MBS InvestorMBS InvestorFor MBS Mortgage Loans, either a Third Party MBS Investor for Lender-Arranged Sales, or the Multifamily Trading Desk. for an MBS Mortgage LoanMBS Mortgage LoanMortgage Loan purchased by Fannie Mae in exchange for an issued MBS backed by the Mortgage Loan. , or Fannie Mae for a Cash Mortgage LoanCash Mortgage LoanMortgage Loan purchased by Fannie Mae in exchange for cash. .