efficient-market hypothesis

…changed understanding of the “efficient market hypothesis,” which held that securities prices in an efficient stock market were inherently unpredictable—that is, an investment in the stock market was, for all but insider traders, equivalent to gambling in a casino. (An efficient stock market was one in which all information…

…to the development of the efficient-market hypothesis and the empirical analysis of asset prices. Fama showed that it is very difficult to predict asset-price movements in the short run, because markets incorporate any new price-relevant information very quickly. This finding came to be known as the efficient-market hypothesis, and it…

…topics in finance is the efficient-market hypothesis, developed by Eugene Fama in 1965. In a nutshell, the theory says that the financial markets are efficient, so no one can gain an edge in them.