The insurance fund is in better shape than such numbers might suggest, however. Officials estimate that bank failures would drain about $100 billion from the fund from 2009 through 2013. But of that amount, a total of roughly $80 billion in losses were recognized last year or projected for 2010. By that math, the agency is expecting an additional $20 billion of losses over the next three years.

After slipping into the red last fall, the F.D.I.C. moved swiftly to refill its coffers. The agency imposed a special assessment on banks that gave it an immediate $5.6 billion cash infusion. That assessment was in addition to the ordinary payments that banks make to the F.D.I.C. fund.

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In September, the F.D.I.C. ordered banks to prepay quarterly assessments that would have otherwise been due through 2012. That provided an additional $46 billion to restore the fund to normal. For accounting purposes, the agency will add that money to the fund in small doses over the next 13 quarters, which explains the current negative balance.

Together, these moves buy time for the agency to determine its next steps in the event its losses worsen. In such a case, banks might be called on to chip in more money, either through new special assessments, prepaid fees or premium increases. F.D.I.C. officials said no such plans were in the works.

“The good news is that the industry will power through this,” said Bert Ely, a longtime banking industry consultant in Washington. The fund has “taken a lot of hits along the way, but I still don’t expect the taxpayer to ride to the rescue.”

To protect the fund, the F.D.I.C. also has found creative ways to bring in more money. On Tuesday, Ms. Bair said that the agency would soon issue bonds backed by the assets of failed banks and guaranteed by the government. The program aims to attract nontraditional buyers of bank assets, like insurance companies, pension funds and mutual funds.