MARKET EFFICIENCY

The degree by which stock prices reflect all available and relevant information, which gives maximum opportunities to market makers to have an effective transaction with minimal transaction costs. Economist Eugene Fama developed market efficiency in 1970, from his Efficient Market Hypothesis (EMH) that explains it is impossible for an investor to outperform the market, given that all available information is already seen in all stock prices. Traders who agree with the theory are inclined to purchase index funds in order to track market performance in general.