[gwern]

The way I remember it, it was simply that men traded more and so the fees (combined with some bad choices) damaged their returns: http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.145...

[yummyfajitas]

This paper is based on retail investors at a discount brokerage, not asset managers.

[gwern]

Who we would expect to be immune to the issues of their gender... why? I bet if you look, there are similar results for managers, that those who trade more damage their returns.

[yummyfajitas]

Because the asset managers who are not immune to the problems of retail investors get fired very quickly.

Just as it is hard to generalize from your average facebook user to programmers, it is hard to generalize from retail investors to professional traders.