Federal Deposit Insurance Corp. (FDIC) regulators closed four banks last Friday, bringing this year's national tally of failed banks to 84.

Community Banks of Colorado became the latest casualty, bringing the count in that state to six this year. In addition, Community Capital Bank and Decatur First Bank located in the state of Georgia, and Old Harbor Bank in the state of Florida were also closed.

As of June 30, Community Banks of Colorado had approximately $1.38 billion in total assets and $1.33 billion in total deposits. The estimated cost to the Deposit Insurance Fund, which includes liquidating assets and ensuring funds, among others, stands at $224.9 million. The other three institutions are estimated to cost the fund about $133.9 million.

The largest number of bank closures in the last four years have taken place in Georgia, where 73 institutions ended operations, according to an analysis by CNBC.com. Florida is next in line, with 54 bank failures, followed by Illinois with 45.

Since 2008, a total of 406 banks have collapsed in the U.S.

The majority of failures took place in 2010, with 157 banks closing their doors that year.

In a quarterly report back in August, the FDIC said that the number of banks classified as troubled has declined for the first time in almost five years to 865 at the end of June from 888 in April.

The number of institutions on the "problem list" accounted for about 11 percent of the nation's banks.

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