We consider an environment in which risk-neutral firms must obtain external finance. They have access to two kinds of linear, stochastic investment opportunities. For one, return realizations are costlessly observed by all agents. For the other, return realizations are costlessly observed only by the investing firm; however, they can be (privately) observed by outsiders who bear a fixed verification cost. Thus, the second investment opportunity is subject to a standard costly state verification (CSV) problem of the type considered by Townsend (1979), Gale and Hellwig (1985), or Williamson (1986, 1987).

We examine the optimal allocations of investment between the two kinds of projects, as well as the optimal contract used to finance it. We show that the optimal contractual outcome can be supported by having firms issue appropriate (and determinate) quantities of debt and equity securities to outside investors.

The optimal debt-equity ratio necessarily depends (in part) on the firm’s asset structure. Investments in projects subject to CSV problems are associated (in a sense to be made precise) with the use of debt—as might be expected from the existing CSV literature. Investments in projects with publicly observable returns are associated with the use of external equity.

We examine in detail the relationship between the optimal asset and liability structure of the firm. We also describe conditions under which an increase in the cost of state verification shifts the composition of investment towards projects with observable returns, and reduces the optimal debt-equity ratio. Interestingly, the optimal debt-equity ratio is also shown to depend on factors that are irrelevant to asset allocations.

Finally, a large part of the interest in CSV environments has been due to the fact that they may result in equilibrium credit rationing. Our analysis has strong implications for the possibility of equilibrium credit rationing in more general CSV models.

We produce a theoretical framework that helps explain the co-evolution of the real and financial sectors of an economy in the growth process, as described by Gurley and Shaw. According to them, self-financed capital investment first gives way to debt finance and later to the emergence of equity as an additional instrument for raising funds externally. As the economy develops further, the aggregate ratio of debt to equity will generally fall. We analyze that portion of their account concerning the evolution of equity markets. We show that in an important sense, debt equity are complementary sources for the financing of capital investments.

Three economic environments are reviewed, and in each organizations play an essential role. For an adverse selection insurance economy, we find that when mutual insurance arrangements are permitted an equilibrium necessarily exists and is optimal. This example, and the two others, illustrate the problems that may result from imposing organizational structure on an environment rather than permitting the structure to be determined endogenously.

Many claims have been made about the potential benefits and the potential costs of adopting a system of universal banking in the United States. We evaluate these claims using a model where there is a moral hazard problem between banks and "borrowers," a moral hazard problem between banks and a deposit insurer, and a costly state verification problem. Under conditions we describe, allowing banks to take equity positions in firms strengthens their ability to extract surplus, and exacerbates problems of moral hazard. The incentives of universal banks to take equity positions will often be strongest when these problems are most severe.