Ex-dividend date

http://www.sec.gov/answers/dividen.htm

Once the company sets the record date, the stock exchanges or the National Association of Securities Dealers, Inc. fix the ex-dividend date. The ex-dividend date is normally set for stocks two business days before the record date. If you purchase a stock on its ex-dividend date or after, you will not receive the next dividend payment. Instead, the seller gets the dividend. If you purchase before the ex-dividend date, you get the dividend.