Our simulation results show that tests for long-horizon (i.e.. multi-year) abnormal security returns around firm-specific events are severely misspecified. The rejection frequencies using parametric tests sometimes exceed 30% when the significance level of the test is 5%. Our results are robust to many different abnormal-return models. Conclusions from long-horizon studies require extreme caution. Nonparametric and bootstrap tests are likely to reduce misspecification.

We examine the proportion of a stock's cumulative price change that occurs in each trade-size category, using transactions data for a sample of NYSE firms. Although the majority of trades are small, most of the cumulative stock-price change is due to medium-size trades. This evidence is consistent with the hypothesis that informed trades are concentrated in the medium-size category, and that price movements are due mainly to informed traders' private information.

We study standard mutual fund performance measures, using simulated funds whose characteristics mimic actual funds. We find that performance measures used in previous mutual fund research have little ability to detect economically large magnitudes (e.g., three percent per year) of abnormal fund performance, particularly if a fund's style characteristics differ from those of the value‐weighted market portfolio. Power can be substantially improved, however, using event‐study procedures that analyze a fund's stock trades. These procedures are feasible using time‐series data sets on mutual fund portfolio holdings.

BANKRUPTCY COSTS are the deadweight economic costs of firms going bankrupt. They include both ex post bankruptcy costs incurred after a firm's bankruptcy filing, such as transactions costs, and ex ante bankruptcy costs incurred before the filing, such as those resulting from creditors' attempts to reduce their losses if bankruptcy occurs and/or managers' attempts to raise the expected return to equity by increasing the firm's risk.1 This paper has two purposes. First it proposes a model of bankruptcy costs which focuses on the costs of inefficient decision making before the firm's actual bankruptcy filing. The model implies upper bound expressions for total bankruptcy costs. Second, the new U.S. Bankruptcy Code2 went into effect late in 1979 and made important changes in bankruptcy reorganization procedures. The paper poses the question of whether the changes made under the new Code tend to raise or lower aggregate U.S. bankruptcy costs. We approach this question by calculating the upper bound expressions suggested by the model, using parameter values from both before and after the new Code took effect.

We study put option sales on company stock by large firms. An often‐cited motivation for these transactions is market timing, and managers' decision to issue puts should be sensitive to whether the stock is undervalued. We provide new evidence that large firms successfully time security sales. In the 100 days following put option issues, there is roughly a 5% abnormal stock return, with much of the abnormal return following the first earnings release date after the sale. Direct evidence on put option exercises reinforces these findings: exercise frequencies and payoffs to put holders are abnormally low.