Mortgage LoanMortgage 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. refinancing a Portfolio Mortgage LoanPortfolio Mortgage LoanMortgage Loan purchased by Fannie Mae and held as of a certain date regardless of whether it is a Cash Mortgage Loan or an MBS Mortgage Loan. using streamlined underwriting per Part III, Chapter 18: Choice Refinance Loans.