The amount of money or collateral deposited by a customer with a broker, by a broker with a clearing member, or by a clearing member with the clearinghouse, for the purpose of insuring against loss on open futures contracts. The margin is not partial payment on a purchase. (1) Initial margin is the total amount of margin per contract required by the broker when a futures position is opened; (2) maintenance margin is a sum that must be maintained on deposit at all times. If the equity in a customer’s account drops to, or under, the level because of adverse price movement, the broker must issue a margin call to restore the customer’s equity. Sometimes called a performance bond.