In a traditional fixed rate mortgage, the borrower pays a fixed amount each period regardless of the value of the mortgaged property. One problem with this contract is that the borrower is less willing to pay when the house value falls. This was clearly seen in the 2008 financial crisis and its aftermath when mortgage default rates and foreclosures skyrocketed as the housing market crashed. A more efficient contract design should link payments to house prices so that the borrower's incentive to pay is not undermined by a decline in property value. In addition this design can save the lender the deadweight foreclosure costs. In this paper we examine two proposed index linked mortgages which have this risk sharing feature. We analyze the effect of both designs on borrower incentives in a multi-period setting.

In a traditional fixed rate mortgage, the borrower pays a fixed amount each period regardless of the value of the mortgaged property. One problem with this contract is that the borrower is less willing to pay when the house value falls. This was clearly seen in the 2008 financial crisis and its aftermath when mortgage default rates and foreclosures skyrocketed as the housing market crashed. A more efficient contract design should link payments to house prices so that the borrower's incentive to pay is not undermined by a decline in property value. In addition this design can save the lender the deadweight foreclosure costs. In this paper we examine two proposed index linked mortgages which have this risk sharing feature. We analyze the effect of both designs on borrower incentives in a multi-period setting.