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YOSHINAGA, C. E. The Relationship between Market Sentiment Index and Stock Returns: a Panel Data Analysis. 162p. Thesis (Doctoral)

This article analyzes the relationship between market sentiment and future stock rates of return. We used a methodology based on principal component analysis to create a sentiment index for the Brazilian market with data from 1999 to 2008. The sample consisted of companies listed on BM&FBOVESPA which were grouped into quintiles, each representing a portfolio, according to the magnitude of the following characteristics: market value, total annualized risk and listing time on BM&FBOVESPA. Next, we calculated the average return of each portfolio for every quarter. The data for the first and last quintiles were analyzed via two-factor ANOVA, using sentiment index of the previous period (positive or negative) as the main factor and each characteristic as controlling factors. Finally, the sentiment index was included in a panel data pricing model. The results indicate a significant and negative relationship between the market sentiment index and the future rates of return. These findings suggest the existence of a reversion pattern in stock returns, meaning that after a positive sentiment period, the impact on subsequent stock returns is negative, and vice-versa.

The disposition effect predicts that investors tend to sell winning stocks too soon and ride losing stocks too long. Despite the wide range of research evidence about this issue, the reasons that lead investors to act this way are still subject to much controversy between rational and behavioral explanations. In this article, the main goal was to test two competing behavioral motivations to justify the disposition effect: prospect theory and mean reversion bias. To achieve it, an analysis of monthly transactions for a sample of 51 Brazilian equity funds from 2002 to 2008 was conducted and regression models with qualitative dependent variables were estimated in order to set the probability of a manager to realize a capital gain or loss as a function of the stock return. The results brought evidence that prospect theory seems to guide the decision-making process of the managers, but the hypothesis that the disposition effect is due to mean reversion bias could not be confirmed.KEYWORDS | Loss aversion, disposition effect, prospect theory, mean reversion, logistic regression. RESUMO RAE-Revista de Administração de Empresas | FGV-EAESP

Behavioral Finance in Brazil: applying the prospect theory to potential investors Finanças Comportamentais no Brasil: uma aplicação da teoria da perspectiva em potenciais investidores Finanzas comportamentales en Brasil: aplicación de la teoría de la perspectiva a los inversores potenciales