Anthropic’s September 22 release of Claude Opus 5.5 at $20 per million output tokens—down 20% from Opus 5’s $25 rate—sets the immediate precedent for the 5.x Opus series. The model delivers Fable 5.1-level performance on coding and knowledge-work benchmarks at roughly 40% lower run cost, with cache reads also cut sharply, reflecting Anthropic’s emphasis on efficiency and “pacing the frontier” after CEO Dario Amodei’s recent alignment comments. External safety reviews by METR and Frontier Design accompanied the launch, while Sonnet 5.5 and Haiku 5.5 are slated for the coming weeks. Traders appear focused on whether this downward pricing trajectory continues for any Opus 5.6 or later debut, given the rapid iteration cycle and competitive pressure to deliver capable agents at lower token costs.