 Market efficiency implies that stock prices fully reflect all publicly available information instantaneously; thus no investment strategies can systematically earn abnormal returns.Fama (1991) argued that stock prices respond instantaneously and without bias to their new values based on new, relevant information and that security returns over time are determined only by changes in the market level and individual stock risk.Therefore, there are no profitable investment opportunities from superior analysis, which implies no one can consistently outperform the market.