Corporate governance and long-term stock returns

Extant literature finds that long-term abnormal stock returns are generated by a strategy based on corporate governance index values (Gompers, Ishii, and Metrick 2003). The result is inconsistent with efficient markets and suggests that information about governance is not accurately reflected in market data. Control firm portfolios are used to mitigate model misspecification in measuring long-term abnormal returns. Using a number of different matching criteria and governance indices, no long-term abnormal returns are found to trading strategies based on corporate governance. The effect of a change in governance on firm value is mixed, but some support is found for poor governance destroying firm value. These results have a number of implications for practitioners, researchers, and policy makers.