For more than two decades, research on incentives and market equilibrium in sit-
uations with asymmetric information has been a proliÞc part of economic theory. In
1996, the Bank of Sweden Prize in Economic Sciences in Memory of Alfred Nobel
was awarded to James Mirrlees and William Vickrey for their fundamental contri-
butions to the theory of incentives under asymmetric information, in particular its
applications to the design of optimal income taxation and resource allocation through
different types of auctions. The theory of markets with asymmetric information rests
Þrmly on the work of three researchers: George Akerlof (University of California,
Berkeley), Michael Spence (Stanford University) and Joseph Stiglitz (Columbia Uni-
versity). Their pioneering contributions have given economists tools for analyzing a
broad spectrum of issues. Applications extend from traditional agricultural markets
to modern Þnancial markets.1
Why are interest rates often so high on local lending markets in Third World
countries? Why do people looking for a good used car typically turn to a dealer rather
than a private seller? Why do Þrms pay dividends even if they are taxed more heavily
than capital gains? Why is it in the interest of insurance companies to offer a menu of
policies with different mixes of premiums, coverage and deductibles? Why do wealthy
landowners not bear the entire harvest risk in contracts with poor tenants? These
questions exemplify familiar but seemingly different phenomena, each of which
posed a challenge to traditional economic theory. This years laureates showed that
these and many other phenomena can be understood by augmenting the theory
with the same realistic assumption: one side of the market has better information than
the other. The borrower knows more than the lender about his creditworthiness; the
seller knows more than the buyer about the quality of his car; the CEO and board of
a Þrm know more than the shareholders about the proÞtability of the Þrm; insurance
clients know more than the insurance company about their accident risk; and tenants
know more than the landowner about harvesting conditions and their own work effort.
1See Riley (2001) for a survey of developments in the economics of information over the last 25
years.
1