Money Week: Beware the US Housing Bubble Alan Greenspan, chairman of the US Federal Reserve, has upped the ante. Having said in May that parts of the US housing market were looking frothy, last week he described the US housing boom as an “economic imbalance” and warned that prices, fuelled by “investors accepting lower compensation for risk”, could go into reverse. Basically, says Paul Krugman in The New York Times, he’s saying “beware the bursting bubble”.