US STOCKS-Earnings cloud drags down Dow; Nasdaq gains on biotech M&A By: Reuters: Company News April 21, 2015 at 16:54 PM EDT * Dow ends down 0.47 pct, S&P down 0.15 pct, Nasdaq up 0.39 pct (Adds detail on extended trade moves) Read More >> Related Stocks: Facebook Google, Inc. Microsoft Qualcomm, Inc. TravelersCompanies