LAST November, the American publisher of those yellow books that claim to help "dummies" master everything from trigonometry to anger management released Flipping Houses for Dummies. It promised to teach would-be property moguls how to "lay the foundation for successful flipping and bring home the bucks."

Lenders, intent on keeping fees flowing as the housing market began to cool in 2004, pulled a swath of Main Street America into the housing market. They lowered standards and offered a bevy of "affordability" products like extra-, long-term or "interest-only" mortgages (in which principal payments are deferred for a time) and loans with low teaser interest rates that balloon after a few years.

Others are scrutinizing "Alt A" mortgages, underwritten with little or no documentation of, say, a borrower's income. Arrears have risen sharply, too, although they are nowhere near as high as in subprime. Around $400 billion of such loans were written last year, which is 13 per cent of the total market and the fastest-growing chunk of it.