(Reuters) Stocks opened little changed on Tuesday as investors continued to cautiously view the ongoing sovereign debt crisis in Europe.

S&P issued a downgrade warning for the region late Monday, but investors had some hope the threat would help force budget changes at a European Union summit this week.

The Dow Jones industrial average was up 16.57 points, or 0.14 percent, at 12,114.40. The Standard & Poor's 500 Index added 0.41 points, or 0.03 percent, at 1,257.49. The Nasdaq Composite Index put on 2.15 points, or 0.08 percent, at 2,657.91.