AbstractWe consider a multimarket framework where a set of firms compete on two oligopolistic markets. The cost of production of each firm allows for spillovers across markets, ensuring that output decisions for both markets have to be made jointly. Prior to competing in these markets, firms can establish business intelligence gathering links with other firms. A link formed by a firm generates two types of externalities for competitors and consumers. We characterize the business intelligence equilibrium networks and networks that maximize social welfare. By contrast with single‐market competition, we show that in multimarket competition there exist situations where intelligence‐gathering activities are underdeveloped with regard to social welfare and should be tolerated, if not encouraged, by public authorities.