Signature Bank is the second casualty of the ongoing banking crisis in the U.S. The New York-based financial institution stopped operating abruptly on Sunday — customers will be made whole. Regulators said that Signature Bank also caused a systemic risk and could threaten the U.S. banking system. “We are also announcing a similar systemic risk exception for Signature Bank, New York, New York, which was closed today by its state chartering authority,” the U.S. Treasury Department, the FDIC and the Federal Reserve said in a joint statement.