1.   Ex-dividend means shareholders who buy the stock starting today will not receive the next dividend payout.

2.   Gains were also held back by companies that went ex-dividend, meaning investors who buy today will not be eligible to receive the next dividend.

3.   Investors who sell shares in SAP today will still receive the next dividend payout.

4.   Investors can sell ex-dividend stocks and still receive the next dividend payment.

5.   Other decliners included stocks that traded ex-dividend today, which means shareholders can sell the stock and still receive the next dividend payout tomorrow.

6.   Part of the decline was because the shares went ex-dividend today, meaning shareholders can sell the stock and still receive the next dividend.

7.   Shares going ex-dividend -- meaning shareholders can sell the stock from today and still receive the next dividend -- were among the biggest losers.

8.   Some investors sell stock knowing they are eligible for the next dividend payment.

9.   Some leading companies went ex-dividend, with shareholders losing their right to the next dividend payment as of today.

10.   Stocks often decline on the day they go ex-dividend because a shareholder can sell the stock and still collect the next dividend.