Anthropic · Claude · Fable · Mythos

Claude Opus 5.5

Released 22 Sep 2026 · 21 days after Claude Fable 5.1

a new all-time high across the nine labsnotable release

Top of the index. 90 minutes before OpenAI.

Intelligence

59.1

#1 of 21 scored releases to that date

Price

$8.00

per 1M tokens, 3:1 in/out · $4 in / $20 out

Speed

output tokens/s, median

Weights

Closed

US lab

Anthropic’s best score over time