中文摘要：

已有研究表明,股权制衡能够显著影响上市公司价值,但就影响模式与影响程度尚未达到一致。本文使用非参数非线性分位数回归方法,对两者之间关系进行再研究,提出非线性异质效应概念,并建立新的计量模型与方法 ：给出基于B-样条展开的非线性分位数回归模型,能够更加灵活地捕获股权制衡度对上市公司价值的非线性异质影响;给出模型的估计、检验与选择方法,能够实现非线性异质效应的存在性检测;给出条件概率密度预测方法,能够全景刻画股权制衡度对上市公司价值整个条件分布特征的边际贡献,定量测度非线性异质效应的表现形式、影响程度等。通过对我国A股上市公司的实证研究发现,股权制衡对上市公司价值影响存在明显的非线性异质效应：一方面,“倒U型”非线性效应表明,存在最优的股权制衡水平实现公司价值最大化,不能盲目地提升股权制衡水平;另一方面,在不同分位点处的异质效应表明,股权制衡对公司价值具有不同的影响模式,受到公司价值创造能力及所有制属性影响,不能搞“一刀切”的公司治理结构。

英文摘要：

The equity restriction has been proved to have significant influence on enterprise value of listed companies, but the results about the influence pattern and influence degree are far from consensus. To tackle this issue, we re-investigate the relationship between equity restriction and enterprise value through quantile regression approach and propose a new conception and some effective methods for testing nonlinear and heterogeneous effect. First, we use B-spline basis extension to build a nonlinear quantile regression model, which is flexible to describe the influence of equity restric- tion on enterprise value of listed companies. Second, we provide statistical inference methods for model estimation, model test, and model selection. These methods are very useful and effective to test the nonlinear and heterogeneous effect in practice. Third, we present the conditional density forecast through differencing the conditional quantile, which can be used to evaluate the marginal contribution of equity restriction on enterprise value. Our methods can identify the effect and quantitatively measure the outcome and degree of the impact from a complete view, which is not able to be discovered by traditional approach including linear mean regres- sion. In the end, we conduct empirical study on listed companies in Chinese A stock market. The empirical results are very interesting and show that the significant nonlinear and heterogeneous effects are highly significant. On the one hand, the nonlinear effect with inversed U shape indicates that there exists an optimal level of eq- uity restriction to maximize enterprise value, which implies that it is not appropriate to improve the level of equity restriction blindly for practical use. Moreover, the heterogeneous effect indicates that equity restriction has different mode of impact on enterprise value across different quantiles influenced by the ability to create enterprise value and ownership of property, which implies that we should apply a differentiation strategy instead o