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Credit Rationing in Markets with Imperfect Information

Why this mattered

Stiglitz and Weiss’s paper mattered because it overturned the simple competitive-market intuition that excess demand for loans should be eliminated by raising the interest rate. In their model, the interest rate is not just a price: it also changes the composition and behavior of borrowers. Higher rates can attract riskier applicants through adverse selection and induce borrowers to choose riskier projects through moral hazard. As a result, a bank’s expected return may fall when it raises rates, making it rational to deny credit to some borrowers even when they are willing to pay more. Credit rationing was therefore shown not as a temporary friction or regulatory artifact, but as an equilibrium outcome of markets with imperfect information.

The paradigm shift was broader than banking. The paper helped establish that informational imperfections can fundamentally change the logic of markets, so prices need not clear markets and decentralized outcomes need not be efficient. After Stiglitz and Weiss, economists could model credit constraints, underinvestment, and unequal access to capital as endogenous consequences of private information rather than as anomalies outside standard theory. This became foundational for later work in financial economics, development economics, macroeconomics, and contract theory, especially research on collateral, screening, relationship lending, financial accelerator mechanisms, and the role of credit-market failures in business cycles and poverty traps.

Its influence also lay in connecting microeconomic information problems to large-scale economic outcomes. If credit markets ration funds even in equilibrium, then investment, firm growth, entrepreneurship, and household opportunity can depend on wealth, collateral, and institutional design rather than only on project quality or willingness to pay. That insight helped make imperfect-information models central to modern economics and contributed to the intellectual trajectory recognized in Stiglitz’s later Nobel-winning work on markets with asymmetric information.

Abstract

Stiglitz and Weiss explain credit rationing in markets with imperfect information.

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