On Monday Twitter reported slowing user growth setting up that stock to open down 13% the following day. Tuesday Facebook told investors that its costs will rise between 50% and 70% next year — shares opened down 6.6% Wednesday. Initially its seemed LinkedIn would complete the crummy social earnings trifecta as the stock tumbled as much as 7% following its after-hours release Thursday. But about 45 minutes after the closing bell the stock was up more than 2.5% to around $208.50. ...