A method and system for creating and transacting a mortgage product that is backed by a mortgaged property and additional financial instruments. The mortgage product requires the determination of the value of a property to be purchased to be associated with an index for real estate in a region where the property is located, purchasing at least one put option contract on the index, and combining the contract with a loan to form the mortgage product. If there is a decrease in the index, the contract can be exercised so as to protect both mortgagor and mortgagee.