WASHINGTON: Regulators on Friday shut down Colonial BancGroup Inc., a lender in real estate development, in the biggest U.S. bank failure this year, and also closed four banks in Arizona, Nevada and Pennsylvania.

The closures boosted to 77 the number of federally insured banks that have failed in 2009.

The Federal Deposit Insurance Corp. was appointed receiver of the banks: Montgomery, Ala.-based Colonial, with about $25 billion in assets; Community Bank of Arizona, based in Phoenix; Union Bank, based in Gilbert, Ariz.; Community Bank of Nevada, based in Las Vegas; and Dwelling House Savings and Loan Association, located in Pittsburgh.

The FDIC approved the sale of Colonial's $20 billion in deposits and about $22 billion of its assets to BB&T Corp., which is based in Winston-Salem, N.C. The failed bank's 346 branches in Alabama, Florida, Georgia, Nevada and Texas will reopen at the normal times starting on Saturday as offices of BB&T, the FDIC said.

The agency established a temporary government bank for Community Bank of Nevada to give depositors about 30 days to open accounts at other financial institutions. The failed bank had assets of $1.52 billion and deposits of $1.38 billion as of June 30.

Community Bank of Arizona had assets of $158.5 million and deposits of $143.8 million as of June 30, while Union Bank had assets of $124 million and deposits of $112 million as of June 12. The FDIC said that MidFirst Bank, based in Oklahoma City, has agreed to assume all the deposits and $125.5 million of the assets of Community Bank of Arizona, as well as about $24 million of the deposits and $11 million of the assets of Union Bank. The FDIC will retain the rest for eventual sale.

Dwelling House had $13.4 million in assets and $13.8 million in deposits as of March 31. PNC Bank, part of Pittsburgh-based PNC Financial Services Group Inc., has agreed to assume all of Dwelling House's deposits and about $3 million of its assets; the FDIC will retain the rest for eventual sale.

The failure of Colonial is expected to cost the deposit insurance fund an estimated $2.8 billion.

The 77 bank failures nationwide this year compare with 25 last year and three in 2007.

As the economy has soured with unemployment rising, home prices tumbling and loan defaults soaring bank failures have cascaded and sapped billions out of the deposit insurance fund. It now stands at its lowest level since 1993, $13 billion as of the first quarter.

While losses on home mortgages may be leveling off, delinquencies on commercial real estate loans remain a hot spot of potential trouble, FDIC officials say. If the recession deepens, defaults on the high-risk loans could spike. Many regional banks hold large numbers of them.

The number of banks on the FDIC's list of problem institutions leaped to 305 in the first quarter the highest number since 1994 during the savings and loan crisis from 252 in the fourth quarter. The FDIC expects U.S. bank failures to cost the insurance fund around $70 billion through 2013.

The May closing of struggling Florida thrift BankUnited FSB is expected to cost the insurance fund $4.9 billion, the second-largest hit since the financial crisis began. The costliest was the July 2008 seizure of big California lender IndyMac Bank, on which the insurance fund is estimated to have lost $10.7 billion.

The largest U.S. bank failure ever also came last year: Seattle-based thrift Washington Mutual Inc. fell in September, with about $307 billion in assets. It was acquired by JPMorgan Chase & Co. for $1.9 billion in a deal brokered by the FDIC.