Solange Maria Guerra

Banking concentration and the price-concentration relationship: the case of Brazil

In this paper, we present a new measure of concentration that employs duality theory and a study on the evolution of banking concentration in the Brazilian banking system. We present evidence suggesting that this new measure of concentration is more informative than the usual Hirschman-Herfindahl Index (HHI), which is commonly employed in concentration studies. Finally, we study the relation between the banking structure (level of concentration) and price using a panel data model, macroeconomic and risk variables being controlled. There is no evidence that banking concentration leads to uncompetitive practices.

Stock returns and volatility: the Brazilian case

This paper examines the relationship between stock returns and volatility over the period of June 1990 to April 2002. We study firm-level relationship between stock returns and volatility for a sample of 25 time series of Brazilian stocks. Using Seemingly Unrelated Regressions (SUR) empirical evidence suggests that contemporaneous returns and volatilities are significantly and positively correlated while there is a negative relationship between changes in volatility and stock returns. Finally, the asymmetric volatility effect seems to hold for Brazilian stocks as shown by the results from an AR(1)-EGARCH(1,1) estimation.