What was it that Donald Rumsfeld famously said? "There are known knowns, the things we know we know. There are known unknowns, things we know we don't know. And then there are the unknown unknowns, the ones we don't know we don't know."
Anyone working in the credit markets today probably understands what the US secretary of defence meant.
Investors have known for some time that a downgrade for General Motors was inevitable, and that Ford would probably go with...
