Methodology & Sources
Index membership
Index membership is verified against the authoritative source: the index provider's own announcements (S&P Dow Jones Indices, Nasdaq), official exchange tables (LSE, NSE), or — where no official list is published — a maintained public list. Every refresh is validated before it goes live: a member count out of range, or more than 20% of members changing at once, keeps the last good version. An automated weekly check flags any difference against third-party aggregators for human review.
Corrections
Every manual correction to a constituent list is dated in our corrections log, with the reason (delisting, rename, demotion, etc.).
Market caps & currency
Market caps come from Yahoo Finance for each company's home listing (TSX listings in CAD, LSE in GBP, and so on). Non-USD indices can be viewed in native currency or converted to USD at that day's FX rate; the rate and date are shown.
HQ locations
Headquarters cities come from company filings via Yahoo Finance and are geocoded with OpenStreetMap's Nominatim. A handful of investment trusts with no city in filings carry manually verified locations.
CEOs & pay
CEO identity cross-checks Wikidata against Yahoo Finance officer data; disagreements are flagged for manual review. Pay figures come from proxy filings via Yahoo Finance and are attributed to the person who earned them, not necessarily the current CEO.