What I found interesting was that former employees made up the largest group of sellers, at 64.5%, followed by existing employees at 16.9%, investors at 8.4%, founders at 3.6%, and "other" constituting the remainder. What interested me here was not that former employees were the largest group, but size of the differential between former employees and existing employees/founders.
The article also lists the top 10 "most watched" companies on its service, which includes Facebook, Twitter, Groupon, Zynga and Foursquare. There are also listings of "Rising Stars" and "Newbies" which contain a number of companies that I was not familiar with, but will now certainly watch.