The semistrong form claims that all publicly available information is reflected in securities prices, while the strong form argues that all information is reflected.  
One problem in testing this theory is that serial correlations may be the result of time varying rates and premiums. Technical analysis assumes that market action discounts everything, and that certain price formations are recurrent, thus violating a form of this theory. Another challenge to this theory is posed by possible limits to arbitrage and human psychology, the tenets that underlie behavior finance.  Developed by Eugene Fame, the theory comes in three varieties. The weak form asserts that all past market prices and data are fully reflected in securities prices. The semistrong form claims that all publicly available information is reflected in securities prices, while the strong form argues that all information is reflected.  FTP, identify this economic theory which claims that predicting the market on a long term basis is impossible.
One problem in testing this theory is that serial correlations may be the result of time varying rates and premiums.
the Efficient Markets Hypothesis