There were no significant changes in U.S. stock indices during a short trading session on Friday, in observance of Thanksgiving, as investors focused on retail companies with the start of Black Friday sales amid signs of an economic slowdown. The Dow Jones Industrial Average rose by 26.87 points, or 0.08%, to 35,299.90 points, while the S&P 500 opened down 0.78 points, or 0.02%, at 4,555.84 points. In contrast, the Nasdaq Composite fell by 27.82 points, or 0.20%, to 14,238.04 points.