Vertical relations, opportunism, and welfare
研究上游垄断企业与多个零售商签订秘密线性合同时的机会主义问题，比较秘密合同与公开合同下的市场扭曲程度，发现零售商策略互补时秘密合同扭曲更严重，并探讨对反垄断信息交换的启示。
Abstract This article revisits the opportunism problem faced by an upstream monopolist contracting with several retailers over secret agreements, when contracts are linear. We characterize the equilibrium under secret contracts and compare it to that under public contracts in a setting allowing for general forms of demand and retail competition. Market distortions are more severe under secret contracts if and only if retailers' instruments are strategic complements. We also investigate the effect of opportunism on firms' profits. Our results remain robust whether retailers hold passive or wary beliefs. We derive some implications for the antitrust analysis of information exchange between firms.