So much for the green shoots and improving tone for America’s banks.

Three more US banks were shut down Friday, bringing the total number of failures so far this year to 32. At the same time a big non-bank mortgage provider finally went belly up, over a year after first reporting trouble with debt of $US24 billion.

The total now comfortably exceeds the 25 banks which failed last year, though not in size or impact.

One of the failed banks was not a retail operator, but a wholesale bank, which served 1,400 other banks across the US. The two other banks were smaller regional operators in New Jersey and Utah.

Silverton Bank, National Association, headquartered in Atlanta, did not take deposits directly from the general public or make loans to consumers. Instead, it was a “bankers’ bank,” offering a wide variety of services, such as foreign cash wire transfers, as well as clearing and cash management, to 1,400 other smaller banks.

At the time of its closing, Silverton Bank had approximately $4.1 billion in assets and $3.3 billion in deposits, all of which are expected to be within the FDIC’s insurance limits. It was the 5th biggest US bank to fail in the current crisis and the largest so far this year.

It’s yet another sign of the fragility of small and medium financial groups in the US. Several credit unions and credit union banks (similar to Silverton which cleared and provided other services) have failed and been taken over by regulators.

Friday’s failure of Thornburg Mortgage Inc , a provider of so-called jumbo mortgage loans (large housing loans too big to be insured) filed for Chapter 11 bankruptcy protection and said it plans to wind down and sell off key units.

The company is one of the largest casualties yet of the U.S. housing slump and credit crisis. It has been struggling for over a year to keep afloat but finally threw in the towel late last week. In its court filing it listed total assets of $US24.4 billion and total debts of $US24.7 billion.

The Federal Deposit Insurance Corp said in a statement that it created a bridge bank to take over the operations of Silverton that was cooperatively owned by community banks throughout the Southeast of the US and heavily invested in loans to real estate in Florida, Georgia, and other states across the region, all of which have been hit heavily by the subprime collapse and the associated housing and commercial property slump.

The FDIC estimates that the cost to the Deposit Insurance Fund will be $US1.3 billion, making it the fourth costliest bank failure since the start of the recession.

Silverton’s clients and customers are other banks, who will have to find someone else to cover the services it offered: the FDIC will only carry the load for a maximum of 90 days and beyond that some of the banks might struggle to find a clearer and service provider, putting their existence in doubt.

Regulators also shut down Citizens Community Bank in New Jersey on Friday night, and later in the night revealed that a small local bank in Utah had been shut. The America West bank in Layton was closed and a nearby bank took over its business.

Nearly every Friday so far this year, at least one bank has failed. Last week, four regional banks were shut.

The steady rate of failure belies all the attention being directed at the trials and self inflicted tribulations of the big money centre banks, the Citigroup’s and Bank of America’s, not to mention the greedy and poorly run former investment banks.

This week will see the airwaves dominated by leaks and news about the stress tests of the 19 biggest US banks: the thousands of smaller banks are basket cases, it seems, more and more, just waiting to implode on any given Friday.