Does Beta Move with News? Firm-Specific Information Flows and Learning about Profitability
研究发现股票贝塔系数在公司发布盈利公告时会上升，并在两到五天后回落，且上升幅度与公告意外程度、对其他公司的信息含量及事前不确定性正相关，支持投资者利用公告信息修正对整体经济盈利预期的学习模型。
We investigate whether stock betas vary with the release of firm-specific news. Using daily firm-level betas estimated from intraday prices, we find that betas increase on earnings announcement days and revert to their average levels two to five days later. The increase in betas is greater for earnings announcements that have larger positive or negative surprises, convey more information about other firms in the market, and resolve greater ex ante uncertainty. Our results are consistent with a learning model in which investors use information on announcing firms to revise their expectations about the profitability of the aggregate economy. The Author 2012. Published by Oxford University Press on behalf of The Society for Financial Studies. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com., Oxford University Press.