The number of U.S. lenders that cannot collect on at least 20% of their loans has hit an 18-year high, according to Federal Deposit Insurance Corp. data compiled by SNL Financial, a bank research firm.

It said 26 companies had more than one-fifth of their loans 90 days overdue or not accruing interest as of June 30 — a level of distress almost five times the national average.

Though regulators may not force companies on the list to close, just requiring them to raise capital and curb lending may impede recovery in Florida, Illinois and seven other states. The banking companies are among the most vulnerable of a larger group of lenders whose failures the FDIC said could cost $100 billion by 2013.

"There are some zombie banks out there," said Bert Ely, a bank consultant in Alexandria, Va. "Neither the banking industry nor the economy benefits from keeping weak banks in business."

As of Friday afternoon, 95 banks had failed this year, the fastest pace in almost two decades, depleting the FDIC's insurance fund. The agency proposed on Sept. 29 that financial companies prepay three years of premiums, which would add $45 billion of reserves. The fund sank to $10.4 billion at June 30, its lowest balance since 1993. It will run at a deficit starting this quarter, the FDIC said.

The cost of this year's failures to the FDIC equals 25% of the banks' assets, according to agency data. Applying the same ratio to the $14.1 billion of assets held by the 26 lenders on SNL's list would mean that the FDIC could face $3.5 billion of additional losses.

Noncurrent loans averaged 4.35% of U.S. banks' total at June 30, the most in 26 years of FDIC data. Regulators typically take notice at 5%, according to Walter Mix, a former commissioner of the California Department of Financial Institutions. Corus Bankshares Inc.'s bank unit in Chicago was shut Sept. 11 after 71% of its loans soured.

The last time so many banks had 20% of their loans more than 90 days overdue was in 1991, near the end of the savings-and-loan crisis, when there were 60, according to an SNL analysis of FDIC data. That year the number of bank failures was less than half those at the peak of the crisis in 1988; this year failures are almost four times what they were in 2008.

For banks with 20% of loans overdue, "either they've got a massive amount of capital, or the FDIC just hasn't gotten around to them," said Jeff Davis, an analyst at First Horizon National Corp.'s FTN Equity Capital Markets in Nashville. Lack of staff and money are slowing shutdowns, he said.

At least 17 of the 26 banking companies have been hit with civil penalties or enforcement orders that demand improved management and more capital, according to data compiled by Bloomberg.

Regulators may be pacing themselves on closings because the FDIC fund "is only so big" and there is not enough staff to close all the struggling banks at once, said Kevin Fitzsimmons, a managing director at Sandler O'Neill & Partners LP, a New York brokerage firm specializing in banks. Also, customers are not staging mass withdrawals that would force action.

Though a high level of nonperforming assets does not mean a bank cannot survive, "in some cases it creates a hole that's too deep to climb out of," he said.

Subscribe Now

Access to authoritative analysis and perspective and our data-driven report series.

14-Day Free Trial

No credit card required. Complete access to articles, breaking news and industry data.