Stock buybacks boost returns — but often cover up sins By: MarketWatch November 19, 2014 at 06:00 AM EST S&P 500 companies with the biggest buybacks have tended to underperform this year, writes Phil van Doorn. Read More >> Related Stocks: ADT Corp Apple Bed Bath & Beyond CBS Corp CF Industries Holdings Cameron International Citrix Systems Hess Corp Illinois Tool Works International Business Machines Juniper Networks Standard & Poors 500 Viacom