Temporary deviations of trade prices from fundamental values impart bias to estimates of mean returns to individual securities, to differences in mean returns across portfolios, and to parameters estimated in return regressions. We consider a number of corrections, and show them to be effective...

The well-documented abnormal long-run buy-and-hold returns to firms issuing equity in initial public offerings and seasoned equity offerings, firms bidding in mergers, and firms initiating dividends can be attributed to imperfect control-firm matching. In addition to firm size and market-to-book...

We examine whether stock prices fully reflect the value of firms' intangible assets, focusing on research and development (R&D). Since intangible assets are not reported on financial statements under current U.S. accounting standards and R&D spending is expensed, the valuation problem may be...

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...

Investment performance depends on return measurement horizon. The percentage of U.S. equity mutual funds that outperform the SPY is 46.9% in monthly returns, 39.9% in annual returns, and 29.5% in full-sample (1991-2008) returns. Further, true alphas vary with return measurement horizon, and the...