First, lower rates will prompt homeowners to refinance, increasing prepayment speeds and lowering the value of the underlying bonds.

FORBES: Surprise! Junk Debt Is Coming Back Into Style

Every time it looks as if the government might push for British entry, the pound weakens, with currency traders reckoning that a decision to go in would prompt the government actively to try to depress the pound's value ahead of entry.

ECONOMIST: Further to fall? | The

There are fears that if the value of Bankia's shares were wiped out in the rescue, this could prompt such anxiety among savers that they could withdraw their savings from Bankia, further weakening the bank.

BBC: Will Spain suffer an Irish bust?