U.S. stocks tumbled to session lows Thursday

NEW YORK (MarketWatch)
U.S. stocks tumbled to session lows Thursday just ahead of the closing bell as investors fretted about the outcome of a European Union summit scheduled to conclude Friday.
The Dow Jones Industrial Average ended at 11,997.70, off 198.67 points or 1.6%.
The S&P 500 declined 26.66 points, or 2.1%, to 1,234.35.
The Nasdaq Composite dropped 52.83 points, or 2%, to 2,596.38.
"The market has become completely untradeable with all that is going on in Europe," Peter Boockvar, equity strategist at Miller Tabak, wrote in emailed commentary