**Anthropic released Claude Sonnet 5 on June 30, 2026, as its most agentic mid-tier model yet, with output token pricing debuting at $10 per million tokens (introductory $2/$10 input/output rates made permanent by early September).** This positions it close to Opus 4.8 performance on agentic coding and tool-use benchmarks like SWE-bench and OSWorld while costing roughly half as much, driving adoption as the default on Free/Pro plans and a scalable option for developers. Newer releases such as Opus 5.5 ($4/$20) and Fable 5.1 ($10/$50) in September have not included a Sonnet 5.1 update, leaving Sonnet 5’s $10/MTok output rate as the current benchmark. Traders are watching for any 5.1+ Sonnet debut that could introduce efficiency gains, a revised tokenizer impact, or pricing shifts amid competition from OpenAI and Google models, with Anthropic’s release cadence and API availability on Bedrock and Vertex AI as key near-term signals.