Using high‐frequency, granular panel data on short‐term debt securities issued in Europe, we study the existence, empirical boundaries, and fragility of private assets' safety. We show that only securities with the shortest maturities, issued by banks (certificates of deposit, or CDs), benefit from a safety premium. The supply of such CDs responds positively to excess safety demand. During periods of stress, this relation vanishes for all issuers of private securities, even though their aggregate volumes do not collapse. Other dimensions of heterogeneity, including issuers' balance sheets or their domicile countries' fiscal capacity, are less relevant for private safety.

We propose a new definition of skill as general cognitive ability to pick stocks or time the market. We find evidence for stock picking in booms and market timing in recessions. Moreover, the same fund managers that pick stocks well in expansions also time the market well in recessions. These fund managers significantly outperform other funds and passive benchmarks. Our results suggest a new measure of managerial ability that weighs a fund's market timing more in recessions and stock picking more in booms. The measure displays more persistence than either market timing or stock picking alone and predicts fund performance.

Despite extensive disclosure requirements, mutual fund investors do not observe all actions of fund managers. We estimate the impact of unobserved actions on fund returns using the return gap—the difference between the reported fund return and the return on a portfolio that invests in the previously disclosed fund holdings. We document that unobserved actions of some funds persistently create value, while such actions of other funds destroy value. Our main result shows that the return gap predicts fund performance. (JEL G11, G23) Despite extensive disclosure requirements, mutual fund investors do not observe all actions of fund managers. For example, fund investors do not observe the exact timing of trades and the corresponding transaction costs. On the one hand, fund investors may benefit from unobserved interim trades by skilled fund managers who use their informational advantage to time the purchases and the sales of individual stocks optimally. On the other hand, they may bear hidden costs, such as trading costs, agency costs, and negative investor externalities. In this paper, we analyze the

Mutual fund managers may decide to deviate from a well‐diversified portfolio and concentrate their holdings in industries where they have informational advantages. In this paper, we study the relation between the industry concentration and the performance of actively managed U.S. mutual funds from 1984 to 1999. Our results indicate that, on average, more concentrated funds perform better after controlling for risk and style differences using various performance measures. This finding suggests that investment ability is more evident among managers who hold portfolios concentrated in a few industries.