A Custodian Bank is a financial institution that holds customers' securities for safekeeping to prevent them from being stolen or lost. The custodian may hold stocks or other assets in electronic or physical form on behalf of their customers. Customers may have access to their assets through the custodian, which may offer investment services as well.A custodian bank is important because it allows investors to buy and sell securities without having to worry about losing them. The bank also offers a secure place for customers to store their money and other investments, which can help protect them from theft or fraud. Custodians are typically very reliable and trustworthy institutions, which is why many people choose to use their services when investing in the stock market.