The Home Bias in Sovereign Ratings
研究利用9家评级机构对143个主权国家的数据，发现评级机构对本国及文化、经济、政治相近的国家给予更高评级，文化相似性是主要传导渠道，且这种偏见源于对风险的更乐观认知而非信息优势。
Using data on 143 sovereigns provided by nine agencies based in six countries, we estimate the determinants of sovereign ratings to test whether agencies assign higher ratings to their respective home countries, as well as to economically, geopolitically, and culturally aligned countries. Our regression results show that the respective home country, culturally more similar countries, and countries to which home-country banks have a larger risk exposure receive higher ratings than justified by their economic and political fundamentals. Cultural proximity, as measured by linguistic similarity, is shown to be the main transmission channel that explains the advantage of the home country. Further empirical tests that control for the existence of foreign offices and rated countries’ levels of information transparency suggest that a more optimistic perception of risks rather than informational advantages drives this cultural home bias.