The relationship between idiosyncratic risk and stock returns has been widely studied in various international publications with controversial results. In the Brazilian context, studies on this subject are scarce. This study seeks to verify the relationship between idiosyncratic risk and stock returns in the Brazilian stock market. To achieve this goal, two methods were used to estimate idiosyncratic volatility: first, the residuals of regressions based on the Fama and French Three-Factor Model and second, the EGARCH model, which provided the conditional volatility. These variables were added to cross-section regression models, along with the following stock-specific variables: beta, market value, book-to-market ratio, momentum effect and liquidity. The results show that idiosyncratic volatility has a positive and significant influence on stock returns and that the most appropriate model is the one that includes all the mentioned variables. The analysis of the other variables also produced important results. Contrary to expectations, the market value of stocks and liquidity had an important influence on returns. These variables' coefficients were positive in all the analyzed models. This result may reflect the particularities of the Brazilian market, which is smaller, more recent and less consolidated than the USA stock market. On the other hand, the results relating to the book-to-market ratio and the momentum effect were consistent with the literature. Value stocks and those with a good past performance tended to produce higher returns.
Idiosyncratic risk; Stock market; Stock returns; EGARCH model; Three-Factor model
