From The Christian Science Monitor:

Does the US banking system, still recovering from the financial crisis that roiled Wall Street two years ago, face a new emergency?

The Obama administration says no, at least for now. But the words "systemic risk" are being heard again in congressional meeting rooms, just months after President Obama signed a law designed to head off future crises on Wall Street.

The reason is that an uproar over faulty paperwork in the mortgage business may spawn a boom in lawsuits against big banks.

The problem isn't large enough to jeopardize the survival of big banks, many finance experts say. On Wednesday, a US Treasury official voiced a similar view.

"At this time, there is no evidence that there is a systemic risk to the financial system," Phyllis Caldwell, the Treasury's chief of homeownership preservation, told the Congressional Oversight Panel in a hearing focused on the Obama administration's mortgage policies.

The problem is, it's hard to know for sure how exposed the banks are.