Mortgage Loan Mortgage LoanMortgage debt obligation evidenced, or when made will be evidenced, by the Loan Documents, or  a mortgage debt obligation with a Fannie Mae credit enhancement. purchased by Fannie Mae in exchange for an issued MBS MBSMortgage-Backed Security backed by the Mortgage Loan Mortgage LoanMortgage debt obligation evidenced, or when made will be evidenced, by the Loan Documents, or  a mortgage debt obligation with a Fannie Mae credit enhancement. .