Theft or leak of a frontier lab's model weights is publicly confirmed
The index says: very unlikely (10%). Graded on that date, right or wrong, in public.
Why the index thinks so
Labs report heavier state-level targeting and outsiders reached the withheld Mythos Preview through a vendor, but no confirmed frontier-weight theft has been disclosed to date.
What would move it
Government attribution statements; lab security incident disclosures.