---
type: NewsArticle
title: "From Leak to Launch: The Full Claude Mythos 5 Story"
description: "How Claude Mythos went from an accidental March leak through Project Glasswing to the public Fable 5 release. The full timeline, dated."
resource: "https://yippy.com/t/aey8r2qm6kth/"
locale: en
published: "2026-06-09T18:39:44.433Z"
timestamp: "2026-06-09T18:39:44.433Z"
tags:
  - "ai"
  - "anthropic"
  - "claude"
  - "claude-fable-5"
  - "cybersecurity"
  - "intelligence-age"
entities:
  - "https://www.anthropic.com"
  - "https://en.wikipedia.org/wiki/Artificial_intelligence"
  - "https://en.wikipedia.org/wiki/Machine_learning"
---

# From Leak to Launch: The Full Claude Mythos 5 Story

A leaked draft, a security program with NATO on the partner list, and an IPO filing: the road to Claude Fable 5 was anything but quiet.

**Contents**

- March 26: the accidental reveal
- April 7: Project Glasswing instead of a launch
- May: the numbers come in
- June: IPO, expansion, release
- Why one model became two

Full text: https://yippy.com/t/aey8r2qm6kth/