We address the growing concern that minority shareholding (MS) in rival firms may lessen competition, using the introduction of national leniency programs (LPs) as a shock that destabilizes collusive agreements. Based on data from 63 countries, we find a large and significant immediate increase in domestic horizontal MS acquisitions once an LP is introduced but only in countries where the LP is deemed to be effective. There is no effect on non-horizontal or cross-border MS acquisitions. Our findings suggest that firms may use MS acquisitions to either stabilize collusive agreements or soften competition in the event that collusion breaks down.