中文摘要：

设计了一个简单的模型，解释了大额交易冲动，在保证金交易制下，大单交易其实含有一个自动实现的免费期权。这种冲动在2种情况下得到强化：①将操作人员的业绩与奖惩挂钩，因盈利操作得到的奖励比同额的亏损操作得到的惩罚要大；②存在一个公司亏损值，当亏损增加时，对员工的处罚程度已经无可复加，大单交易也给了操作员一个免费期权。这种大单冲动的实现，既可能是公司内控机制的缺陷，还有可能是由于外部监管部门的信息与执行成本过大导致公共监管缺失，因此，应从这2个方面予以完善。

英文摘要：

This essay designs a simple model to explain the impulsion of the large order and concludes the large order implies an automatically executed free option under the margin trading system. This impulsion strengthens under the following two conditions： in one hand, the operators＇ perfor- mance will be associated with the bonus and penalty for the bonus from the profit is larger than the penalty from the loss; in another hand, there is a company loss value, when the loss increases, the degree of the penalty to the operator can not increase, that is the large order gives the operator a free option. However, the execution of the large order impulsion comes from the defect of the company＇s internal control mechanism and the absence of the public supervision which are from the over cost that the external supervision section gets the information and supervises; therefore, solutions are in the two aspects mentioned above.