# 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

> Fable 5 ships to everyone today; Mythos 5 stays gated to Glasswing partners and biology researchers.

- Org: Anthropic
- Date: 2026-06-09
- Category: model
- Source: https://www.anthropic.com/news/claude-fable-5-mythos-5
- Canonical page: https://ai-tldr.dev/releases/anthropic-claude-fable-5-mythos-5/

## In short

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.

## What it is

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 it works

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 it matters

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 it's 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

## Links

- [Announcement](https://www.anthropic.com/news/claude-fable-5-mythos-5)
- [System Card](https://www.anthropic.com/claude-fable-5-mythos-5-system-card)
- [Claude Models Docs](https://platform.claude.com/docs/en/about-claude/models/overview)
- [Project Glasswing](https://www.anthropic.com/glasswing)
- [HN Discussion](https://news.ycombinator.com/item?id=48463808)