Nash bargaining and renegotiation with social preferences: case of the roundwood log supply contracts

We consider two economic agents, a timber and log supplier and a lumber manufacturer, endowed with the mean-variance utility preferences that negotiate according to the Nash bargaining game. We study both negotiation and renegotiation between a supplier that can be either public-oriented or profit-maximizing and a profit-maximizing manufacturer. We first prove that the Nash bargaining game has a unique equilibrium log supply contract, at which the negotiation takes only place on the prices. We then find that the expected profitmaximizing is achieved when the supplier’s public interest and the manufacturer’s bargaining power are strategic substitutes. The renegotiation reveals the presence of a memory effect over the quantities issued from bargaining. As well, it unveils strategic complementarity of changes in expected profits. The simulations we conduct provide an insight of the model outcomes.