SAN FRANCISCO (MarketWatch) -- U.S. stocks zigzagged Wednesday after the Federal Reserve said it will continue its $85-billion-a-month in asset purchases. Following the Fed news, stocks spiked, dropped, and spiked again only to return to near levels before the announcement. The Dow Jones Industrial Average was down 24 points, or 0.2%, at 15,657. The S&P 500 Index fell 5 points, or 0.3% to 1,767. The Nasdaq Composite Index declined 11 points, or 0.3%, to 3,941.