Anthropic has maintained Claude Fable models at a premium $10/$50 per million input/output token price since Fable 5 launched in June 2026 and carried over to the September 1 Fable 5.1 update, positioning the Mythos-class tier well above Opus 5.5 ($4/$20) and Sonnet 5.5 ($2/$10). Leaks from early September referenced a new pretraining run potentially targeting late September or early October, yet Anthropic instead shipped the 5.5 Opus/Sonnet/Haiku lineup without advancing the Fable line. Trader focus centers on whether competitive pressure from OpenAI’s GPT-6-class models and the company’s IPO timeline will prompt a price adjustment on debut or preserve the $50 output rate to signal frontier capability. No official confirmation of Fable 5.2+ exists as of early October, leaving resolution dependent on the next Anthropic model announcement.