How should potential anticompetitive effects of a proposed merger be assessed in a “two-sided” market, when the target only participates in one side of the market? In decisions issued one day apart, the US District Court for the District of Delaware and the UK Competition & Markets Authority (“CMA”) reached opposing conclusions on this issue. In the US, the District Court allowed the merger to proceed after concluding that the US Department of Justice (“DOJ”) failed to prove that Sabre Corporation’s proposed acquisition of Farelogix Inc. was likely to substantially lessen competition in a two-sided market. The District Court found that Sabre, which operates a two-sided airline ticket platform serving airlines and travel agents, does not compete with Farelogix, since Farelogix only provides services to airlines. The CMA, by contrast, examined the impact of the merger on ticket merchandizing and distribution services that Sabre and Farelogix each supply to airlines on one side of the market and found that the merger was likely to substantially lessen competition for those services. As a result, the CMA blocked the transaction. Following the issuance of the conflicting decisions, Sabre and Farelogix terminated their proposed transaction.