Height and decay of the hypotheses of efficient markets

Vol. 23 No. 4 (2003)

Oct-Dec / 2003
Published October 1, 2003
PDF-Portuguese (Português (Brasil))
PDF-Portuguese (Português (Brasil))

How to Cite

Lima, Luiz Antônio de Oliveira. 2003. “Height and Decay of the Hypotheses of Efficient Markets”. Brazilian Journal of Political Economy 23 (4):531-46. https://doi.org/10.1590/0101-31572004-0612.

Height and decay of the hypotheses of efficient markets

Luiz Antônio de Oliveira Lima
Professor do Departamento de Economia da Escola de Administração e Economia de São Paulo da Fundação Getúlio Vargas – EAESP, São Paulo/SP, Brasil.
Brazilian Journal of Political Economy, Vol. 23 No. 4 (2003), Oct-Dec / 2003, Pages 531-546


Eugene Fama defines a market as efficient if it fully reflects the existing information about the fundamental values of a financial asset. According to this hypothesis this kind of market makes available to the agents the optimal options for investing their money, leading in consequence to an efficient allocation of capital. The aim of this article is to show that this condition in fact does not exist in economic reality and as consequence to discuss how the alternative forms of asset markets guide the process of investment. The alternative forms of allocation imply that economic agents do not follow the ideal model of “full rationality”, but that they follow one “weak form” consistent with decisions that must be taken in condition of uncertainty. This analysis will allow us to construct more realistic models of financial markets considering not only their conditions of normality as well as the circumstances that explain their instability and crises.

JEL Classification: G3.

Keywords: Efficient markets financial markets