This is an interesting phenomena in the stock market which provides a secure profit. My guess it is a result of purchases for the purpose of getting the dividend and then selling until the next dividend. Looking at the chart for the past year:
note that there is a slight run up before each dividend and then a turn down after the dividend date. Yesterday I sold 34.5 calls for 98 cents and today I can buy them back for 15 cents but no need to do so because they will probably expire worthless on Friday (they are weekly options). It isn't all profit because I have to pay $.45 cents per share to cover the dividend, but 50 cents a share profit ain't bad for such a low risk investment that I didn't put any money into.