摘要：Common agency models are usually divided into two categories. Public agency assumes that firms (the principals) can contract formally with a common agent, which may be interpreted as a service provider or a client, over the same set of variables, while in private agency at least one principal cannot contract over some variables available to others. This paper studies a setting in which firms are unable to contract formally over some variables but can nevertheless include them in a relational contract, in the sense that some payments cannot be put in force by court and must be self-enforced. I characterize the equilibrium and show that public and private outcomes may be seen as extreme cases when either players are very patient or, respectively, not patient at all. For intermediate discount factors, firms make use of all information available, but the need for self-enforceability limits the incentives that may be credibly offered in equilibrium.
