中文摘要：

过度投资作为低效率的投资方式会破坏企业价值和股东财富，有效的外部治理机制能够约束管理层利用权力实施过度投资寻租的行为。以2006年至2013年中国上市企业数据为样本．以产品市场竞争和外部大股东持股衡量外部治理机制，分别采用单变量分析和多元回归方法，实证研究管理层权力对过度投资的影响以及外部治理机制对过度投资一管理层权力敏感性的影响。研究结果表明，中国上市企业的管理层综合权力越大，过度投资现象越严重。不同管理层权力维度变量对过度投资的影响不同，任职年限长、学历水平高以及持有本企业股份的管理层，越有可能利用手中的权力实施过度投资；总经理与董事长两职兼任有利于降低过度投资行为，提高企业投资效率。产品市场竞争和外部大股东持股均能显著影响过度投资与管理层权力之间关系的敏感性，外部大股东持股比重越高、产品市场竞争越激烈，越能有效抑制管理层利用权力实施过度投资的行为。

英文摘要：

The board of listed firms with dispersed ownership cannot be expected to bargain fairly with managers. As a result, managers with strong power may engage in empire building which will lead to rent seeking by overinvestment. Due to such investment inefficiency, managerial overinvestment can decrease the firm value and its shareholders＇ wealth. Effective external govern- ance mechanism plays a significant role in restricting the managerial rent seeking by overinvestment. In this paper, the product market competition and the ownership of outside blockholders are employed as proxies of external gov- ernance mechanism respectively. As important external governance mechanism, product market competition can affect the man- agement supervision of shareholders, and provide additional information used to mitigate moral hazard and agency costs. In re- turn, it wiU constraint the excessive expansion of managerial power and the managerial rent seeking. Compared with other share- holders, outside blockholders have both motivation and ability to supervise the managerial behavior. The higher the ownership of outside blockholders is, the more supervision of outside blockholders will lead to less managerial rent seeking. This paper investigates the impact of managerial power on overinvestment and the impacts of product market competition and own- ership of outside blockholders on overinvestment-managerial power sensitivity. Our sample includes listed firms on China＇s main board market during the period from 2006 to 2013. We employ Hirshmann-Herfindahl index as measurement of product market competition, and ownership of the second largest shareholder to the fifth largest shareholder as measurement of outside blockhold- ers＇ ownership. And we use univariate analysis and multivariate regression analysis method to do the empirical analysis. The results show that the comprehensive managerial power has significantly positive impacts on the overinvestment of listed Chi- nese firms provided not taking into the account of the impacts