分析师评级变动会加剧投资者的羊群行为吗？
Do Analyst Rating Changes Exacerbate Investors’ Herding Behavior?

投资者羊群行为是引起股市风险增加的重要因素之一，对其影响因素的研究可以帮助防范化解重大金融风险。本文使用2014~2022年A股日度数据，使用面板数据回归方法实证检验了分析师评级变动对投资者羊群行为的影响，结果发现：1) 分析师评级变动会显著地增大散户和中户投资者羊群行为，对大户和机构投资者羊群行为无显著影响。2) 在声誉的作用下，明星分析师上调评级会对散户和中户投资者羊群行为产生更大影响。3) 分析师一天内发布的评级变动次数越多，越能引起投资者的羊群行为；熊市阶段分析师的评级变动对机构投资者羊群行为也有了显著影响。4) 分析师下调评级会增加散户和中户投资者的买入羊群行为，这显示了散户和中户投资者的非理性投资行为，并且散户投资者非理性行为更严重。
Investor herding behavior is one of the significant factors contributing to increased risks in the stock market, and research on its influencing factors can help prevent and mitigate major financial risks. This article uses daily data for the A-share market from 2014 to 2022 and implements a panel data regression method to empirically examine the impact of analyst rating changes on investor herding behavior. The results show that: 1) Analyst rating changes significantly increase the herding behavior of individual and intermediary investors, with no significant impact on the herding behavior of large investors and institutional investors. 2) Under the influence of reputation, star analysts’ upward rating revisions have a greater impact on the herding behavior of individual and intermediary investors. 3) The more rating changes an analyst releases within a day, the more likely it is to trigger investor herding behavior; during bear market phases, analysts’ rating changes also have a significant impact on the herding behavior of institutional investors. 4) Analyst downgrades increase the herding behavior of buying among individual and intermediary investors, which demonstrates the irrational investment behavior of individual and intermediary investors, and the irrational behavior of individual investors is more severe.