Resumen
This paper examines how regulatory interventions can affect the market risk of electricity utilities and telecom carriers traded in the Brazilian stock market (BOVESPA). Our article uses a bivariate Generalized AutoRegressive Conditional Heteroskedasticity (GARCH - BEKK) model to analyze the impact of two relevant and surprising measures taken by the correspondent Brazilian regulatory authorities in 2012 (one in each sector) on both markets? volatilities and covariance. We also adopt the volatility impulse response function (VIRF) developed by Hafner & Herwartz (2006) to estimate their persistence. On the one hand, the results indicate that the effects of the telecommunications? regulatory intervention are negligible but, on the other hand, the impact of the electricity's regulatory measure is significant, long-lasting and contagious.