Dow briefly falls 100 points as Greece weighs; Twitter up 2%

U.S. stocks opened lower on Friday as negative news out of Greece weighed on sentiment and investors kept an eye on bond yields.

Dow briefly falls 100 points as Greece weighs; Twitter up 2% source: http://finance.yahoo.com/news/us-stocks-open-lower-greece-weighs-yields-eyed-133000083.html