Anthropic’s September 28 launch of Claude Sonnet 5.5, positioned as a faster and more efficient upgrade over Sonnet 5 for everyday coding, document creation, and agentic tasks, keeps output token pricing locked at the $10 per million level first introduced with Sonnet 5 in June. That model debuted at an introductory $2/$10 rate per million input/output tokens, later made permanent after the planned September increase was canceled. Traders see limited near-term pressure for a new output price debut on any 5.1+ Sonnet variant because the current rate already undercuts Opus-tier models while delivering competitive agentic performance. Key upcoming catalysts include potential Sonnet 5.1 or Haiku 5.5 releases and any API or platform pricing adjustments announced alongside them.