Barry Ritholtz emails to say that he disagrees with Paul Krugman's about the importance of lack of regulation in the subprime market in explaining the crisis:
Bubbles & Banks & Zero Lending Standard Loans, by Barry Ritholtz: Paul Krugman has an interesting OpEd in today's NYT, one that I mostly agree with.
However, I take exception to his perspective on a few issues, one of which might ultimately prove to be crucial to understanding the crisis and putting the correct financial reform measures in place. ... The ... disagreement is over the impact of sub-prime loans on the entire US Housing market, and whether lending standards can be adequately enforced. Had then Fed Chairman Alan Greenspan done his job properly, and prevented Zero Lending Standard loans from infecting the real estate market, we would have been looking at a very different housing situation -- to the upside as well as to the down side.