Ex-dividend dates are used to make sure dividend checks go to the right people. In today's market, settlement of stocks is a T+3 process, which means that when you buy a stock, it takes three days from the transaction date (T) for the change to be entered into the company's record books.
As mentioned, if you are not in the company's record books on the date of record, you won't receive the dividend payment. To ensure that you are in the record books, you need to buy the stock at least three business days before the date of record, which also happens to be the day before the ex-dividend date.
As you can see by the diagram above, if you buy on the ex-dividend date (Tuesday), which is only two business days before the date of record, you will not receive the dividend because your name will not appear in the company's record books until Friday. If you want to buy the stock and receive the dividend, you need to buy it on Monday. (When the stock is trading with the dividend the term cum dividend is used). But, if you want to sell the stock and still receive the dividend, you need to sell on or after Tuesday the 6th.
SUMMARY : EX-Dividend Date -- 2 Business days before RECORD DATE
Need to buy the shares a day before to EX-Dividend Date.
We can SELL the Shares on EX-Dividend Date +2 days provided if you hold the shares already, In this case you will get the Dividend too.
