A sharp turnaround by the two biggest banks in the mortgage banking business led to a significant increase in aggregate mortgage banking income reported by commercial banks in the first quarter. A new Inside Mortgage Trends analysis and ranking reveals that banks reported a combined $4.215 billion in noninterest income on their mortgage banking activities during the first quarter of 2011. That was up 20.8 percent from the industry’s $3.488 billion in mortgage banking income during the fourth quarter of 2010. But in the top-heavy mortgage banking market, the results were skewed dramatically by the performance of... [Includes one data chart]