In this paper I develop a model of a competitive financial system with unrestricted but costly entry and an endogenously determined number of competing financial institutions (“banks” for short). Banks can make standard loans on which plentiful historical data are available and unanimous agreement exists on default probabilities. Or banks can innovate and make new loans on which limited historical data are available, leading to possible disagreement over default probabilities. In equilibrium, banks make zero profits on standard loans and positive profits on innovative loans, which engenders innovation incentives for banks. But innovation brings with it the risk that investors could disagree with the bank that the loan is worthy of continued funding and hence could withdraw funding at an interim stage, precipitating a financial crisis. The degree of innovation in the financial system is determined by this trade-off. Welfare implications of financial innovation and mechanisms to reduce the probability of crises are discussed.

This paper proposes a new framework for understanding financial intermediation. In contrast to previous research, we consider a setting in which intermediaries possess no inherent information processing or monitoring advantages. Instead, in an economy with overly optimistic entrepreneurs who require funding from pessimistic investors, we show that intermediaries can arise endogenously. In such a setting, only a rational intermediary will be sufficiently optimistic to find it worthwhile to invest in a technology for screening entrepreneurs' projects, and yet be pessimistic enough to use this technology. Our framework produces implications consistent with heretofore unexplained stylized facts, and conjectures which are thus far untested.

We develop a theory of banking that explains why banks started out as commodities warehouses. We show that warehouses become banks because their superior storage technology allows them to enforce the repayment of loans most effectively. Further, interbank markets emerge endogenously to support this enforcement mechanism. Even though warehouses store deposits of real goods, they make loans by writing new fake warehouse receipts, rather than by taking deposits out of storage. Our theory helps to explain how modern banks create funding liquidity and why they combine warehousing (custody and deposit-taking), lending, and private money creation within the same institutions. It also casts light on a number of contemporary regulatory policies.

An enduring puzzle is why credit rating agencies (CRAs) use a few categories to describe credit qualities lying in a continuum, even when ratings coarseness reduces welfare. We model a cheap-talk game in which a CRA assigns positive weights to the divergent goals of issuing firms and investors. The CRA wishes to inflate ratings but prefers an unbiased rating to one whose inflation exceeds a threshold. Ratings coarseness arises in equilibrium to preclude excessive rating inflation. We show that competition among CRAs can increase ratings coarseness. We also examine the welfare implications of regulatory initiatives.

RMBS sponsors contributed to the rise of new product features in securitized mortgages prior to the 2008 financial crisis. Using a regulatory shock to sponsor competition , we show securitization influences the design of mortgage contracts, empirically demonstrating a unique, feedback loop of product differentiation from the derived security (MBS) to the underlying asset (loans). Product differentiation in Prime MBS collateral rises faster than that of non-prime in the early boom period (2000–2004), a strategic choice by MBS sponsors in the face of increasing competition. At very high levels of competition, product differentiation targets non-prime (marginal) borrowers. We develop a theoretical framework for sponsor-induced product differentiation that explains these empirical findings.