Anthropic · 2026-06-09 · seismic
Anthropic Ships Claude Fable 5 and Claude Mythos 5 — New Flagship Tops Hebbia's Finance Benchmark and Cognition's FrontierCode Eval at $10/$50 per Million Tokens, With Mythos 5 Restricted to Project Glasswing Partners and Select Biology Researchers
Anthropic's next-gen flagship lands as two checkpoints from the same training run: Fable 5 with safeguards for general use, Mythos 5 with safeguards lifted for authorized cyber and biology partners.
Fable 5 ships to everyone today; Mythos 5 stays gated to Glasswing partners and biology researchers.
Key specs
| Price (input) | $10 |
|---|---|
| Price (output) | $50 |
| Hn points | 1,593 |
What is it?
Anthropic's next generation of Claude, released as two products built on the same underlying model. Fable 5 is the public model on the Claude API and consumer apps. Mythos 5 is the same training run with safeguards lifted, restricted to vetted cyber-defense partners in Project Glasswing and a handful of biology researchers.
How does it work?
One pretraining run, two product configurations. Fable 5 keeps the constitutional classifiers, refusal training, and silent-degradation safeguards Anthropic uses for general release. Mythos 5 strips those safeguards for authorized users running zero-day discovery and protein-design work. The 319-page system card documents both, including a path Anthropic calls 'silent performance degradation' for some frontier AI development tasks.
Why does it matter?
Fable 5 doubles Opus 4.8 pricing to $10/$50 per million tokens but Anthropic claims state-of-the-art on nearly every internal benchmark, including Hebbia's Finance Benchmark and Cognition's FrontierCode coding eval. Mythos 5 is the next step in Anthropic's restricted-access pattern, putting frontier dual-use capability behind a partner program rather than a general API.
Who is it for?
Claude API users, Enterprise customers, Project Glasswing partners
Try it
Available now on the Claude API; rolling out to Pro and Max subscribers through June 22