Without the balance sheet of commercial banks, mortgage bonds issued are no longer liabilities of commercial banks, but liabilities of "specific trading institutions". So it is also called off-balance sheet mortgage securitization.

The key link of mortgage securitization is "real sale", that is, the securitization sponsor sells the portfolio loan to a specialized agency (SPV), thus isolating the loan return risk from the loan sponsor's own risk. The identification of "true sale" involves the presentation of securitization in financial statements. If the loan transfer is financing, the funds obtained by the transferor will be treated as liabilities and the loan will remain on the balance sheet. If the transfer is regarded as a sale, the book value of the loan will be crossed off the balance sheet.

Housing mortgage loan is a kind of loan provided by the bank to ensure the safety of the loan. The borrower's real estate, securities and other documents can legally obtain the lien and pledge of the borrower's property through certain contracts.