The FDIC also said that federally-insured banks and savings institutions earned $5 billion in the April-June period, down from $36.8 billion a year earlier. The roughly 8,500 banks and thrifts also set aside a record $50.2 billion to cover losses from soured mortgages and other loans in the second quarter.
"Quite frankly, the results were pretty dismal," FDIC Chairman Sheila Bair said at a news conference, but they were not surprising given the housing slump, a worsening economy, and disruptions in financial and credit markets.
The majority of U.S. banks "will be able to weather" the economic and housing storms, with 98 percent of them still holding adequate capital by the regulators' standards, Bair said.
Total assets of troubled banks jumped from $26 billion to $78 billion in the second quarter, the FDIC said, with $32 billion of the increase coming from IndyMac Bank, which failed in July - the biggest regulated thrift to fail in the United States.
"More banks will come on the (troubled) list as credit problems worsen," Bair said. "Assets of problem institutions also will continue to rise."
Nine FDIC-insured banks have failed so far this year, compared with three in all of 2007. More banks are in danger of collapsing this year, Bair and other FDIC officials said, and they expect turbulence in the banking industry to continue well into next year.
IndyMac's failure and others in the quarter reduced the federal deposit insurance fund from $53 billion to $45 billion. Bair said the agency will raise insurance premiums paid by banks and thrifts to replenish its reserve fund and bolster depositors' confidence.
The $50.2 billion set aside to cover loan losses in the April-June period was four times the $11.4 billion the banking industry salted away a year earlier. Nearly a third of the industry's net operating revenue went into building up reserves against losses in the latest quarter, according to the FDIC.
Except for the fourth quarter of 2007, the earnings reported Tuesday were the lowest for the banking industry since the final quarter of 1991, the agency said.
Concern has been growing over the solvency of some banks amid the housing slump and the steep slide in the mortgage market. The pressures of tighter credit, tumbling home prices and rising foreclosures have been battering banks of all sizes nationwide.
The FDIC has been keeping an especially close eye on banks and thrifts with high levels of exposure to the riskiest borrowers and markets, agency officials say, including subprime mortgages and construction loans in overbuilt areas.
Another area of potential concern: banks' holdings of preferred stock of troubled mortgage giants Fannie Mae and Freddie Mac. A government rescue of the companies, whose share prices have rebounded a bit this week after plummeting recently as they struggle with billions of dollars in losses from bad mortgages, could be costly for scores of banks that hold billions in their preferred shares.
"We're closely monitoring that situation," Bair said.
The FDIC said troubled assets - loans that are 90 or more days past due - continued to rise in the second quarter, jumping by $26.7 billion, or 19.6 percent, over the first quarter. It was the first time since 1993 that the percentage of total loans that were troubled broke 2 percent, at 2.04 percent.
The agency doesn't disclose the names of institutions on its internal list of troubled banks. On average, 13 percent of banks that make the list fail.
Pasadena, Calif.-based IndyMac was taken over by the FDIC on July 11 with about $32 billion in assets and deposits of $19 billion. It was the second-largest financial institution to close in U.S. history, after Continental Illinois National Bank in 1984.