"Why are contracts incomplete? Transaction costs and bounded rationality cannot be a total explanation since states of the world are often describable, foreseeable, and yet are not mentioned in a contract. Asymmetric information theories also have limitations. We offer an explanation based on...

We analyze noncontractible investments in a model with shading. A seller can make an investment that affects a buyer’s value. The parties have outside options that depend on asset ownership. When shading is not possible and there is no contract renegotiation, an optimum can be achieved by...