Artificial Analysis Index v5 puts Claude Opus 5.5 first at 58, GPT-6 Astra at 57
Artificial Analysis launched Intelligence Index v5, its composite score of model ability, with 60% now based on private test sets or held-out answers so models can't train on the test. Claude Opus 5.5 leads at 58, ahead of GPT-6 Astra at 57 and GPT-6.1 Sol at 55. The gap between open-weights and closed models widened from 3 points to 12, and cost per task varies by more than 13x among the leading models.