Berkshire Hathaway ( BRK.A -0.62% ) ( BRK.B -0.52% ) CEO and world-beating investor Warren Buffett's every move is followed closely by investors. Whether it's looking for trends, opportunities to emulate the Oracle of Omaha, or even for signs that his decades of success are coming to an end, every new 13F that Berkshire files each quarter gets endless scrutiny.