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Mythos 5.1
● liveLive - shipped Sep 1 with Fable 5.1; verified organizations only: life-science teams through the Life Sciences Verification Program (Sep 17), security teams through the three-tier Cyber Verification Program (Oct 6). On the board as live since 2026-09-01 — the watchers keep tracking it: lineup changes, pricing moves and deprecations all alert.
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Timeline
Anthropic has expanded its Cyber Verification Program (CVP) into three access tiers that give verified security professionals reduced cyber safeguards on Claude Opus 5.5, Claude Sonnet 5.5 and Claude Mythos 5.1, plus new models as they ship.
The official word
We alert on verified API behavior, never on announcements alone — but when Anthropic speaks, it's here: anthropic.com/news ↗
Mythos 5.1: quick answers
Is Mythos 5.1 out?
Yes. Mythos 5.1 is live and has been since September 1, 2026.
When was Mythos 5.1 released?
September 1, 2026.
Who makes Mythos 5.1?
Anthropic. ArtificialWatch also tracks Claude Haiku 5.5, Claude Sonnet 5.5, Claude Opus 5.5, Fable 5.1, Claude Opus 5, Fable 5, Claude Sonnet 5 and Mythos 5 from Anthropic.
More from Anthropic
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<a href="https://artificialwatch.com/model/mythos-5-1">Mythos 5.1 on ArtificialWatch</a>ArtificialWatch, "Mythos 5.1", https://artificialwatch.com/model/mythos-5-1Know when Anthropic's next model drops. Free.
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