Background: On 12 June 2026 the US ordered Anthropic to block all foreign nationals — including its own foreign-national employees — from Fable 5 and Mythos 5. Anthropic's London office is staffed mostly by non-US-persons, so a durable export regime could push Anthropic to shrink or relocate London work (especially frontier-model and model-facing engineering). This market asks whether that actually happens.

Resolves YES if either of the following occurs before the resolution date:
(a) Anthropic's London-based headcount falls ≥25% below its baseline (the count on the primary source as of this market's creation), at any measured point; or
(b) Anthropic publicly announces closure of its London office, or a reduction of its London workforce or leased London office space of ≥25%.
Otherwise resolves NO.