Just note that the stock price is down below first day close. The original owners sold at open price which was 17. The price is now ~24, so its up nearly 40% since initial open.
some of the original owners might be "locked" and unable to sell for some time. if you say original investors - then that should be reported and available for public to see soon.
i believe that anyone who held significant stock prior to IPO is locked out of at least selling for a couple months - SEC probably has some regulations regarding that kind of thing.