Here is the real story:
On Oct 23 FB closed at $19.50 and reported earnings after hours. On Oct 24th the high os the day was 24.25 which is a gain of $4.75 . In 9 trading days it was back to $19.21 which is a loss of $5.04. Or -.17 cents loss from before earnings.
Earnings came out on the 23rd last QTR. The next day it was up $3.75 from 19.50 to 23.23. It fell back down to 19.21 where it has been on the rise since. If earnings and guidance are good in this report I think a 7-10% move is a realistic target. (the key is here "guidance" it doesn't matter if they meet or beat earnings if they say something stupid or negative about the future expect a big sell off).