Wells and JPMorgan are bellwethers for mortgages. Wells controls a third of the market, according to the trade publication Inside Mortgage Finance. JPMorgan is second, controlling about 11 percent.
Both banks cited low interest rates to help explain the boost in refinancing, though it wasn't clear why this quarter was so strong. Rates have been low for several years.
The average interest rate on a 30-year fixed mortgage is 3.47 percent, according to the government-sponsored mortgage giant Freddie Mac. It's been under 4 percent for almost a year.
There are still plenty of homeowners who can't afford their mortgages, a point that Dimon was quick to note. He said his bank is still seeing a high level of souring mortgage loans, and said he expects high default-related expenses "for a while longer."
Stumpf acknowledged that the housing market is still "not back to where we need to be, and it is not as robust as we would all want it to be."
Shoddy lending standards helped cause the 2008 financial crisis, and both banks are still dealing with the hangover.
Last week, the New York attorney general sued JPMorgan over the risky mortgage-backed securities once peddled by Bear Stearns, which JPMorgan later bought. JPMorgan says it will contest the charges.
This week, the federal government sued Wells Fargo, charging that the bank improperly received millions of dollars' worth of government insurance payouts for failed mortgage loans. Wells Fargo denies the charges, and says that it has already settled many of the issues raised in the lawsuit with the government.
Both banks are also still dealing with demands from investors that they buy back mortgages they sold in the run-up to the financial crisis.
Some highlights from both banks' earnings reports:
-- JPMorgan: The bank made $5.3 billion in the third quarter, up 36 percent from the same period a year ago. It worked out to $1.40 per share, blowing away the $1.21 predicted by analysts polled by FactSet, a provider of financial data.
Revenue rose 6 percent to $25.9 billion, beating expectations of $24.4 billion. Besides the higher mortgage revenue, the bank also set aside less money for bad loans, trimmed expenses, and enjoyed higher credit card use and investment banking fees.
-- Wells Fargo: Wells made $4.7 billion in the third quarter, up 23 percent from the same period a year ago. That amounted to 88 cents per share, a penny higher than estimates. Overall revenue rose 8 percent to $21.2 billion, slightly lower than analysts expected.
JPMorgan's stock fell about 1 percent, losing 48 cents to $41.62, although it fared much better than other financial stocks. Wells Fargo's stock fell more than 2 percent, losing 93 cents to $34.25.