Quest Diagnostics downgraded to Underperform from Market Perform at Wells Fargo Wells Fargo downgraded Quest Diagnostics (DGX) to its sell-equivalent Underperform rating saying the charges associated with the company's Invigorate savings initiative should not be viewed as one-time by investors. Wells thinks the initiative will need to be ongoing as Quest's margins are declining. It keeps a $60-$65 price target range for shares. The diagnostic testing company closed yesterday up 52c to $71.09. Quest’s main competitor is LabCorp (LH).