Artificial Analysis updates the leading SI ranking: Claude Fable 5.1 first, GPT-6 Astra second
Prepared by Sintelligent with the help of SI. Publication time restored from the build log. . Updated: .
Models "eat up" tests so fast that the yardsticks have to be redone on the fly, and on the new, tougher scale the leaders are still neck and neck.
In version Intelligence Index v4.2, Claude Fable 5.1 scored 57 points and GPT-6 Astra 55 (4 points more than its predecessor GPT-5.6 Sol), with Meta the third lab. The "saturated" scientific reasoning test GPQA Diamond was removed from the index, and AA-Briefcase (multi-week agentic projects with thousands of files) and GDP.pdf (reasoning over 4,592 pages of documents) were added. The share of held-out test sets that cannot be "memorized" rose from 20% to 40%; meanwhile Astra uses fewer tokens per task than almost any model at the frontier.
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