Oct.'s surprise resignation of CEO Vikram Pandit and his replacement by Michael Corbat was called a "game-changer" for the No. 3 U.S. bank by a Sterne Agee analyst. The firm upgraded Citigroup (NYSE:C) to buy from neutral. While Europe remains a trouble spot, a recent upgrade in Greek debt and general improving macro situation bode well for Citi. The analyst raised his '13 EPS estimate to $4.80 from $4.45 and his '14 EPS estimate to $5.40 from $5. Shares rose 0.3% to 41.39, hitting a new 52-week high.