In Appendix A, we document that accounting for the exact timing of trades
would reduce the performance of individual investors by about two basis
points per month. In Appendix B, we document that accounting for intramonth
trades would improve the performance of individual investors reported
in our main results by less than one basis point per month. More
important, a careful accounting for both the exact timing of trades and the
profitability of intramonth trades indicates that the results we report in the
main text are slightly high for our full sample and for every sample partition
that we analyze.
Consider the common stock portfolio for a particular household. The gross
monthly return on the household’s portfolio