Group of investors known as "Hot Money". They move money to a manager who appears to have a hot hand... likely very good results last year. But as soon as the manager no longer appears to be "hot", investors pull out and go looking for the next hot hand. Don't know how that works overall, but there appears to be correlation. IOW.. just because you made a good score last year doesn't necessarily mean you're brilliant. Seems the only group of market players who can consistently make above average returns are the best HFTs... you know, the ones who are faster at front-running trades than the other HFTs.