Background and aims: The lockdown of sports and gambling venues during the coronavirus disease 2019 (COVID-19) pandemic caused a fear of increased gambling on other online gambling types, with a risk for transfer to more addictive gambling than otherwise. This study aimed to estimate changes in gambling activity during COVID-19-affected periods among all gamblers at a Swedish state-owned gambling operator and to analyse observable sex differences. Methods: This study included gambling tracking data from the Swedish state-owned gambling operator Svenska Spel Sports & Casino (sports betting, online bingo, casino and poker). All individuals (n 5 616,245) who gambled at least once from February 10 to July 19, 2020, were included. The study period was divided into four periods according to their expected level of COVID-19 impact on gambling opportunities: one pre-COVID period and three COVID-affected periods (sports cancellation, emerging return of sports, substantial return of sports). Results: Sports betting experienced an apparent decrease, followed by a gradual normalization and an end level substantially below prepandemic levels. For online bingo, gambling levels increased upon sports interruption and then decreased with the return to normality in sports events but remained higher than baseline levels. We observed a similar trend for online poker during the interruption of sports, but with a lower level than baseline levels when sports events normalized. We noticed a trend favouring online casinos during the sports interruption period regarding gambling intensity but not wagering levels. Discussion and conclusions: Dramatic changes in the content of the gambling market may divert some gamblers to other gambling types, but maintained effects could not be demonstrated.  Kulcsszavak: COVID-19, gambling disorder, gambling tracking data, online gambling