The Impact of Extreme Cyberattacks on Market Valuations

Matt Ryan, Glenn Withers, and Frank den Hartog published their paper, “The Impact of Extreme Cyberattacks on Market Valuations: An In-Depth Economic Analysis”, in the Australian Journal of Management in October 2025.  By examining more than two decades of extreme cyber incidents, the research shows how these risks translate into sustained market underperformance fopr corporate shares, often persisting well into the second year after an attack. The results challenge the assumption of rapid market recovery and highlight the growing financial weight of modern threats, particularly ransomware. It is our hope that this work advances ongoing efforts to quantify cyber risk in economically meaningful terms and supports better decision-making for firms, investors, and policymakers.

Professor Withers is the Director of the Social Cyber Institute and co-author of the concept of "Creating Social Cyber Value" published in 2019, along with Professor Greg Austin. Dr Matt Ryan is an advanced researcher at the University of New South Wales Canberra. He is a leading practitioner of cyber security management. Frank den Hartog is a Professor at the University of Canberra where he holds the Cisco Research Chair in Critical Infrastructure. He is an Adjunct Fellow at UNSW Canberra, specialising in complex wireless networked systems research and analysis.