If you buy shares to invest in a company and keep them, then the rise and fall of the price would not affect you too much. However if you buy them because you want a gamble then look at it this way, Monday you pay 50p each for some shares on Friday they are down too 40p you will loose 10p for each share purchased, if you sell them, keep them and the following month the may be 60p. It all depends on what you wish to do, keep them or gamble.