The margin requirement, i.e. the actual money which you have to deposit in your broker account, is, due to the often-offered high leverage, considerably lower than that of other trading instruments, such as stocks, where you have almost no leverage available or to a much lower degree.
This allows you to make higher profits without the need to deposit huge amounts in your broker account.
In other markets, halts in trading, poor liquidity, or a delay between margin account deficit and the closing of an open position can result in a substantial drop below the margin funds available in the trader’s account.
In such cases, the trader is liable for all losses in equities or futures margin trading; even beyond the amount in the trader’s margin account, and must repay the brokerage for the losses in excess of funds deposited.
In contrast, forex traders are usually not exposed to this risk because positions are usually automatically exited by the broker’s trading platform before the trader’s account goes into deficit.
This means that any loss is usually limited to the size of the margin account, although there are instances where this can happen in Forex, too.
Recent regulatory changes in certain jurisdictions, such as the European Union or Australia, have provided more or total security, at least for retail clients, where now there is a general negative balance protection, although this came at the expense of a severe leverage cut for EU- or Australian-registered brokers.
Elsewhere, it depends on the broker’s terms and conditions.