Insider buying is a rarely understood indicator of what a stock or market is doing. This is usually due to the fact that there is so much insider buying and selling as a part of compensation plans and on behalf of management who have shares of their firm managed on their behalf.
Thinking about insider buying and selling, it should be pretty obvious that if the buying and selling is directly attributed to a manager's unscheduled decision, the actions are pretty indicative of what that manager's views are about their business and the market that the business is operating in. This story by Mark Hulbert discusses this concept in more depth with the view that Professor Nejat Seyhun indicating that the performance is forward looking 12+ months and not shorter term.
Interesting enough, there are some great examples of recent buying in $FXCM and $IGOI where the price is low and management is heavily adding to their positions on the open market. Granted the prices are cheap, but is there more to the story that we don't see in the 12+ month timeframe?
Considering most managers are buying or at least not selling, it would make sense that if insider selling were occuring, the manager's doing the selling would have a negative view of their firm in the 12+ month timeframe. This is a particularly revealing aspect that makes looking at $CRM a little more interesting as insiders there are selling (almost daily) and re-organizing their compensation plans and accounting schemes so that the expense of allocating shares (that management is selling, not holding) does not count against their "earnings" numbers. Definitely looks like management here also sees something in the 12+ month timeframe that we don't have access to.