Quest, LabCorp Among S&P 500's Top Gainers After Upgrades

Quest Diagonostics Inc. and Laboratory Corp. of America Holdings -- two medical-testing companies -- were among the S&P 500's biggest gainers on Friday after upgrades from Raymond James analysts, rising 1.7% and 3.3%, respectively. The analysts lifted Quest to market perform from underperform, saying they still have "reservations concerning the industry's long-term prospects," but they "see better growth in 2015 and 2016 as certain headwinds abate." Raymond James hiked LabCorp to outperform from underperform, citing benefits from the company's cost cuts and its Covance acquisition.