Anthropic releases Claude Fable 5.2 and Mythos 5.2: faster, 20% cheaper, Mythos still restricted

Anthropic released two new frontier models on 9 November 2026: Claude Fable 5.2 and Claude Mythos 5.2. According to the company, they are the same underlying model: Fable carries strong cybersecurity and biology safeguards and is open to all users, while Mythos is available only to organizations admitted to Anthropic’s Cyber and Life Sciences Verification Programs.

What is new

• Anthropic says the models improve in coding, reasoning and vision and generate output up to 30% faster than the 5.1 versions.
• Price: $8 per million input tokens and $40 per million output tokens; CNBC reports this is about 20% less than the 5.1 generation. An optional fast mode (up to 2.5× faster generation) costs $16/$80.
• Context window 1 million tokens, maximum output 128,000 tokens (per Anthropic’s docs).
• Fable 5.2 is available on the Claude Platform, Amazon Web Services, Google Cloud and Microsoft Azure/Foundry.

Company claims

Anthropic says that in pre-release testing the models helped complete otherwise infeasible software migrations, designed three working electronic devices, solved two open problems in black-hole physics and formalized the proof of Fermat’s Last Theorem in 30 hours. These are the company’s own claims and have not been independently verified.

Context

CNBC notes this is Anthropic’s first frontier release since CEO Dario Amodei called in September for slowing AI development, and that it comes as the company prepares a possible IPO. Anthropic said the models went through safety and alignment testing with new evaluations and post-launch monitoring.