Citigroup Incorporated said Monday its first-quarter net profit rose 4 percent, as a smaller loss on its troubled assets more than offset a drop in revenue and profit from its core trading and lending businesses. The third-largest U.S. bank said profit rose to $4.15 billion in the January-March period, up from $4 billion in the same quarter a year ago. Revenue was $20.12 billion, down 2 percent from $20.6 billion a year earlier. Both profit and revenue figures beat Wall Street estimates. Despite the better-than-expected results, the report Monday capped a disappointing quarter for the bank, which last month failed to win regulatory approval to pay a higher dividend and return $6.4 billion of capital to shareholders through stock buybacks. Citigroup chief executive Mike Corbat is struggling to meet expectations set when he was appointed in October 2012 that Citigroup raise its profitability to industry standards and improve its relationships with regulators.