By the end of 9 October 2026 neither the AI Security Institute blog nor gov.uk published any statement that AISI had access to Anthropic's Mythos 5.1; the latest AISI post on Mythos is its April 2026 evaluation of Mythos Preview.
The testing market resolves YES if the AI Security Institute or a UK minister confirms in a published statement by 9 October that AISI has been given access to Anthropic's Mythos 5.1, on aisi.gov.uk or gov.uk. An Anthropic announcement of an intention to submit the model does not settle it; if nothing official is published, the Financial Times and the Times reports of the position on that date decide.
We found eight public warnings since March 2023. In each, staff or leaders at a leading AI lab said their own technology could cause a disaster or end humanity. We then checked whether, within 30 days, the UK government or Parliament, or the US federal government, took a formal step to hold back the building or release of the most powerful models.