LOS ANGELES ‚?? Wells Fargo & Co. on Tuesday reported a 20 percent jump in fourth-quarter profit, with better-than-expected returns from its giant mortgage business, while Citigroup earnings declined 11 percent on weakness in its investment bank operations. The results underscored how the turbulent financial markets have affected banks with big Wall Street sales and trading operations, such as Citi. JPMorgan Chase & Co., the nation‚??s largest bank as measured by assets and another huge Wall Street player, kicked off the bank earnings season last week by reporting a 23 percent decline in profit, with investment banking revenue down 30 percent. Wells Fargo, by contrast, is more focused on consumer businesses. It showed that it is working through the problems in its mortgage business, the nation‚??s largest with a 30 percent market share, as nonperforming assets fell 20 percent and its provision for future loan losses declined. The San Francisco-based company, California‚??s largest bank and the fourth-largest nationally, said revenue from community banking, which includes branches and mortgages, was up 30 percent year over year. Analysts at Keefe Bruyette & Woods said Wells Fargo‚??s profit margin on lending beat their expectations and those of Wall Street overall, "and mortgage banking was much stronger (than expected)." Citigroup, the third-largest U.S. bank as measured by assets, also reported improving credit quality, but said its capital-markets business, which includes sales and trading on Wall Street, saw its revenue decline by 10 percent. Wells Fargo earned $4.1 billion in the fourth quarter, or 73 cents per share, up from $3.4 billion, 61 cents per share, a year earlier. Revenue fell from $21.5 billion to $20.6 billion. Citigroup reported a profit of $1.16 billion, 38 cents a share, compared with $1.31 billion, 43 cents a share, in the fourth quarter of 2010. Revenue fell from $18.4 billion to $17.2 billion.