Stephen Hester, chief executive of the Royal Bank of Scotland, speaking on the Today programme, urges markets to be "calm" in face of turmoil:
"We are seeing today what arguably we should have seen in 2008.
"It's not a banking crisis. It's never was. It's one of global economic imbalances. We are seeing that coming back more clearly.
"We need to focus on being calm in the face of all this news and be purposeful."