The big keep getting bigger — at least when it comes to gathering deposits.

According to new market share data released by the Federal Deposit Insurance Corp. Tuesday, banks and thrifts with $10 billion or more of assets controlled 72% of the nation's bank deposits at June 30, up from 70% at the same time last year and 68.5% in 2008.

At the same time, total deposits at banks in eight of the FDIC's nine other asset classes declined year over year. Only banks in the $1 billion- to $3 billion-asset category posted deposit gains, according to the latest data.

Industry experts have cited a range of reasons for why consumers and businesses are parking their deposits at large banks, the most notable being the perception that regulators would not allow these banks to fail.

Despite paying historically low interest rates, banks are also seen as safe havens from the volatile stock and bond markets. Overall, total deposits at the nation's banks increased 7.4% year over year, to $8.2 trillion at June 30.

The largest bank holding company by deposits — by far — remains Bank of America Corp., which this year became the first bank ever to top the $1 trillion mark, even though it shed nearly 200 branches year over year.

Wells Fargo & Co. has 550 more branches than B of A, but it ranked a distant second with $793.6 billion of deposits. As in 2010, JPMorgan Chase & Co. ranked third and Citigroup Inc. ranked fourth.

The big mover in this year's rankings was U.S. Bancorp, which leapfrogged over PNC Financial Services Group Inc. into fifth place. At June 30, the Minneapolis company had $198.5 billion of deposits, an increase of 17% from the same time a year earlier.

U.S. Bancorp can attribute the surge of deposits in part to the expansion of its branch network. The company added 89 branches between July 1, 2010 and June 30, 2011.

Industry wide, though, the number of branches continues to shrink; at June 30, U.S. banks and thrifts had a total of 98,201 branches, or almost 1,000 fewer than they had at their historic peak in mid-2008.

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