Opus 5.5 Delivers Fable-Class Performance at 40% Lower Cost, Achieves New Agentic Benchmark Records

Anthropic released Claude Opus 5.5 on September 22, 2026, establishing itself as the company's most cost-efficient frontier model while matching or exceeding Fable 5.1 performance on key benchmarks. The new model delivers 40% cost reduction compared to Opus 5 and executes 30% faster, with execution speeds up to 2.5x quicker than its predecessor.