Some investors may have gotten early word of changes to Federal Reserve policy between 1997 and 2013 and profited by trading before the policy shifts were publicly announced, according to Singapore-based researchers. Trading records show abnormally large price movements and imbalances in buy and sell orders that are \”statistically significant and in the direction of the subsequent policy surprise,\” according to a paper by Gennaro Bernile, Jianfeng Hu and Yuehua Tang at Singapore Management University.