Efficient Markets Hypothesis
Efficient Market Hypothesis (EMH) states that it is impossible to "beat the market" because the price reflects all publicly available information on all traded securities
Weak Form EMH
The week form states that all information contained in past price movements is reflected in the price
Semi-Strong Form EMH
The semi-strong from states that all public information about the security is already reflected in the price
Strong Form EMH
The strong form states that all information about the security is already reflected in the price