Lefouili, YassinePinho, Joana2023-10-022023-10-022020-090167-7187http://hdl.handle.net/10400.14/42736We study the price and welfare effects of collusion between two-sided platforms and show that they depend on whether collusion occurs on both sides or a single side of the market, and whether users single-home or multi-home. Our most striking result is that one-sided collusion leads to lower (resp. higher) prices on the collusive (resp. competitive) side if the cross-group externalities exerted on the collusive side are positive and sufficiently strong. One-sided collusion may, therefore, benefit the users on the collusive side and harm the users on the competitive side. Our findings have implications regarding cartel detection and damages actions.engCollusionCross-group externalitiesTwo-sided marketsjournal article10.1016/j.ijindorg.2020.10265685089488930000573442600006