Dow jumps 271 points, S&P 500 extends win streak, Nasdaq sheds 0.18%

U.S. stocks closed mixed Thursday, with the S&P 500 rising 0.4% to log a fourth straight day of gains, while the Dow Jones Industrial Average climbed more than 250 points.  The Nasdaq Composite dipped 0.2%, breaking its six-day winning streak.…