104 days when Xiaomi released MiMo-V2.6-Pro in September.
- Kimi K3.1 Pro matches the pricing of Claude Sonnet 5.5 at $2 per million input tokens and $10 per million output tokens, with weights scheduled for free download by 4 Nov 2026.
- Chinese labs have held the top open-source model position for 765 consecutive days since 19 Sep 2024, with six different Chinese labs leading at various points.
- Meta's recent release, Muse Spark Open, scores 38.9, making it the best open model from outside China but still 91 days behind the Chinese lead at the time of its release.
- The median lag for non-Chinese open models was 109 days in 2025 and 145.5 days in 2026, though Meta's release has reduced the gap between non-Chinese and Chinese open models to approximately three months.
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