关于机构对A股股票评级变动后市场相应表现

On the Market Performance Corresponding to the Changes of Agencies' Stock Rating on A-Share

伴随着证券市场的日渐完善,各大券商对股票的评级报告也越来越多。其中评级变动反映了券商对于股票看法的变动,现也成为投资者做出投资决策的依据之一。本文以股票评级变动的机构数量为研究数据,观测评级变动后的相应股票的市场表现,实证分析评级变动机构数量与股票表现之间的关系。研究结果表明,只被一家机构上调评级的股票有较高的收益率,被两家机构上调评级的股票收益不明显,被三家及以上数量机构上调评级的股票收益为负值。

With the ever maturing of securities market,there are an increasing number of rating reports from various stock brokers. Rating changes are reflections of brokers’ changes of view on stock; at the same time, they have now become one of the decisive bases for investors. This article takes the number of agencies which offer stock rating changes as research data to observe the corresponding market performances after rating changes have occurred, and to make an empirical analysis of the relationship between the number of agencies which offer stock rating changes and stock market performance. The study reveals that stocks which only receive ratings improvement from one stock rating agency will have relatively higher rate of return, and stocks which receive ratings improvement from two rating agencies will have intangible rate of return, while stocks which receive ratings improvement from three or more rating agencies will have negative rate of return.