What the research says
The academic record is genuinely mixed, which is exactly why this ledger exists. The best-known study, Ni, Pearson and Poteshman’s “Stock price clustering on option expiration dates” (Journal of Financial Economics, 2005), documented that optionable stocks cluster near strike prices on expiration Fridays more than chance allows, consistent with hedging pressure — but clustering near a strike is a weaker claim than settling at the max painstrike, and later work disputes whether a tradable edge survives costs. We cite the literature and then do the thing the literature can’t: measure our own published numbers, in public, on this page.
Method, exactly
Snapshots run each weekday evening after the close, from Cboe’s delayed public feed. A settlement is counted only when we hold both sides of it: a max pain reading taken on or before expiration day, and the expiration-day snapshot supplying the closing price. If we missed a day, that expiration is skipped — gaps are gaps, not estimates. “Settle” here is the delayed close, not the official OCC settlement value, which can differ slightly for AM-settled index options. Educational information, not investment advice.