The objective of this paper is to compare the effectiveness of financial markets and financial intermediaries in financing new industries and technologies in the presence of diversity of opinion. In markets, investors become informed about the details of the new industry or technology and make their own investment decisions. In intermediaries, the investment decision is delegated to a manager, who is the only one who needs to become informed, which saves on information costs, but investors may anticipate disagreement with the manager and be unwilling to provide funds. Financial markets tend to be superior when there is significant diversity of opinion and information is inexpensive. Journal of Economic Literature Classification Numbers: G1, G2.

In a simple model of borrowing and lending with asymmetric information we show that the optimal, incentive-compatible debt contract is the standard debt contract. The second-best level of investment never exceeds the first-best and is strictly less when there is a positive probability of costly bankruptcy. We also compare the second-best with the results of interest-rate-taking behaviour and consider the effects of risk aversion. Finally we provide conditions under which increasing the borrower's initial net wealth must reduce total investment in the venture.

We study a dynamic general equilibrium model in which firms choose their investment level and capital structure, trading off the tax advantages of debt against the risk of costly default. Bankruptcy costs are endogenous, as bankrupt firms are forced to liquidate their assets, resulting in a fire sale if the market is illiquid. When the corporate income tax rate is positive, firms have a unique optimal capital structure. In equilibrium, firms default with positive probability and their assets are liquidated at fire-sale prices. The equilibrium features underinvestment and is constrained inefficient. In particular there is too little debt and default.

It is generally agreed that speculators can make profits from insider trading or from the release of false information. Both forms of stock-price manipulation have now been made illegal. In this article, we ask whether it is possible to make profits from a different kind of manipulation, in which an uninformed speculator simply buys and sells shares. We show that in a rational expectations framework, where all agents maximize expected utility, it is possible for an uninformed manipulator to make a profit, provided investors attach a positive probability to the manipulator being an informed trader.

How should new securities be designed? Traditional theories have little to say on this: the literature on capital structure and general equilibrium theories with incomplete markets takes the securities firms issue as exogenous. This article explicitly incorporates the transaction costs of issuing securities and develops a model in which the instruments that are traded are chosen optimally and the economy's market structure is endogenous. Among other things, it is shown that the firm's income stream should be split so that in every state all payoffs are allocated to the security held by the group that values it most.

A complex financial system comprises both financial markets and financial intermediaries. We distinguish financial intermediaries according to whether they issue complete contingent contracts or incomplete contracts. Intermediaries such as banks that issue incomplete con-tracts, e.g., demand deposits, are subject to runs, but this does not imply a market failure. A sophisticated financial system–a system with complete markets for aggregate risk and limited market participation–is incentive-efficient, if the intermediaries issue complete con-tingent contracts, or else constrained-efficient, if they issue incomplete contracts. We argue that there may be a role for regulating liquidity provision in an economy in which markets for aggregate risks are incomplete. 1 Markets, intermediaries and crises For a long time, it has been taken as axiomatic that financial crises are best avoided. We confront this conventional wisdom by showing that, under certain conditions, a laisser-faire financial system achieves the incentive-efficient or constrained-efficient allocation.1 Further-more, constrained efficiency may require financial crises in equilibrium. The assumptions

The authors describe a model of general equilibrium with incomplete markets in which firms can innovate by issuing arbitrary, costly securities. When short sales are prohibited, firms behave competitively and equilibrium is efficient. When short sales are allowed, these classical properties may fail. If unlimited short sales are allowed, imperfect competition may persist even when the number of potential innovators is large. If limited short sales are allowed, perfect competition may obtain in the limit, but equilibrium can be inefficient because of the presence of an externality: the private benefits of innovation for firms differ from the social benefits.

Empirical evidence suggests that banking panics are related to the business cycle and are not simply the result of “sunspots.” Panics occur when depositors perceive that the returns on bank assets are going to be unusually low. We develop a simple model of this. In this setting, bank runs can be first‐best efficient: they allow efficient risk sharing between early and late withdrawing depositors and they allow banks to hold efficient portfolios. However, if costly runs or markets for risky assets are introduced, central bank intervention of the right kind can lead to a Pareto improvement in welfare.

Financial contagion is modeled as an equilibrium phenomenon. Because liquidity preference shocks are imperfectly correlated across regions, banks hold inter-regional claims on other banks to provide insurance against liquidity preference shocks. When there is no aggregate uncertainty, the first-best allocation of risk sharing can be achieved. However, this arrangement is financially fragile. A small liquidity preference shock in one region can spread by contagion throughout the economy. The possibility of contagion depends strongly on the completeness of the structure of interregional claims. Complete claims structures are shown to be more robust than incomplete structures.

In an overlapping generations economy with (incomplete) financial markets but no intermediaries, there is underinvestment in safe assets. In an economy with intermediaries and no financial markets, accumulating reserves of save assets allows returns to be smoothed, nondiversifiable risk to be eliminated, and an ex ante Pareto improvement compared to the allocation in the market equilibrium to be achieved. In a mixed financial system, however, competition from financial markets constrains intermediaries so that they perform no better than markets alone.