It is time to tackle the systemic flaw in housing policy – reliance on leverage – and introduce minimum downpayment regulations for all homebuyers, writes Charles W. Calomiris

Without high leverage the subprime boom and bust could not have happened. Risky no-docs borrowers would have been unwilling to deceive lenders if they had to pledge a large amount of their own savings as a downpayment (deposit). House price declines would not have produced huge loan losses if homeowners had retained a minimum 20 per cent stake in their homes.

During the 1990s and 2000s leverage tolerances on US government-guaranteed mortgages rose steadily and dramatically at FHA, Fannie Mae and Freddie Mac. The average loan-to-value (LTV) ratio of FHA mortgages rose to 96 per cent, and a third of Fannie and Freddie’s purchases leading up to their insolvencies had LTVs of greater than 95 per cent.

Not only are high LTVs destabilising, they undermine the objectives of housing policy. Its central goal is promoting stronger communities by encouraging residents to have a stake in them. But a 97 per cent LTV creates a trivial stake; homeowners become renters in disguise, able to abandon homes at little cost.