Knowledge that Transforms

Using end-of-month bid-ask spreads for 540 NYSE stocks over the period 1982–1987, we document a seasonal pattern in which both relative and absolute spreads decline from the end of December to the end of the following January. Cross-sectional regressions do not, however, provide evidence of a significant correlation between changes in spreads at the turn of the year and January stock returns. Either there is no cause and effect relation between the coincidental seasonals in bid-ask spreads and January returns for NYSE stocks or the data are too “noisy” to reveal any relation.

OLS regression ignores both heteroscedasticity and cross-correlations of abnormal returns; therefore, tests of regression coefficients are weak and biased. A Portfolio OLS (POLS) regression accounts for correlations and ensures unbiasedness of tests, but does not improve their power. We propose Portfolio Weighted Least Squares (PWLS) and Portfolio Constant Correlation Model (PCCM) regressions to improve the power. Both utilize the heteroscedasticity of abnormal returns in estimating the coefficients; PWLS ignores the correlations, while PCCM uses intra-and inter-industry correlations. Simulation results show that both lead to more powerful tests of regression coefficients than POLS.

Restrictions on trading by insider agents are analyzed using an optimal contracting framework. Prohibition of insider trading is shown to be Pareto preferred if, and only if, a revelation or moral hazard problem exists. If prohibition of insider trading is valuable, then trade registration with a delay is shown to be as valuable as complete prohibition. Short selling restrictions, however, are generally of less value than complete prohibition. Finally, regulation of insider agent trading by governmental institutions and/or professional associations is discussed.

Recent theoretical work has argued that a small open economy should use residence-based but not source-based taxes on capital income. Given the ease with which residents can evade domestic taxes on foreign earnings from capital, however, a residence-based tax may not be administratively feasible, leaving no taxes on capital income.