The ex-dividend date, also known as the reinvestment date, is an investment term involving the timing of payment of dividends on stocks of corporations, income trusts, and other financial holdings, both publicly and privately held. The ex-date or ex-dividend date represents the date on or after which a security is traded without a previously declared dividend or distribution. Usually, but not necessarily, the opening price is the last closing price less the dividend amount.

A person purchasing a stock before its ex-dividend date, and holding the position before the market opens on the ex-dividend date, is entitled to the dividend. A person purchasing a stock on its ex-dividend date or after will not receive the current dividend payment.

To determine the ultimate eligibility of a dividend or distribution, the record date, not the ex-date, is relevant. Each shareholder entered in the shareholders' register at the record date is entitled to a dividend. Usually, the person owning the stock at the end of the trading day one business day before the ex-date is also the person registered in the shareholders register on the record date, because companies set the ex-date and record date of the dividend in line with the settlement cycle of the security. Most developed financial markets such as the USA, UK, Germany, France, etc. use a settlement cycle of T+2 for stocks. As a result, companies in these markets set the ex-date one day before the record date of the dividend (example: ex-date Wednesday, record date Thursday: a security purchased on Tuesday will settle on Thursday; a person who bought the security on Tuesday bought one day before the ex-date and will be registered as shareholder on Thursday and hence be entitled to the dividend).