大股东在公司治理中作用的实证分析

在公司治理中，大股东拥有控制权优势，从而为其侵害中小股东利益提供了便利条件。同时，大股东也有可能通过加强监督等行为为提高公司价值做出贡献。利用中国证券市场研究数据库（CSMAR）中国上市公司中的34个有效样本，以控制权交易价格和小额股权交易价格的差额估算控制权私有收益，以总资产现金收益率（RCF）作为上市公司经营业绩的衡量指标，研究结果表明，大股东在获得控制权后，对公司所做的贡献为正，贡献度为13．01％，但侵害度也达到6．9I％。由此可见大股东治理具有双重效应：努力监督减少经理层的代理成本有利于公司业绩的改善，但利用控制权为自己谋取私利也损害了公司价值。因此，对大股东的监督努力进行合理的补偿以强化其积极作用，并且防止大股东侵占中小股东利益以弱化其消极作用，是完善公司治理机制的重要方向。

Effects of large shareholders in corporate governance

The large shareholders have the facilities to expropriate the interests of small shareholders because of their advantages of control in corporate governance. At the same time, the large shareholders may also contribute to enhance the value of the company through the strengthening of supervision. Using 34 effective listed company samples in China Securities Market Research Database （CSMAR）, estmating the private benefits of control by the difference between the transaction price of control equities and that of small equities, measuring the performance of a listed company by the assets＇ Return of Cash Flow （RCF）, the research shows that the contribution is 13.01% and the expropriation is 6.91% after the big shareholders get the control of a company.The paper proved that the big shareholders possess dual effects in the corporate governance： the positive effect in reducing the agency cost by monitoring managers and the negative effect in seeking for personal gains. Therefore, this paper considers it is the key to compensate reasonably the large shareholders＇ monitoring efforts in order to strengthen their positive effect, and it is key how to prevent their expropriation in order to weaken their negative effect in improving the corporate governance.