The Informational Role of Prices
Over the past decade, Sanford Grossman's contributions to the economics ofinformation have significantly altered the way economists think about rational expectations. Herehis articles are collected in one place, providing a uniform framework for understanding how pricesconvey information in securities markets.Grossman elaborates a new model of economic equilibriumthat casts a dual role for prices both as constraints that affect the immediate costs or benefits ofacts and as conveyers of information about the probable future costs and benefits of those acts. Hepoints to the Wall Street panic of October 1987 as an example of the informational role of priceswhere volatility actually represented sophisticated trading strategies by relatively uninformedindividuals.In the first two chapters, Grossman interprets the ideas presented in the articles inlight of recent developments in financial markets, looks at selected contributions to the new andstill expanding literature on the informational role of prices, and introduces the rationalexpectations model of demand price equilibrium.Six chapters then take up the informational role ofprices in competitive stock markets, and future markets (where Grossman's "noisy rationalexpectations" model provides rewards for discovering new information). They look at theimpossibility of informationally efficient markets, the implications of program trading and dynamichedging strategies for stock and futures price volatility, and takeover bids. The last two chaptersconcentrate on the informational role of contracts -- warranties and private disclosure aboutproduct quality, and the implication of unemployment with observable aggregate shocks. Economistscollaborating with Grossman on several chapters include J. E. Stiglitz, Oliver Hart, and EricMaskin.Sanford Grossman is Professor of Finance at The Wharton School, University of Pennsylvania.The Informational Role of Prices is included in the Wicksell Lectures series.