Maintenance margin is the amount that must be available in funds in order to keep a margin trade open.
It is also known as the variation margin or “free margin”.
Its purpose is to ensure you have enough money in your account to fund the present value of the position at all times and cover any running losses.
You need enough maintenance margin to “maintain” your open positions.
The maintenance margin is one of the two types of margin required to make a leveraged trade.
The other is the initial margin (or deposit margin), which is the amount needed to open a new position.
To keep a leveraged position open, a certain amount of funds must be paid and kept in your account.
If your position starts to make a loss, then your deposit may no longer be enough to keep the trade open.
In this case, your broker will ask you to increase the funding in your account. This is called a margin call.