Quote from Martinghoul:
I have no beef whatsoever in this discussion, but I do try to respond to questions about the housing crisis whenever I can, in order to prevent politics from clouding the issue any further. So here goes...
This is incorrect and there's a variety of evidence to prove it.
Allow me to add: mortage issuance was not a core commercial banking function at all back when I had hair. It only recently became a big business for them, and my guess as to why is a combination of the S&L industry going bye-bye and companies funding themselves increasingly through issuing bonds rather than through commercial loans.
Regardless, mortgages are known to have all kinds of crazy risks. They all stem from this: you're issuing, in effect, in the US, a 30 year bond that is callable at any time. If you want to see how hard it is to make money from such craziness, try it some time.