Fees charged by financial institutions and companies for maintaining accounts. For financial institutions, such as banks and credit unions, the fee may be based on the amount in the account or the number of transactions. For investment companies, such as stock brokerage firms and firms working with mutual funds, the fee is often charged for keeping an account going even though it’s too small for the fund to make a lot of money from it. A fee is also charged by both groups for custodial accounts such as Individual Retirement Accounts.