Anthropic’s June 30 release of Claude Sonnet 5 established a $10 per million output token price that was later made permanent after an initial $2/$10 introductory rate, positioning the model as a cost-effective agentic option close to Opus 4.8 performance. Recent September 2026 launches, including Opus 5.5 at $20 per million output and Fable 5.1 at $50 per million, highlight Anthropic’s tiered pricing that scales with capability while favoring lower rates for Sonnet-class models. Traders are watching for any Sonnet 5.1 announcement, as competitive pressure from OpenAI and Google models, plus historical patterns of mid-tier releases retaining or slightly adjusting Sonnet pricing, could influence debut output token costs amid ongoing focus on agentic benchmarks and developer adoption.