Question

which is the custodian of all banks​

Answer 1

A custodian is a financial institution that holds customers' securities for safekeeping so as to minimize the risk of their theft or loss. A custodian holds securities and other assets in electronic or physical form. Since they are responsible for the safety of assets and securities that may be worth hundreds of millions or even billions of dollars, custodians generally tend to be large and reputable firms. A custodian is sometimes referred to as a "custodian bank."