NEW YORK (Reuters) - Stocks rose at the open on Friday, putting the S&P 500 on track for its longest winning streak in eight years, buoyed by rosy earnings from Procter & Gamble amid a backdrop of sturdy corporate results. The Dow Jones industrial average gained 16.82 points, or 0.12 percent, to 13,842.15. The Standard & Poor's 500 Index rose 2.48 points, or 0.17 percent, to 1,497.30. The Nasdaq Composite Index advanced 9.48 points, or 0.30 percent, to 3,139.86. (Reporting by Chuck Mikolajczak; Editing by Bernadette Baum)