U.S. stocks slumped in the final minutes of trading Friday and ended a rough week with more losses. Bad news from sporting goods retailers weighed on the market. On Friday: The S&P 500 retreated 4.46 points, or 0.2 percent, to 2,425.55. The Dow Jones industrial average declined 76.22 points, or 0.3 percent, to 21,674.55. The Nasdaq composite sank 5.39 points, or 0.1 percent, to 6,216.53. The Russell 2000 index of smaller-company stocks slipped 1.15 points, or 0.1 percent, to 1,357.79. For the week: The S&P 500 lost 15.77 points, or 0.6 percent. The Dow fell 183.81 points, or 0.8 percent. The Nasdaq dipped 40.03 points, or 0.6 percent. The Russell 2000 tumbled 16.44 points, or 1.2 percent. For the year: The S&P 500 is up 186.