The buying of stock implies the purchase of part of the ownership of the company. The price for the first issue are generally determine by the board of directors of the company. After the initial sale, the stocks are traded freely in the market. At this point the market value of the stock is determined by the force of supply and demand in various money points,by way of custom these points are measured. Stock are generally listed in alphabetical order in newspapers.
In the case of selling stock, as a general principle operators in the stock market buy at low prices and sell at high prices. A successful investor must pay attention to his portfolio of securities and meticulously deciding which and when to sell or buy. A reason to sell could be that the stock has not performed as well as expected or simply because money is needed for some other purposes.