The S&P 500 snapped its seven-day winning streak Friday after Federal Reserve Chair Jerome Powell’s discussion of tapering made investors skittish. He said the Fed was “on track” to begin reducing its massive asset purchases. The market often brushes off such comments, but not now with the major indexes trading at stratospheric heights, said GuideStone Capital Management’s Brandon Pizzurro. “We are now close to all-time highs. Once again, I don't know how many times we've said that this year, but now when you mix tapering that's going to be very soon, imminent, even perhaps with where we are from a market cap and valuation standpoint, people just have to take a pause and see where we are.” A rally in shares of American Express on strong earnings helped lift the Dow a fifth of a percent. But disappointing quarterly reports from Snap and Intel drove the S&P down a tenth percent, and the Nasdaq eight-tenths percent. Still, the major indexes gained ground for a third straight week. On Friday, Snap shares plunged after the owner of photo messaging app Snapchat warned about weakness in its advertising business. That made investors shudder about the earnings prospects of other ad-dependent social media giants, dragging down shares of Facebook, Twitter, and Google parent Alphabet. Intel shares dropped after the semiconductor maker’s sales fell short of analysts’ expectations. Its CEO blamed chip shortages for holding back sales of its flagship processors.