One of the bright spots in Citigroup Inc.’s turnaround strategy is starting to lose a little luster.
For years, the New York-based bank C, -0.25% has steadily grown its card business, boosting loans and investing heavily despite problems elsewhere that ranged from headaches in Mexico to regulatory problems that lingered after the financial crisis.
But now, some cracks in the card business have emerged, raising questions just as CEO Michael Corbat has shored up the bank’s other issues.
