10 S&P 500 stocks with the biggest declines over the past week By: MarketWatch July 27, 2015 at 13:36 PM EDT Weak oil and copper prices and disappointing earnings have taken their toll, says Phil van Doorn. Read More >> Related Stocks: Allergan Plc Biogen Idec Capital One Financial Caterpillar Chesapeake Energy Freeport-McMoRan Frontier Communications Lockheed Martin Mylan Standard & Poors 500 Teva Pharmaceutical Industries ADR TripAdvisor United Rentals United Technologies