[Book authors Mian and Sufi] argue that, rather than failing banks, the key culprits in the financial crisis were overly indebted households. Resurrecting arguments that go back at least to Irving Fisher and that were emphasised by Richard Koo in considering Japan’s stagnation, Mian and Sufi highlight how harsh leverage and debt can be ”“ for example, when the price of a house purchased with a 10 per cent downpayment goes down by 10 per cent, all of the owner’s equity is lost. They demonstrate powerfully that spending fell much more in parts of the country where house prices fell fastest and where the most mortgage debt was attached to homes. So their story of the crisis blames excessive mortgage lending, which first inflated bubbles in the housing market and then left households with unmanageable debt burdens. These burdens in turn led to spending reductions and created an adverse economic and financial spiral that ultimately led financial institutions to the brink.
This interpretation resolves the anomalies that Mian and Sufi highlight. Households do not spend while they are still overly indebted, which precipitates slow growth even after banking is restored to health. Spending slowdowns are caused by household over-indebtedness, so of course they precede problems in the banking system. And, when consumers do not spend, businesses have less need to borrow to finance investment, inventories or receivables.
Their analysis, presented with far more depth and subtlety than I have been able to reflect here, is a major contribution that furthers our understanding of the crisis. It certainly affects what I will examine in trying to predict and forestall future crises. And it should influence policies aimed at crisis prevention by demonstrating the insufficiency of keeping financial institutions healthy and by making a case for macroprudential measures directed at preventing runaway growth in household debt.
Read it all (my emphasis).