May 21 (Bloomberg) -- BankUnited Financial Corp., the ailing Florida lender, was shut by federal regulators and its assets were sold to private-equity firms including WL Ross & Co. and Carlyle Group in the largest U.S. bank failure this year.

The group’s purchase of the bank, deemed “critically undercapitalized” by the Office of Thrift Supervision, was the “least costly” resolution, the Federal Deposit Insurance Corp. said today in a statement. The closing will cost the insurance fund $4.9 billion, pushing the total cost of 34 seizures so far this year to more than $10 billion.

BankUnited, based in Coral Gables with 86 branches on Florida’s southeast coast, will open tomorrow under an ownership group that includes Blackstone Group LP and Centerbridge Capital Partners LLC and will be led former North Fork Bancorp Chief Executive Officer John Kanas, 62, the FDIC said.

“The unusual thing here is you have John Kanas involved, and just given his background I’m sure it gave regulators comfort,” said Gary Townsend, CEO of Hill-Townsend Capital LLC, a Chevy Chase, Maryland-based manager of hedge funds focused on the banking industry. “His background is pretty unique.”

BankUnited, with $8.6 billion of deposits and $12.8 billion in assets, is the second lender sold to private-equity investors this year, underscoring the eagerness of such companies to buy financial firms after global losses from the credit crisis topped $1.4 trillion. The FDIC in January approved selling IndyMac Bank, which was seized in July, to private-equity investors led by Steven Mnuchin, a former executive at Goldman Sachs Group Inc., and including buyout firm J.C. Flowers & Co.

“It is a lot like the IndyMac sale except the FDIC found a buyer right away,” said Bert Ely, a banking consultant in Alexandria, Virginia.

FDIC ‘Evaluating’ Investments

The FDIC in November announced plans to let investors or groups lacking a bank charter bid for deposits and assets of failing lenders, a step the agency at the time said would permit marketing of lender assets to non-bank bidders.

“Due to the interest of private equity firms in the purchase of depository institutions in receivership, the FDIC has been evaluating the appropriate terms for such investments,” the agency said in its statement. “In the near future, the FDIC will provide generally applicable policy guidance on eligibility and other terms and conditions for such investments to guide potential investors.”

BankUnited was in an “unsafe condition” and the quality of its loan portfolio had deteriorated, said the OTS, the lender’s main regulator. The agency in mid April ordered the company to find a buyer, or sell itself within two weeks.

Loans Portfolio

Residential home mortgages were $9.6 billion, or 73 percent of all assets, and nonresidential mortgage loans were $580.3 million, or 4.4 percent, the agency said. Brokered deposits were $460.4 million, or 3.5 percent of liabilities, OTS said.

BankUnited’s fiscal second-quarter loss probably rose to $443.1 million, or $12.55 a share, from a loss of $65.8 million, or $1.88, a year earlier, the company said in a May 12 regulatory filing. Loans no longer collecting interest rose to 18 percent of total loans from 14 percent in December.

The FDIC deposit fund is down 64 percent from its peak at the start of the second quarter last year, reflecting the shutdown of 22 lenders from April through December. Costs from closing banks in the second quarter climbed to $8 billion, including $4.9 billion for BankUnited, from $2.28 billion in the first quarter, FDIC data show.

The FDIC has proposed an emergency fee of 20 cents per $100 in insured deposits to replenish the fund, a decision the agency will make tomorrow. FDIC Chairman Sheila Bair has said raising the agency’s line of credit with Treasury to $100 billion from $30 billion could help reduce the size of the levy.

To contact the reporters on this story: Jonathan Keehner in New York at jkeehner@bloomberg.net.

Last Updated: May 21, 2009 19:14 EDT