中文摘要：

公司盈利能力显著影响公司的信用评级,进而影响公司债券融资成本的大小,故发债公司存在基于评级的盈余管理动机。选取2007年至2012年发行公司债券且具有信用评级的A股非金融类上市公司为研究样本,采用事件研究法检验发债公司获得首次评级之前盈余管理的分布状况,运用OLS和oprobit回归模型验证盈余管理、公司债券融资成本与首次信用评级之间的关系。研究结果表明,发债公司在获得首次信用评级前,正向的盈余管理程度持续上升,评级后出现持续下调甚至为负的现象;控制公司正常应计利润后,发行公司的盈余管理程度与首次信用评级之间正相关,且主体信用评级表现显著,说明评级机构的决策受发债公司盈余管理行为的影响;另外,债券收益率与信用评级负相关,而考虑盈余管理与评级之间交互项的影响时,市场参与者面对公司的盈余管理行为将要求更高的收益率加以补偿,公司的盈余管理行为减弱了评级对债券收益率的影响。

英文摘要：

The company＇s profitability significantly affect the company＇s credit ratings, and then affect the financing costs of corporate bonds, therefore the companies have earnings management motivation for credit ratings purpose. Selecting the A-share listed and non-financial companies which issued corporate bonds during 2007-2012 as research sample, this paper uses the event study to obtain the distribution of earnings management before initial credit ratings. OLS and ordered probit regression model are employed to verify the relationships among earnings management, financing costs of corporate bonds and initial credit ratings. The results showed that before getting the initial credit ratings, company＇s positive earnings management keeps rising, and becomes a sustained downward tend and even reaches negative values after getting the initial credit ratings. After controlling for the company＇s normal accruals, there has a significant positive correlation between the company＇s initial credit ratings and earnings management, particularly for issuer credit ratings. It means that credit ratings agencies＇ decisions are affected by the company＇s earnings management efforts. In addition, the results also show a strong negative correlation between bond yield and credit ratings. But when considering the impact of the interaction term of earning management and credit ratings on the bond yield, we find significant changes that facing of the company＇s earnings management behavior, market participants require higher yield for compensation. The company＇s earnings management behavior weakens the ratings impact on bond yield.