Generally, Maintenance Margin is the amount of money an investor must maintain in his or her account to keep an open position (long or short) on a futures contract. Should the value of the investor's account fall below the maintenance margin, his or her brokerage will issue a margin call.
This is different from initial margin, which is the amount of money an investor must have in his or her account to open such a position.
Maintenance Margin is typically lower than initial margin. And, while the two could be equal, necessarily, maintenance margin can never be higher than initial margin.
