Crisis Poison Pills*
研究发现，市场动荡期间许多公司采用毒丸计划；新冠疫情期间，股价下跌后采用毒丸的公司股价上涨，尤其是有积极股东持股或高危机暴露行业的企业，表明危机毒丸可能通过阻止破坏性所有权变更来保护现有股东。
Abstract We show that a large number of firms adopt poison pills during periods of market turmoil. Specifically, during the coronavirus pandemic, many firms adopted poison pills following declines in valuations, and stock prices increased upon the announcement of firms’ poison pill adoption. Stock price increases are driven by (1) firms in which activist shareholders acquire ownership stakes and (2) firms in industries that had high exposure to the crisis. Likewise, we find a positive reaction to pills with provisions directed at stalling activists’ interventions. Our results suggest that crisis pills that target potentially disruptive ownership changes may benefit current shareholders. Received August 14, 2020; editorial decision October 23, 2020 by Editor Andrew Ellul. Authors have furnished an Internet Appendix,which is available on the Oxford University Press Web site next to the link to the final published paper online.