253224000 (over 253 million) shares sold by insiders including 36 million by MZ.
In case you have not checked the SEC fillings, and contrary to Zuck promise, he sold 18 million shares in 2 different occasions for a total of 36 million shares.
Also, the issue here is not that insiders sold shares. The issue is that they sold such an enourmous number of shares that it equals to nearly 20-25% of the total float. The other issue also is that they did not just unload to load back up when the pps goes down as they basically bought zip even when pps was down to 17 and change. Go figure.