ADVERTISEMENTBillionaire investor Warren Buffet said on Saturday that he wants to step down as chief executive of Berkshire Hathaway at the end of the year. The revelation came as a surprise as the 94-year-old had previously said he did not plan to retire.Buffett, one of the world's richest people and most accomplished investors, took control of Berkshire Hathaway in 1965 when it was a textiles manufacturer. He turned the company into a conglomerate by finding other businesses and stocks to buy that were selling for less than they were worth.His...