The facebook had a layered lock out period for insiders, the last one being at 366 days after IPO. I found it on a seeking alpha article from August 2012. That may be the real reason for this drop. That would mean this is a great opportunity to buy. The last one was 211 days after IPO.
There is no proof that insiders have been putting any significant selling pressure on this stock in the last three weeks. The price drop is also inconsistent with the trends of this sector and the company's data. The only thing I found here is a group of young white males posting negatives and misleading information about the company. What they are doing is actually illegal, meaning they are not suppose to be advising small investors to short, buy, sell or stay away from stocks. Why regulators are allowing them to do this is beyond belief. A person at SA actually sent out a hundred thousand emails last week telling people to short FB.
Also, the days to cover and the short interest does not even show them holding their short positions for long ( 1 day) and the short interest decreased this month. The bottom line is the recent price drop does not pan out with the overall trends of the company, the market and the sector. Aside from put options, the only thing they can be looking at is accounts of small investors.