A savings account that offers the competitive rate of interest (real rate) in exchange for larger-than-normal deposits. Also known by the acronym "MMDA", which stands for "money market demand account" or "money market deposit account". |||Many money market accounts place restrictions on the amount of transactions you can make in a month (such as five or less). Furthermore, you usually have to maintain a certain balance in the account to receive the higher rate of interest. Some banks require at least $500, others require a much higher balance.