An Analysis of Cyber Breaches and Effects on Shareholder Wealth

Abstract Cyber data breaches are an evolving risk facing all firms and threatens their ability to conduct business activity. Due to a lack of available information, very little is known about the frequency and severity of data breaches and the financial markets’ responses to them. This study uses a unique proprietary data set that includes cyber data breach information for 3,992 publicly traded firms during the 1990 to 2019 period. We find cyber breaches vary with time and cyber criminals focus on particular industries, types of information, access sources, and countries. We find significant short run negative abnormal returns around the announcement of cyber events and larger negative returns in industries with higher frequencies of attacks and attacks involving personal financial information. Additionally, we find increasing negative cumulative abnormal returns up to 250 days after the announcement.