With house prices in some parts of the US down 40 per cent in the past two years – and with many parts of the country still experiencing falls – stabilising the housing market has become a top priority for the US government.

The losses on houses have not just hit homeowners – the banks and investors that lent people money for mortgages have taken huge hits. The losses have swept around the world, reflecting the fact that billions of dollars of securities that were sold were backed by US mortgage payments.