We evaluate the performance of different models for the covariance structure of stock returns, focusing on their use for optimal portfolio selection. Comparisons are based on forecasts of future covariances as well as the out-of-sample volatility of optimized portfolios from each model. A few...

We examine long-run firm performance following open market share repurchase announcements which occurred during the period 1980 to 1990. We find that the average abnormal four-year buy-and-hold return measured after the initial announcement is 12.1 percent. For `value' stocks, companies more...

We evaluate the performance of different models for the covariance structure of stock returns, focusing on their use for optimal portfolio selection. Comparisons are based on forecasts of future covariances as well as the out-of-sample volatility of optimized portfolios from each model. A few...