Thomson Financial maintains a great page Insider Activity Tearsheet tracking the overall insider trading activities in the market. It displays the insider buying and selling activities by month, by market cap, my index and by industry. The page also provides links to detailed industry-level analysis.
The data is talking: since August, insider selling is always at least 17 times higher than insider buying in dollar terms. For the month of February, $9.0 billion worth insider selling is logged in conjunction with paltry insider buying of $175 million.
I can understand some level of inequality in insider selling vs buying: if I get rich, I may want to diversify my net worth by periodically liquidating my holdings in one company. However, a magnitude of 10 times or even more makes me nervous. I can only perceive this as another sign of overvaluation of the overall market.