We analyze a long-term contracting problem involving common uncertainty about a parameter capturing the productivity of the relationship, and featuring a hidden action for the agent. We develop an approach that works for any utility function when the parameter and noise are normally distributed...

In a model with multiple Pareto-ranked equilibria we add trade in assets that pay based on the realization of a sunspot. Asset trading restricts the equilibrium set in a way that raises welfare by eliminating equilibria with a high likelihood of disasters. When the probability of a disaster is...

Investment of U.S. firms responds asymmetrically to Tobin's Q: investment of established firms -- 'intensive' investment -- reacts negatively to Q whereas investment of new firms -- 'extensive' investment -- responds positively and elastically to Q. This asymmetry, we argue, reflects a...

Growth of technological variety offers more scope for the division of labor. And when a division of labor requires some specific training, the technological specificity of human capital grows and, with it, probably the firm specificity of that capital. We build a simple model that captures this...

Electricity and Information Technology (IT) are perhaps the two most important general purpose technologies (GPTs) to date. We analyze how the U.S. economy reacted to them. The Electricity and IT eras are similar, but also differ in several important ways. Electrification was more broadly...

We reexamine several bodies of data on the growth of output, labor, and capital, within the context of a model that admits the possibility of an externality to the capital input. The model is an augmented version of Paul Romer's (1987) reformulation of the Solow model. Unlike Romer, however, we...

A satisfactory account of the postwar growth experience of the United States should be able to come to terms with the following three facts: 1. Since the early 1970's there has been a slump in the advance of productivity. 2. The price of new equipment has fallen steadily over the postwar period....

This paper studies optimal investment policies when the production function depends on capital of various vintages. In such an environment it is natural to ask whether the firm will invest in old-vintage capital at all. In this paper I derive such a condition. Predictably, investment in old...

Stock-market crashes tend to follow run-ups in prices. These episodes look like bubbles that gradually inflate and then suddenly burst. We show that such bubbles can form in a Zeira-Rob type of model in which demand size is uncertain. Two conditions are sufficient for this to happen: A declining...

A paradigm is presented where both the extent of financial intermediation and the rate of economic growth are endogenously determined. Financial intermediation promotes growth because it allows a higher rate of return to be earned on capital, and growth in turn provides the means to implement...