and on the single-family mortgage loans held in our portfolio and (ii) trust management income, which is a fee we earn derived from interest earned on cash flows between the date of remittance of mortgage and other payments to us by servicers and the date of distribution of these payments to MBS certificateholders.

 

The aggregate amount of single-family guaranty fees we receive in any period depends on the amount of Fannie Mae MBS outstanding during that period and the applicable guaranty fee rates. The amount of Fannie Mae MBS outstanding at any time is primarily determined by the rate at which we issue new Fannie Mae MBS and by the repayment rate for the loans underlying our outstanding Fannie Mae MBS. Less significant factors affecting the amount of Fannie Mae MBS outstanding are the extent to which Fannie Mae purchases loans from its MBS trusts because of borrower default (with the amount of these purchases affected by rates of borrower defaults on the loans) or because the loans do not conform to the representations made by the lenders.

 

Mortgage Securitizations

 

Our most common type of securitization transaction is referred to as a “lender swap transaction.” Mortgage lenders that operate in the primary mortgage market generally deliver pools of mortgage loans to us in exchange for Fannie Mae MBS backed by these loans. After receiving the loans in a lender swap transaction, we place them in a trust that is established for the sole purpose of holding the loans separate and apart from our assets. We serve as trustee for the trust. Upon creation of the trust, we deliver to the lender (or its designee) Fannie Mae MBS that are backed by the pool of mortgage loans in the trust and that represent a beneficial ownership interest in each of the loans. We guarantee to each MBS trust that we will supplement amounts received by the MBS trust as required to permit timely payment of principal and interest on the related Fannie Mae MBS. We retain a portion of the interest payment as the fee for providing our guaranty. Then, on behalf of the trust, we make monthly distributions to the Fannie Mae MBS certificateholders from the principal and interest payments and other collections on the underlying mortgage loans.

 

The following diagram illustrates the basic process by which we create a typical Fannie Mae MBS in the case where a lender chooses to sell the Fannie Mae MBS to a third-party investor.