Does Common Analyst Coverage Explain Excess Comovement?

摘要

This article shows that correlated errors in news about fundamentals are an important, rational determinant of excess comovement. Individual analysts' forecast errors tend to be correlated across stocks. Using a proxy for correlated forecast errors based on analyst coverage, I find that stocks with similar sets of analysts exhibit more excess comovement, controlling for industry and other variables. Exogenous changes in commonality in analyst coverage around i) brokerage firm mergers and ii) additions to an index lead to changes in excess comovement. This information channel explains 10% to 25% of the increase in comovement around additions to the S&P 500 index.