Net interest margin

Higher net interest income and securities gains boosted quarterly profit to $62.6 billion, which was 4% higher from a year earlier. But potential trouble signs from lower interest rates may emerge.

With long-term interest rates at historic lows, mortgage refinancing is coming on strong. But that additional revenue may not be enough to offset net interest margin pressures and lost servicing income.

Lenders insist they will be able to ramp up commercial loans and mortgage refinancings without skimping on underwriting.

M&T Bank, Zions and Comerica are among the regional banks facing the most pressure on net interest margins, Wells Fargo analysts said in a research note to investors.

With long-term interest rates at historic lows, mortgage refinancing is coming on strong. But that additional revenue may not be enough to offset net interest margin pressures and lost servicing income.

Readers react to the Fed's lengthy plan for a real-time payments system and Fifth Third's minimum wage increase, jab at Sen. Warren's absence on the Senate Banking Committee and more.

Lenders could struggle to reprice deposits fast enough to offset downward pressure from adjustable-rate loans and refinancing.

China's decision to stop buying U.S. soybeans and let its currency depreciate raised the prospect of further interest rate cuts. That hurt banks slightly more than the rest of the market on what was a bad day for all equities.

These banks posted strong quarterly results at a time when many others struggled with thinner margins and rising expenses.

Earnings at the U.S. unit of the Spanish banking giant Banco Bilbao Vizcaya Argentaria fell 13% from a year earlier.