Adaptive Expectations and Stock Market Crashes

A theory is developed that explains how stocks can crash without fundamental news and why crashes are more common than frenzies. A crash occurs via the interaction of rational and naive investors. Naive traders believe that prices follow a random walk with serially correlated volatility. Their expectations of future volatility are formed adaptively. When the market crashes, naive traders sell stock in response to the apparent increase in volatility. Since rational traders are risk averse as well, a lower price is needed to clear the market: the crash is a self-fulfilling prophecy. Frenzies cannot occur in this model.

Dynamic Equilibrium Selection: A General Uniqueness Result

This paper shows that in a dynamic context, under weak assumptions, the presence of payoff shocks can shrink the equilibrium set to a singleton. We study a model with a continuum of fully rational agents who switch between two actions or states over time (e.g., working in different sectors, employment vs. unemployment, etc.). An agent's incentive to pick a given action is greater if others do the same. Agents receive chances to change actions at random times and may influence the rate at which these chances arrive. Payoff shocks may follow any of a large class of stochastic processes that includes both seasonal and mean-reverting processes. In this general setting, payoff shocks give rise to a unique equilibrium. One implication is that the introduction of aggregate shocks leads to a unique equilibrium in two well-known macroeconomic search models with multiple equilibria (Diamond and Fudenberg, Howitt and McAfee).

Adaptive Expectations and Stock Market Crashes

A theory is developed that explains how the stock market can crash in the absence of news about fundamentals, and why crashes are more common than frenzies. A crash occurs via the interaction of rational and naive investors. Naive traders believe in a simple (but reasonable) statistical model of stock prices: that prices follow a random walk with serially correlated volatility. They predict future volatility adaptively, as a weighted average of past squared price changes. In a crash, the naive traders lower their demand in response to the apparent increase in volatility. This lowers the risk bearing capacity of the market, so that the lower crash price clears the market. Unlike other explanations of market crashes, this mechanism is fundamentally asymmetric: the stock price cannot rise sharply, so frenzies or bubbles cannot occur.Stock market crashes; adaptive expectations; volatility feedback; excess volatility

Policy Partners: Making the Case for State Investments in Culture

Points to increasing evidence that governors and other state policymakers consider the development of cultural resources integral to comprehensive plans aimed at stimulating regional economic growth

Does Foreign Exchange Intervention Matter? Disentangling the Portfolio and Expectations Effects for the Mark

The time is ripe for a re-examination of the question whether foreign exchange intervention can affect the exchange rate. We attempt to isolate two distinct effects: the portfolio effect, whereby an increase in the supply of marks must reduce the dollar/mark rate (for given expected rates of return) and the additional expectations effect, whereby intervention that is publically known may alter investors expectations of the future exchange rate, which will feed back to the current equilibrium price. We estimate a system consisting of two equations, one describing investors' portfolio behavior and the other their formation of expectations, where the two endogenous variables are the current spot rate and investors' expectation of the future spot rate. We use relatively new data sources: actual daily data on intervention by the Bundesbank, newspaper stories on known intervention, and survey data on investors' expectations. We find evidence of both an expectations effect and a portfolio effect. The statistical significance of the portfolio effect suggests that even sterilized intervention may have had positive effects during the sample period. (It tends to be significant only during the later of our two sample periods, October 1984 to December 1987. That intervention appears less significant statistically during the earlier period, November 1982 to October 1984, could be attributed to the fact that little intervention was undertaken until 1985.) For the magnitude of the effects to be large requires that intervention be publically known. Our (still preliminary) estimates suggest that a typical $100 million of "secret" intervention has an effect of less than 0.1 per cent on the exchange rate, but that the effect of news reports of intervention can be as large as an additional 4 per cent.

STRATEGIC ALLIANCES: CREATING LONG TERM SUCCESS

Given today's increasingly competitive environment, firms in every industry are searching for new ways to increase their competitive advantage. Many firms have realized that, due to a variety of different reasons (e.g., fast-paced technological advances), significant performance improvements cannot be achieved alone. As such, the traditional response of performance enhancement through acquisition is no longer the only option. Strategic alliances are a new alternative that enable partnering firms to combine their individual strengths while compensating for their internal resource scarcities without making the investment required for actual ownership. While interest in alliances is growing, firms are often unsure how to build and maintain successful alliances. This research examines alliances between manufacturers and their suppliers in the food and health/personal care industries to determine what factors lead to successful, long term alliances.Farm Management,