Allaudeen Hameed is a Professor of Finance at National University of Singapore. This post is based on an article authored by Professor Hameed; Randall Morck, Professor of Finance at the University of Alberta; Jianfeng Shen, Senior Lecturer in Finance at the University of New South Wales; and Bernard Yeung, Professor of Finance at National University of Singapore.
Stocks followed by more analysts should be priced more accurately, yet their returns are unusually prone to co-move with market and industry indexes. Stocks that co-move more are often thought to be related to herding. This is because more informed trading ought to make a firm’s stock price move with the changing fortunes of that specific firm, as well as with market and industry trends. More firm-specific price variation in less-followed stocks seems counterintuitive, yet this is what we observe.
In our paper, Information, Analysts, and Stock Return Comovement, forthcoming in The Review of Financial Studies, we resolve this seeming paradox. Stocks covered by more analysts co-move more precisely because they are priced more accurately and their price movements help investors update the prices of less-followed stocks. This “information spillover” makes most price movement in highly-followed stocks look like comovement with industry or market trends, but in fact investors are using information about highly-followed stocks to deduce how other stocks ought to move.