TY - CONF T1 - Reassessing the market impact of cyber incidents: A bias-adjusted event study approach A1 - Maréchal, Loïc TI - Modern Finance Conference 2026 Y1 - 2026 CY - Krakow UR - https://mfc3.eventsadmin.com/Papers/ViewContribution?cid=14065&h=55F4E69C4E8EA9FEE4B4B7BD53FF0A1C KW - Cybersecurity KW - Econometrics KW - Event study N2 - This study examines the impact of cyber incidents on shareholder value. Using data from 2012–2022, we measure abnormal stock returns around reported incidents, adjusting for event-induced variance and cross-correlation. Unlike prior research, we find no statistically significant market-wide abnormal returns once these adjustments are applied. However, data breaches stand out as particularly damaging, with average losses of–1.3% (USD–1.9 billion). The health sector is especially vulnerable, with average losses of–5.2%. Our results suggest that cyber risk is priced selectively by markets, with implications for portfolio risk assessment, sector allocation, and investment strategies. ER -