U.S. stocks finished at record levels Thursday as investors set aside worries over the ongoing government shutdown and continued to push major indexes higher.The S&P 500 gained 0.06 percent to end at 6,715.35. The index briefly rose 0.3 percent earlier in the day to mark a fresh intraday high. The Dow Jones Industrial Average added 78.62 points, or 0.17 percent, closing at 46,519.72. The Nasdaq Composite advanced 0.39 percent to finish at 22,844.05. Both the S&P 500 and Nasdaq closed at their highest levels ...