We operate a stop out system, which means that if the equity on your account falls below 30% of the required margin for the open position, the system will automatically start closing out positions, beginning with the position making the greatest loss.
The cost of trading is cumulative, so you must have enough funds to support all of your open positions, or you may be stopped out. However, the forex market is highly volatile, and if you have a very low margin level at the time of economic news releases or under other abnormal conditions, the market can rapidly move against you, and the system will close open positions at the next best available price, which could cause you to lose the whole deposit or even more.
Also, if you are holding positions over a weekend when we are closed, the market can open out of line from the close on Friday, causing extended losses.