(Reuters) - Morgan Stanley's quarterly earnings rose as the bank's legal costs fell sharply, outweighing a big drop in revenue from its division that trades bonds, currencies and commodities.Choppy markets caused by factors ranging from plunging oil prices to political upheaval in Greece, sent investors scurrying last month, slashing the trading revenue of U.S. banks including Morgan Stanley arch rival Goldman Sachs Group Inc.Morgan Stanley said on Tuesday that its revenue from trading fixed-income securities, currencies and commodities (FICC) fell 81 percent to $133 million, excluding accounting adjustments.Revenue from the bank's increasingly important wealth management business rose 2.4 percent to $3.80 billion as equity markets boomed.Overall, earnings attributable to common shareholders rose to $920 million, or 47 cents per share, in the fourth quarter from $36 million, or 2 cents per share, a year earlier.Legal expenses fell to $284 million from $1.4 billion.(Reporting by Tanya Agrawal and Lauren Tara LaCapra; Editing by Ted Kerr)Join the conversation about this story »