This study analysed how positive, neutral, and negative sustainability news impacted the share prices of American and European energy companies, focusing on short-term market reactions. Our goal was to understand whether or not the sustainability narrative had similar effects on share-holder behaviour in both markets, and whether the COVID-19 pandemic changed the way shareholders invested as they faced uncertainty. We used the event study methodology to analyse the cumulative average abnormal returns (CAAR). We gathered 2134 event studies according to the type of energy source (renewable, fossil fuel or nuclear) and news sentiments. We analysed all global and digital news on sustainability from 2017 to 2020 using the GDELT news database as a source of information, which contains 295,093 viral news stories (high-volume news). The results showed notable differences between the American and European market reactions. The American market was much more optimistic, particularly during the pandemic. At the same time, the European market was more negative, showing declines in prices even in the face of positive news about nuclear and renewable energy. Nevertheless, both markets agreed that nuclear power was still on investors’ agenda. Finally, fossil fuels were less penalised by investors following negative or neutral news than other types of energy and were equally or more rewarded following positive news. So, it could be concluded that fossil fuel investors were less impacted by negative news about the energy market before and during COVID-19. These results could be relevant for policy makers in the context of changing the current shareholders’ narratives and incentives towards an effective sustainable energy transition through the use of new incentives/legislations.