Knowledge that Transforms

The authors of this article present convincing evidence that opening prices differ from closing prices. Their major empirical finding is that returns that are measured from the opening of the market to the next open have higher variance than returns measured from the close of trade to the next close. This result is also found in Amihud and Mendelson (1987), but this article improves on the Amihud-Mendelson study by using a larger sample and by conducting a number of other tests. What is special about opening prices? The authors argue that the higher volatility of open-to-open returns is due to the strategic behavior of the specialist. The specialist sets the opening price in the call auction market that occurs at the open and is allowed to trade from his own account at this price. The authors suggest that in exploiting his monopoly position, the specialist increases the effective bid-ask...

This article examines the linkages between equity markets. The authors present a detailed analysis of the correlations between roughly coincident returns in different equity markets. They also uncover an intriguing fact: The volatility of the London stock market is higher than usual around the time when the NYSE opens. This may support their contagion theory, which argues that traders in one market draw inferences about shocks to share-price fundamentals from observed price movements in other markets. Even price moves which are not generated by fundamentals can therefore affect many markets. The findings raise two basic questions about the comovements in international equity markets. The first is whether there is any reason to expect the correlations across markets to be stable through time. This article emphasizes that returns on the London, New York, and Tokyo markets were more highly correlated around the market break of October 1987 than in other periods....

In this article, we characterize economies in which both cash flows and forward prices follow random walks. We show in the case of geometric random walks that the preferences of the representative investor are of the constant proportional risk-aversion type. We also show the conditions under which spot prices follow random walks and under which the equivalent martingale measure is non-state-dependent.

This article analyzes the behavior of stock return volatility using daily data from 1885 through 1988. The October 1987 stock market crash was unusual in many ways. October 19 was the largest percentage change in market value in over 29,000 days. Stock volatility jumped dramatically during and after the crash. Nevertheless, it returned to lower, more normal levels more quickly than past experience predicted. I use data on implied volatilities from call option prices and estimates of volatility from futures contracts on stock indexes to confirm this result.

Event studies often include cross-sectional regressions of announcement effects on exogenous variables. If the event is voluntary and investors are rational, then standard OLS and GLS estimators are inconsistent. Consistent ML estimators are constructed for a cross-sectional model of horizontal mergers relating announcement effects to exogenous characteristics of firms and industries. The OLS and ML estimates differ dramatically for bidders but not for targets. The evidence suggests that managers of bidders, but not targets, have valuable private information about the potential synergies from proposed mergers.

Results of tests contrasting tax-loss selling with intertemporal information variation as explanations of the January seasonal in stock returns are reported. Closed-end fund shares display the typical size-related January seasonal while their net asset values do not. Interpreting the net asset value return as a proxy for information about underlying assets, this result indicates information variation is not a necessary condition for the January effect in stocks. The share returns at the turn of the year are negatively related to their mean preceding year returns and positively related to the standard deviations of their preceding year returns. These results are consistent with tax-loss selling.

We investigate product-market competition when managers maximize shareholder value rather than their expected discounted value of profits. If shareholders are imperfectly informed about future profitability, shareholder-value maximization can lead to either more or less aggressive product-market strategies. Lower rivals’ profits lead investors to believe that the firm’s costs are low relative to those of its rivals and that the industry’s prospects are poor. If the former (latter) inference dominates, each firm tries to lower (raise) its rivals’ profits to increase its own stock price. We also consider implications for corporate financial structure.

The stock market crash of October 1987 led to a boom in conferences, commissions, and studies of the stock market. In almost each case, the participants would try to understand the events of October 1987 by a detailed analysis or description of events during the particular days of high volatility. Of course, to us economists there was nothing qualitatively unusual about October 19, 1987; the stock market moved, and we have no model that succeeds in explaining the magnitude or sources of daily stock market volatility for that day or any other day. When asked by the National Bureau of Economic Research to organize yet another conference on this subject, I decided that it was time to put these events in a historical perspective and try to understand them in the context of longer time periods and broader models. The papers collected in this symposium issue admirably succeed in broadening...

This study investigates experimental financial markets in which firms possess more information than do potential investors. Firms were given opportunities to undertake positive net present value projects which they could either forgo or finance by selling equity. Auctions were conducted among the investors for the right to finance the projects. When the theoretical equilibrium was unique, theory predicted well. When theory permitted pooling, separation, and semiseparation, only the more efficient pooling equilibrium was observed. The domination of the pooling equilibrium was robust to different experimental experiences by participants. When available, signals were used by good firms to distinguish themselves from bad.