Bankers push back against any notion of oligopoly.
"The mortgage business is extraordinarily competitive," said Franklin Codel, head of mortgage production at Wells Fargo Home Mortgage.
There are other factors at work. For one thing, fees charged to lenders by government-controlled mortgage-finance companies Fannie Mae and Freddie Mac are set to rise this year. The increases paid for the payroll-tax break passed by Congress in December.
Analysts stress it is difficult to disentangle how much of the spread is due to pricing power from banks with more control of the market, and how much might represent structurally higher costs of doing business in the U.S. mortgage market reshaped by the crisis.