Almost five years after the worst throes of the financial crisis, the biggest US banks face a widening array of legal challenges.

The US Department of Justice this month filed civil charges against Bank of America alleging it defrauded investors when selling mortgage-backed debt in 2008. JP Morgan indicated in its most recent securities filing that it is also facing government scrutiny related to sales of such securities, even as it continues to grapple with multiple inquiries into its "London Whale" trading debacle.