Buttonwood The secrets of Buffett’s success Beating the market with beta Sep 29th 2012 | from the print edition The Economist IF INVESTORS had access to a time machine and could take themselves back to 1976, which stock should they buy? For Americans, the answer is clear: the best risk-adjusted return came not from a technology stock, but from Berkshire Hathaway, the conglomerate run by Warren Buffett. Berkshire also has a better record than all the mutual funds that have survived over that long period. Some academics have discounted Mr Buffett as a statistical outlier. Others have simply stood in awe of his stock-picking skills, which they view as unrepeatable. But a new paper * from researchers at New York University and AQR Capital Management, an investment manager, seems to have identified the main factors that have driven the extraordinary record of the sage of Omaha. Understanding the success of Mr Buffett requ...