This paper studies a principal-agent relationship when both are risk-neutral and in the presence of adverse selection and moral hazard. Contracts must satisfy the limited-liability and monotonicity conditions. We provide sufficient conditions under which the optimal contract is simple, in the sense that each type is offered the same contract. These are: the action and the agent’s type are complements, and the output’s cumulative distribution function is such that the marginal rate of substitution between the action and the agent’s type is the same for each possible output realization. Furthermore, under the average monotone likelihood ratio property, the optimal contract is a call-option contract as in Innes (J Econ Theory 52(1):45–67, 1990). The results shed light on the fact that sometimes contracts are not highly dependent on individual characteristics as predicted in most pure moral hazard and pure adverse selection settings.

中文翻译：

---

与道德风险、逆向选择和风险中性签约：什么时候一刀切？

本文研究了当两者都是风险中性且存在​​逆向选择和道德风险时的委托代理关系。合约必须满足有限责任和单调性条件。我们提供了使最优合同简单的充分条件，即每种类型都提供相同的合同。它们是：动作和代理的类型是互补的，输出的累积分布函数使得动作和代理类型之间的边际替代率对于每个可能的输出实现是相同的。此外，在平均单调似然比属性下，最佳合约是 Innes 中的看涨期权合约（J Econ Theory 52(1):45-67, 1990）。