The efficient market hypothesis (EMH) maintains that all stocks are perfectly priced according to their inherent investment properties, the knowledge of which all market participants possess equally. It holds that when new information comes into the market, it is immediately reflected in stock prices. There are three tenets to the efficient market hypothesis: the weak, the semi-strong, and the strong. The weak form suggests that today’s stock prices reflect all the data of past prices and that no form of technical analysis (the study of past stock prices in an attempt to predict future prices) can be effectively utilized to aid investors in making trading decisions. Therefore, it assumes that technical analysis can't be used to achieve returns.