The EMH stands for the Efficient Market Hypothesis (aka Efficient Market Theory) and it's an investment theory about how share prices reflect all the information available on those shares. Shares are always traded at their fair value and it is therefore impossible to buy undervalued or sell overpriced stocks. In English, it suggests that the market can't be beaten. There is strong support for this theory (e.g. index funds tend to do a lot better than mutual funds in efficient