Margin

Margin - The portion of account equity set aside as collateral to open or maintain positions. MT4 and MT5 use margin requirements defined per symbol (often as a percentage or fixed amount). The Terminal shows Margin used by open trades. If equity drops so that MarginLevel = (Equity/MarginUsed)*100% falls below a threshold, the broker may close positions (margin call). Functions like AccountMargin() return the required margin.