Background and aims: COVID-19 resulted in the shutdown of almost all sporting competitions and most venue-based gambling opportunities. This study examines how wagering operators in Australia responded, by examining their advertising. Methods: The study compared Twitter activity during lockdown (March-May 2020) to the previous year for four major wagering operators. Results: Wagering operators continued to advertise in earnest, changing their marketing mix to include more race betting content, as races continued to operate. Most also promoted the only sports available, such as table tennis or esports. When sports resumed, sports betting advertising quickly returned to normal, or exceeded previous levels. Despite more content being available in the case of two operators, engagement from the public during lockdown was similar to or lower than previously. Discussion and conclusion: These results indicate that gambling operators can adjust quickly to major changes. These shifts appear to have been successful, with the increase in race betting during this period almost completely offsetting the decreases in sports betting. This is likely due in part to changes in advertising, which have been associated with increased betting activity, particularly amongst vulnerable people. Responsible gambling messages were virtually non-existent on Twitter, which contrasts with mandatory requirements in other media. The study highlights that regulatory changes to advertising, e.g., banning some content, are likely to be met with substitution of content, rather than reduction, unless advertising volume is also capped. The study also highlights the adaptive capacity of the gambling industry in the face of major disruption to supply.  Kulcsszavak: gambling, advertising, COVID-19, Twitter