Cecchetti & Schoenholtz — Adverse Selection: A Primer

Information is the basis for our economic and financial decisions. As buyers, we collect information about products before entering into a transaction. As investors, the same goes for information about firms seeking our funds. This is information that sellers and fund-seeking firms typically have. But, when it is too difficult or too costly to collect information, markets function poorly or not at all.

This form of asymmetric information―where two parties to a potential transaction have unequal knowledge―is a particularly serious hindrance to the operation of financial markets. If, for some reason, conditions suddenly make the information asymmetry worse, the consequences can be catastrophic. In a recent post, we described how in August 2007, a sequence of events led financial intermediaries to suddenly question the quality of some securities that many of their counterparties already owned. Not being able to tell safe from unsafe, investors and institutions withdrew from lending. As credit evaporated, many potential transactions stopped taking place all at once.

Economists use the term adverse selection to describe the problem of distinguishing a good feature from a bad feature when one party to a transaction has more information than the other party. The degree of adverse selection depends on how costly it is for the uninformed actor to observe the hidden attributes of a product or counterparty. When key characteristics are sufficiently expensive to discern, adverse selection can make an otherwise healthy market disappear.

The term “adverse selection” comes from the fact that, when the hidden attributes are costly to observe, the quality of the products on offer or of the potential parties to a transaction deteriorates; that is, the pool becomes adverse relative to the full universe of goods (or counterparties) available.

In this primer, we examine three examples of adverse selection: (1) used cars; (2) health insurance; and (3) private finance. We use these examples to highlight mechanisms for addressing the problem....

Money and Banking
Adverse Selection: A Primer
Money and Banking
Stephen G. Cecchetti, Professor of International Economics at the Brandeis International Business School, and Kermit L. Schoenholtz, Professor of Management Practice in the Department of Economics of New York University’s Leonard N. Stern School of Business

Cecchetti & Schoenholtz are the authors of Money, Banking and Financial Markets.