The government-administered insurance fund that protects depositors fell into the red for the first time since the fallout from the savings-and-loan crisis of the early 1990s as the pace of bank failures accelerated.

The fund had a negative balance of $8.2 billion at the end of the third quarter, federal regulators said Tuesday. Bank customers, however, should remain confident that their deposits would be protected since most of the amount reflects money that Federal Insurance Deposit Corporation has already set aside to cover the losses from future bank failures.

Officials of the F.D.I.C. said in October that the deposit insurance fund had been depleted, but the third-quarter report card on the banking industry issued on Tuesday was the first time that hard numbers had been released. Even amid early signs that the economy is recovering, the report suggested that the country’s 8,100 lenders remain in fragile condition.

In its state of the industry report, the F.D.I.C. reported that banks posted a $2.8 billion gain in the third quarter, after a $4.3 billion loss in the previous period. Meanwhile, the number of “problem banks” that run the biggest risk of collapse increased to 552, from 416 in the second quarter. The number of bad loans of nearly every stripe  credit cards, mortgages, small business and commercial real estate  continue to grow, albeit at a slower pace.