The Oracle of Omaha has concentrated Berkshire's investment portfolio in his best ideas.Few if any money managers command the attention of professional and everyday investors quite like the "Oracle of Omaha," Warren Buffett. Since becoming the CEO of Berkshire Hathaway (BRK.A 0.56%) (BRK.B 0.69%) in the mid-1960s, he's overseen a cumulative return of more than 5,700,000% in his company's Class A shares (BRK.A), as of the closing bell on Nov. 18.Aside from crushing Wall Street's benchmark index -- the S&P 50 ...