This paper offers the first systematic quantitative assessment of default-option interventions designed to mitigate Google’s search dominance. By analyzing interventions in the European Economic Area, Russia, and Turkey, we find that, across all three cases, changes to default settings effectively reduced Google’s market share. The causal impact amounts to less than 1 percentage point in the EEA and over 10 percentage points in Russia and Turkey. Differences arise from intervention nuances, including the size of the targeted users’ group, local market characteristics, and remedy designs.