1. Efficient Market Hypothesis:stock's price represents the BEST ESTIMATE of its true value.
2.Random Walk Theory:past price changes contain NO USEFUL INFORMATION on which to base decisions.
3.Rational Expectations Hypothesis:past mistakes CAN BE AVOIDED by using information to anticipate change.
1. New information not available to all at the same time.
2.All investors do not react to all information in the same way.
3.All investors do not make accurate forecasts and correct decisions.
存在各种不完美和时间差，才是完美的市场理论。They still work, focus on the good.