As such,in our example,Tan will need to meet a margin call for $2,240 when the index falls 6.4 points on 27 August and his margin account dips to $2,760.

• 张三的盘口在8月27日遭受了1280元的损失，造成结算后的保证金余额只剩2760元，低于维持保证金4000元，所以需要补仓。每当补仓时，必须将保证金余额填到初始保证金5000元的水平，所以张三必须再拿出2240元。