Anthropic's Opus 5.5 Matches Fable Performance at 40% Lower Cost

Anthropic released Claude Opus 5.5 on September 22, 2026, a new mid-tier flagship that delivers Fable-class performance while reducing costs by approximately 40% compared to its predecessor, creating a significant value realignment across the company's model lineup. The new model arrives just two months after Opus 5's July launch and represents the first Opus to outperform Fable 5.1—released just three weeks prior on September 1—on multiple professional benchmarks, marking a major competitive shift within Anthropic's own catalog.