The purpose of this paper is to investigate contract renegotiation in multi-agent situations where risk averse agents negotiate a contract offer to the principal after they observed a common, unverifiable perfect signal about their actions. Renegotiation gives the agents gains from mutual insurance.

The purpose of the paper is to investigate how side track (or collusion) among agents affects the principal's welfare in a hidden action model. We assume that the agent's actions are mutually observable but not contradictable among them and hence direct coordination of actions via side...