Berkeley professor Terry Odean published an interesting paper in the Quarterly Journal of Economics in 2001 about how men and women invest differently. It was an empirical study based on stock transaction data in tens of thousands of accounts over a seven year period provided by a brokerage firm.

These investment accounts were either opened by a man or a woman, and were single or joint accounts. Thus there were four account types. An interesting phenomenon emerged from the study: the more a man is in control of an account, the worse the performance. (See net return vs benchmark.)

Here the benchmark is not any composite index, it is simply the return that resulted from no trades being made throughout the whole year. 

One thing is very clear, both men and women reduce their account returns by trading instead of just doing nothing . (That’s why I’d rather err on the side of inaction while managing clients’ investments.) Furthermore, the return reduction is largest for man-single accounts, followed by man-joint accounts. Women-single accounts have the smallest return reduction, followed by women-joint accounts.