Martins, António Miguel ValenteMoutinho, Nuno2024-12-132024-12-132025Martins, António Miguel; Moutinho, Nuno (2025). Stock-term market impact of major cyber-attacks: evidence for the ten most exposed insurance firms to cyber risk. Finance Research Letters. ISSN 1544-6123. 71, p. 1-91544-6123http://hdl.handle.net/10198/30727The main focus of this paper is to study empirically the impact of major cyberattacks in the market value of the ten most exposed insurers to cyber risk. Using an event study for 53 global cyberattacks, we observe a negative and statistically significant stock price reaction for insurers around the cyberattack disclosure dates. The increase in the assessed probability of an increase in future payments tends to prevail over the increase in demand and/or premiums caused by the disclosure of global major cyberattacks. The results of our analysis also show a higher negative stock market reaction for small insurers and when involves financial information loss.engInsuranceCyberattackCyber riskMarket reactionEvent studyjournal article10.1016/j.frl.2024.106361