Maintenance Margin
Financial trading platforms require clients to keep maintenance margins. This is the cash that must be in the account to cover trading losses. If the maintenance margin is insufficient, clients will receive margin calls, which are demands to deposit more cash in the account to cover loss-making positions. The margin is the cost of putting on the trade. It is a small amount of the overall exposure of the position. The remainder is borrowed from the broker, hence trading in this way can be highly leveraged.