Citi analyst Eric Petrie upgraded Trinseo to Buy from Neutral with an unchanged price target of $58. The analyst sees a favorable risk/reward following the recent pullback in the shares. The "knee-jerk" reaction to an initial investigation for potential violation of antitrust rules into styrene purchasing activity by the European Commission that could result in assessed fines is likely overdone, Petrie tells investors in a research note. The analyst says his basic fine estimate range of $135M-$180M is below investors' worst-case scenario at 10% of overall sales and that his assumptions could prove to be aggressive.