This paper studies how the presence of an antitrust authority affects market-sharing agreements made by firms in oligopolistic markets. These agreements prevent firms from entering each other´s market. The set of market-sharing agreements defines a collusive network, which is under suspicion by...

One simple way to endogenize the degree of cross ownership in an industry is that rms give away part of their pro ts. We show that this possibility of unilaterally giving pro ts away to the rival previous to Bertrand competition opens the door to multiple equilibria. In the symmetric duopoly...