Assessment of the cybersecurity of Ukrainian public companies listed on the Warsaw Stock Exchange S.A.

Nowadays, the number of sophisticated cyberattacks targeting critical infrastructure or banking systems is increas- ing. Cases of successful attacks are not uncommon, as statistics in Ukraine demonstrate, and they are becoming more frequent and advanced. This results in an increased risk for companies listed on the stock exchange. The article provides examples of cyberattacks in Ukraine, including those using ransomware, attempts to infiltrate energy systems, and attacks on government institutions. It is noted that the presence of cyber threats is strongly linked to the politi- cal and international situation of the country. Analyses conducted focus on the examination of cyber threat events in Ukraine and their impact on the WIG_UKRAIN stock index from 2015 to 2023. The evalu- ation includes the index’s return rates on the day of the cyber threat occurrence, the following day, and the average return rate within five sessions after the threat. An analogous study for the WIG index is adopted as a benchmark. Based on the obtained results, it can be said that before the year 2022, cyberattacks on Ukraine did not have a significant impact on the value of the Ukrainian company stock index. The situation changed after 2022, where each potentially economi- cally harmful cyberattack contributed to the decrease in the value of Ukrainian-listed companies. Generally, the start of hostilities in 2022 significantly increased the volatility of the WIG_UKRAIN index quota- tions. This is to be expected, as markets react badly to uncertainty.