We analyze a model of imperfect price competition between intermediation service providers. We insist on features that are relevant for informational intermediation via the Internet: the presence of indirect network externalities, the possibility of using the nonexclusive services of several...

In standard auctions, collusion among buyers eliminates bidding competition despite informational asymmetries. Collusion can, however, be imperfect when the situation involves "externalities" among buyers, that is, when a buyer is worse off if one rival wins the good rather than if nobody gets...

In many markets, including payment cards and telecommunications, service providers operate networks that support customer transactions with each other. When the two sides of a transaction belong to more than one network in common, the question arises as to which network will carry the...