Imagine buying a stock and then calling up billionaire investor Carl Icahn and saying: Carl, I want you to pay Lazard $50 million to get them to come up with a plan to get this stock higher. I want you to dish out another $5 million in legal fees. I want you to alert the media and really bang the drum on this one. You got that, Carl? And, listen, if you mess up (insert Donald Trump voice here) , you're fired. Got that? Well, you can do that with every trade. That's the main impetus behind a Web site like Stockpickr. When you can "piggyback" a hedge fund (i.e., buy positions that it's buying, maybe at even cheaper prices than it's paying), it's as if you are hiring that fund to do all the dirty work while you get to trade in and out of stocks without much fuss. And there are three main reasons why piggybacking an activist hedge fund -- a fund that's going to take a large position in a company and start shaking all of the trees -- is particularly worthwhile. One, these funds do a lot of research to find hidden value. Activists typically move in where the value isn't immediately obvious and they press management to unlock that value (for instance, trying to get McDonald's ( MCD) to sell real estate holdings). Two, these funds are typically long-term holders. Activists tend to take 5% or greater positions in a company. They aren't able to nimbly trade out of those positions.