The US has already faced its black swan event. A roughly 15 per cent slump in house prices across the country since the boom ended is something that many senior risk managers and, clearly, rating agencies thought could never happen. It helped turn credit markets upside down during a dramatic repricing of risk, before they regained some semblance of normality. But what if the swan turns out to be an even rarer shade, say pink – and home prices continue to slump even beyond the levels that bruised investors have priced in?

The head of a US bank outlined to me, calmly, the doomsday scenario. It goes something like this: the overhang of US houses on the market is already at an elevated 11 months’ worth of sales. To bring it down to a more normal level of about five months, transaction rates would have to rise significantly, or houses worth almost $600bn would need to disappear from the market. The problem is that buyers are unlikely to rush in if they think that their dream house will get even cheaper. Also, most people require mortgage financing. And banks, bruised by the credit dislocation and facing balance sheet constraints, are still wary about lending to all but the safest borrowers whose mortgages can be guaranteed by the likes of Fannie Mae and Freddie Mac. So there is the risk of a downward spiral. Inventories could remain stubbornly high, or even rise as buyers stay on the sidelines and lenders remain cautious. That could be exacerbated if rising oil prices sap consumer spending power further and inflation concerns push long-term Treasury yields, and hence mortgage rates, higher.