I happened to have a set of standing instructions for a number of technology companies which consisted of buying stock when it dropped more than 5% below the 90 moving average, and selling stock when it exceeded more than 5% the 90 day moving average.
For a lot of tech companies this was basically a money pump since they rose and fell quite cyclically. Then I went to work at one of the companies on my list (NetApp) and one quarter EMC announced they were going to miss their earnings and all storage companies dropped. Two weeks later NetApp announced their earnings which were better than expected.
When I got my brokerage statement for the month I had a nice gain because they had bought NetApp on the dip, and then when the earnings were announced the stock went up so they sold the shares that had been bought. About three weeks after that I got a call from the SEC. I referred them to my broker which showed both the standing order, and that they had been in place for a couple of years before that event, and the SEC went away. However I did take NetApp out of the mix because, well it is always unnerving when your phone tells you the SEC is calling. :-).