U.S. stocks ended narrowly mixed on Tuesday amid concerns about the European debt crisis and mixed U.S. corporate earnings. The Dow Jones Industrial Average lost 33.07 points, or 0.26 percent, to 12,675.75. The Standard & Poor\'s 500 Index dipped 1.37 points, or 0.10 percent, to 1,314.63. The Nasdaq Composite Index added 2.47 points, or 0.09 percent, to 2,786.64. Investors were disappointed that talks between Greece and its private bondholders to write down the country\'s debt by 100 billion euros have yet to result in a final agreement as negotiations stalled over the weekend. Meanwhile, European Union financial ministers on Tuesday rejected the proposals by private Greek debt holders of a 65 to 70 percent write-down of the country\'s debt. The news added to concerns about the European debt crisis. Adding to pressures, Christine Lagarde, managing director of International Monetary Fund (IMF), said the organization needed an additional 500 billion U.S. dollars to help resolve the European debt crisis. However, the source of the money remained unclear. Some key companies reported earnings on Tuesday, but the results turned out to be mixed. Fast food giant McDonald\'s dropped more than 2 percent after the company said its fourth-quarter profit climbed 11 percent but projected that 2012 earnings per share may be impacted 16 cents to 18 cents on foreign currency translation, primarily driven by a weaker euro. The Travelers Companies, another Dow component reporting earnings on Tuesday, tumbled more than 3.5 percent, after the insurance company posted earnings that missed market expectations. Both Apple and Yahoo will announce its fourth-quarter warnings after the market closes, which may help set the tone for Wednesday \'s trading.