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FrontierThe story, in brief

Anthropic Releases Claude Opus 5.5: Fable 5.1-Level Performance at 40% Lower Running Cost Than Opus 5

Anthropic ships Claude Opus 5.5: Fable 5.1-level performance at 40% lower cost. The efficiency play is reshaping frontier model economics.

Reporting by MarkTechPost 1 min brief
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The KeyNews take

Why it matters

A major frontier lab releases a new model tier that matches prior-generation capability at significantly reduced inference cost—a shift in how labs compete on capability-per-dollar, not just raw performance. Practitioners budgeting Claude workloads will recalculate; enthusiasts tracking the lab race see a new efficiency-first competitive move.

The key facts

5 to know

  1. Claude Opus 5.5 released as first model in Claude 5.5 family

  2. Performance matches Claude Fable 5.1 on most workloads

  3. 40% lower running cost than Opus 5 at default settings

  4. Leads on agentic coding benchmarks (per Anthropic's internal evals)

  5. Published Sep 22, 2026

Go to the source

MarkTechPostmarktechpost.com

Publisher excerpt: Anthropic has released Claude Opus 5.5, the first model in its new Claude 5.5 family. The team states it performs at the level of Claude Fable 5.1 on most work. It also costs 40% less to run than Opus 5 on typical workloads at default settings. On Anthropic’s own benchmarks, it leads in agentic…
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