中文摘要：

本文借鉴集体决策理论和代理理论，考察中国上市公司控股股东性质和股权集中度与经营风险之间的关系。我们发现，（1）非国有产权控股的上市公司的经营风险明显地高于国有产权控股的上市公司，这与非国有产权控股的上市公司经理人员的决策权力更大、经理人员的堑壕效应程度更小、以及这些公司面临的经营环境不确定性程度更高有关。（2）股权集中度和经营风险之间存在着非线性的U型关系，即股权更加集中或者更加分散都有可能导致更高的经营风险，而相对集中的股权制衡结构所导致的经营风险较小，进一步地，这种现象仅在国有控股的上市公司中存在。（3）此外，公司规模和多元化程度与经营风险之间存在着显著的负相关关系，而负债率则与经营风险之间存在着显著的正相关关系。

英文摘要：

Using group decision-making theory and agency theory, we examine the relationship between ownership structure （type of controlling shareholder and ownership concentration） and operating risk in China＇s listed companies. First we find that operating risk in state-controlled firms is significantly lower than in non-state-controlled firms. The latter have higher risk because managers have more decision-making power and are less apt to become entrenched, and these firms face a more uncertain operating environment. Second, a non-linear, U-shaped relation exists between ownership concentration and operating risk, where firms with a highly concentrated or highly diversified ownership structure have greater operating risk, whereas a moderately concentrated structure with checks and balances from outside blockholders leads to lower operating risk. Third, we find that the non-linear, U-shaped relation between ownership concentration and operating risk exists only in state-controlled firms. Finally, size and diversification are significantly and negatively related to operating risk, while leverage is significantly and positively related to the same.