Citigroup reports profit drop, sees more pain if oil slips

Citigroup Inc's quarterly profit plunged 27 percent, dragged down by lower revenue from trading and investment banking as well as costs to shrink some businesses and cover bad loans to the energy industry. Citigroup has reported the biggest drop in profit among big U.S. banks that have released first-quarter results so far, but lower operating expenses helped the bank beat Wall Street's low expectations. Citigroup's shares rose as much as 3.5 percent in morning trading.