This paper adds to research on the effect of cyber events on the attacked firm’s value in light of conflicting results from previous studies. Using 536 cyberattack announcements that occurred during the 2007–2016 period, the main goal is to investigate for changes in investor reaction over time as cyberattacks have become more frequent. Empirical evidence shows that cumulative abnormal returns of attacked firms were volatile earlier in the period, became increasingly negative, but have moderated recently. This paper proposes and discusses potential explanations for this observed U-shaped pattern over the 10-year period. The relation between stock market reaction and type of attack, type of data affected, type of perpetrator and various firm level characteristics is also examined.

鉴于以前的研究结果相互矛盾，本文进一步研究了网络事件对受攻击企业价值的影响。使用2007年至2016年期间发生的536次网络攻击公告，主要目标是调查随着网络攻击变得越来越频繁，投资者反应随时间的变化。经验证据表明，受攻击企业的累积异常收益在此期间初期波动较大，逐渐变为负值，但最近有所减弱。本文提出并讨论了这种在十年内观察到的U形模式的潜在解释。还检查了股市反应和攻击类型，受影响的数据类型，犯罪者类型以及各种公司级别特征之间的关系。