A trust company, bank or similar financial institution responsible for holding and safeguarding the securities owned within a mutual fund. A mutual fund's custodian may also act as the mutual fund's transfer agent, maintaining records of shareholder transactions and balances.

Also referred to as a "mutual fund corporation".

Watch: Mutual Funds

Since a mutual fund is essentially a large pool of funds from many different investors, it requires a third-party custodian to hold and safeguard the securities that are mutually owned by all the fund's investors. This structure mitigates the risk of dishonest activity by separating the fund managers from the physical securities and investor records.