我们假设张三的经纪商对他要求的初始及维持保证金各是5000元及4000元(也就是交易所规定的最低保证金数额；

• He must have %245,000 in his margin account for his long position, assuming that the initial margin and the maintenance margin his broker requires of him are %245,000 and %244,000, respectively. (Tan's broker cannot lower the margins below the minimum levels set by Simex.