Discover what makes markets informationally efficient, explore Eugene Fama's efficient market hypothesis, and understand the key criticisms of this concept.

Investopedia contributors come from a range of backgrounds, and over 25 years there have been thousands of expert writers and editors who have contributed. Amanda Bellucco-Chatham is an editor, writer ...

Weak form market efficiency is a concept that suggests past stock prices and trading volumes do not predict future stock prices. In a weak form efficient market, all historical information is already ...

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Many motors are labeled super, top, and premium efficient, but until a couple years ago, there wasn't any quantitative definition of the term. Then in Many motors are labeled super, top, and premium ...

In 1970, in “Efficient Capital Markets: a Review of Theory and Empirical Work,” Eugene F. Fama defined a market to be “informationally efficient” if prices at each moment incorporate all available ...