Report: Anthropic denied UK AI Security Institute pre-release access to 'Mythos 5.1', a first

ccerrato147 · x · 2026-09-21

Per this thread citing an FT report (Sep 9): Anthropic declined to give the UK AI Security Institute pre-release access to 'Mythos 5.1' — the first time a major model was withheld from the institute before launch.

Access reportedly remains limited to vetted US organisations, with no public reason given. Note: the model and event are unverified; treat with caution.

Related event: Anthropic denies UK AI Safety Institute pre-release access to new model(3 posts)→

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