When you use margin products, you are opening positions, which are bigger, then your real deposit. Your losses and profits will be calculated on the total value of your positions and not on your margin requirements. In fact, you are using a sort of credit to invest and the margin is a form of guarantee you need to block into the account, in order to keep the position opened. The review of the margins is, therefore, performed to mitigate at our best the risk for the clients and the bank on certain positions, in case of market adverse situations, increased volatility, and a single or extraordinary event.