Postal Savings Bank's third-party depository business qualification opening time: 201May 3. Third-party depository is a business provided by commercial banks, which is commonly used in securities, futures, real estate and other trading activities. Taking the third-party depository in securities trading as an example, it means that according to the requirements of laws and regulations, the depository bank is entrusted to take charge of the deposit and withdrawal of customers' funds and the delivery of funds, and the securities trading operation remains unchanged.