The Oracle of Omaha's "hidden" $602 million portfolio has been a decisive seller of three brand-name companies on the cutting edge of the artificial intelligence (AI) revolution.Few if any money managers command the attention of professional and everyday investors quite like Berkshire Hathaway (BRK.A -0.34%) (BRK.B -0.96%) CEO Warren Buffett. Since becoming CEO in the mid-1960s, he's overseen a cumulative return in his company's Class A shares (BRK.A) of more than 5,500,000%, and briefly witnessed his compa ...