The first day of trading when the seller, rather than the buyer, of a stock will be entitled to the most recently announced dividend payment. This date set by the NYSE (and generally followed on other US exchanges) is currently two business days before the record date. A stock that has gone ex-dividend is marked with an x in newspaper listings on that date. The New York Times Financial Glossary
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ex-dividend date UK US noun [C] FINANCE
► the date before which an investor must buy a share in order to have the right to receive a particular dividend (= payment): »
If an investor does not own the stock before the ex-dividend date, he or she will be ineligible for the dividend payout.
Financial and business terms. 2012.