Professional traders have known this for decades. Watching for signs of insider movement and then jumping on has been a popular strategy since forever. (Of course, you have to know how to read the charts... the signs are subtle and ambiguous.)

I sometimes wonder if we wouldn't be better off without the charade of insider trading laws. We could just drop them and stop pretending the water isn't shark-infested. Ironically, Wall Street might oppose this as it might make it harder to attract suckers to the game (if I may mix metaphors).