FDIC reveals the extraordinary amount of 'unrealized losses' across U.S. banks amid fears more will collapse after the sudden failure of SVB and Signature

Banks across America are sitting on $620 billion of 'unrealized losses' - assets which have decreased in value but have not yet been sold - - the head of the Federal Deposit Insurance Corporation warned.

News of the worrying shortfall came amid the closure of Silicon Valley Bank - the largest collapse since Washington Mutual in 2008.

As the government scrambles to prevent contagion, the Federal Reserve announced on Sunday night that all depositors would get their money back.