Comparitech analyzed 28 breaches suffered by 24 companies with shares listed on the New York Stock Exchange. On average companies that suffered a breach under-performed the NASDAQ by -3.7% after one year. The most significant impact from a breach was felt 14 days after the event, Comparitech found. After a month, share prices tended to catch up with the NASdaq after a month. Finance and payment companies were hit hardest and breaches featuring credit card and Social Security number had the greatest impact.”]
Source: https://www.darkreading.com/attacks-breaches/report-data-breaches-hit-share-prices-too