Berkshire Hathaway’s latest quarterly filing reveals that Buffett has added to his stake in oil producer ConocoPhillips and bought shares of the manufacturer Eaton Corp. He reduced his holdings in Bank of America Corp. Berkshire is now ConocoPhillips largest shareholder.

According to a 2007 academic study by Gerald Martin of American University and John Puthenpurackal of University of Nevada, if an investor would have followed Berkshire’s purchases, even with the delayed notice, they would have generated a return of 25% annually from 1976 to 2006.