我国的双碳目标（2030年前实现碳达峰，2060年前实现碳中和）于2020年9月在联合国大会上正式提出，这标志着我国绿色金融政策即将迎来新一轮高峰， 2021-2023年我国绿色债券市场经历了快速扩容阶段，并产生了碳中和债券等创新品种。在新的时代背景下，绿色债券的信用利差特点依然有待研究，研究绿色金融政策对于降低企业实际融资成本的实际效果具有重要的理论和实践意义。本文探究了绿色溢价的存在性及其特点。实证部分选取2019-2022年间在银行间市场发行的债券数据，采用固定效应模型，以信用利差作为被解释变量，以是否为绿色债券/碳中和债券为解释变量，在控制债券维度、企业性质维度、财务维度等其他变量的情况下，检验绿色溢价的存在性和异质性。实证结果表明：绿色债券存在绿色溢价现象，并且在不同品种、不同评级以及不同所有制发行主体中普遍存在，随着时间推移，绿色溢价在不断提高，同时碳中和债券相比于普通绿色债券，在绿色溢价上的优势也在随时间逐渐凸显，本文通过采取倾向评分匹配（PSM）和直接匹配法筛选配对样本进行稳健性检验。进一步地，本文研究了绿色溢价的影响因素及其作用机制。为检验政策因素对绿色溢价的影响，实证部分采用双重差分模型，选取《银行业评价方案》作为准自然实验，研究发现：将“绿色债券持有量”纳入绿色金融业务评价体系中后，该政策可以通过改变绿色债券的供需直接降低信用利差。此外，不同所有制企业的政策受益程度具有异质性，政策实行后，民企发行的绿色债券信用利差下降幅度更大。为检验信息披露质量对绿色溢价的影响，本文借助内容分析法构建了“绿色项目信息披露程度得分”指标，手工整理得到相关数据，将该指标与“是否有第三方绿色认证”作为衡量信息披露质量的代理指标，研究表明信息披露质量能够通过缓解投资人和发行人间的信息不对称问题从而增强绿色溢价。本文的研究发现对于促进绿色债券市场发展具有一定实践意义。绿色溢价的存在提升了企业发行绿色债券的经济效益和发行意愿。绿色金融政策对于降低企业实际发债成本具有积极效果，加强债券信息披露质量不仅是对投资人的保护，也是发行人能够获得绿色溢价的重要原因之一，因此政府部门不仅可以推进相关利好政策的出台，也应对绿色债券适度监管，提高其信息披露水平。
In September 2020, China put forward the goal of "carbon peaking by 2030 and carbon neutrality by 2060" at the United Nations General Assembly, which marked a new peak of China‘s green financial policies. From 2021 to 2023, the green bond market has experienced a rapid expansion stage, and created new bonds such as carbon neutral bonds. In the new era, the credit spread characteristics of green bonds still need to be studied, and it is of great theoretical and practical significance to study the actual effect of green financial policies on reducing the financing costs of enterprises.This paper studies the existence and characteristics of the green premium. In order to test the existence and heterogeneity of green premium, the empirical part selects the bond data issued in the interbank market from 2019 to 2022, adopts the fixed effect model, takes the credit spread as the explained variable, and takes whether it is a green bond/carbon neutral bond as the explanatory variable. The empirical results show that there is a green premium phenomenon in green bonds, and it generally exists in bonds of different types, different ratings and different ownership issuers. As time goes by, the green premium continues to increase. The advantages of carbon neutral bond are gradually becoming more prominent over time. This paper uses the propensity score matching (PSM) and direct matching methods to screen paired samples for robustness test.Further, this paper studies the influencing factors and influencing mechanism of the green premium. In order to test the impact of policy factors on the green premium, the empirical part adopts the difference-in-differences(DID) model and selects the Banking Evaluation Scheme as a quasi-natural experiment. Results show that the policy can directly reduce credit spreads by changing the supply and demand for green bonds. In addition, the degree of policy benefit of different ownership enterprises is heterogeneous. After the policy was implemented, the credit spread of green bonds issued by private enterprises drops more. In order to test the impact of the information disclosure quality on the green premium, this paper uses the content analysis method to construct the index "green project information disclosure score", uses this index and "whether third-party green certification is available" as two proxy indicators of information disclosure quality. It is empirically found that the information disclosure quality can enhance the green premium by alleviating the information asymmetry between investors and issuers.The findings of this paper have certain practical significance for promoting the development of the green bond market. The existence of the green premium has enhanced the economic benefits and willingness of enterprises to issue green bonds. Green financial policies have a positive effect on reducing the actual cost of issuing bond. Strengthening the bond information disclosure quality is not only to protect investors, but also one of the important causes of the green premium. Therefore, government departments can not only implement relevant favorable policies, but also moderately supervise green bonds and improve their information disclosure quality.
