Knowledge that Transforms

The authors examine the effects of renegotiation in an agency relationship. They show how renegotiation affects (1) the set of actions the principal can induce the agent to take and (2) the cost of implementing a given action. The authors show that, when the principal receives an unverifiable signal of the agent's action, renegotiation can improve welfare. This result stands in contrast to earlier findings that renegotiation lowers welfare when the principal receives no signal about the agent's action prior to renegotiation. Copyright 1991 by The Econometric Society.

This paper demonstrates that an optimizing model of a monetary economy can produce perfect foresight equilibria in which the price level fluctuates forever. Cyclically or chaotically fluctuating equilibria are more likely to exist when the rate of money supply growth is high. Furthermore, the set of equilibrium prices may have a complicated topological structure, which poses a more serious problem concerning the validity of comparative statics method than any sort of indeterminacy previously discussed in the literature. Copyright 1991 by The Econometric Society.

Econometrics

A test for long-run memory that is robust to short-range dependence is developed. It is a simple extension of Mandelbrot's "range over standard deviation" or R/S statistic, for which the relevant asymptotic sampling theory is derived via functional central limit theory. This test is applied to daily, weekly, monthly, and annual stock returns indexes over several different time periods. Contrary to previous findings, there is no evidence of long-range dependence in any of the indexes over any sample period or sub-period once short-term autocorrelations are taken into account. Illustrative Monte Carlo experiments indicate that the modified R/S test has power against at least two specific models of long-run memory, suggesting that stochastic models of short-range dependence may adequately capture the time series behavior of stock returns.

ABSTRACT The underpricing of initial public offerings (IPOs) that has been widely documented appears to be a short‐run phenomenon. Issuing firms during 1975–84 substantially underperformed a sample of matching firms from the closing price on the first day of public trading to their three‐year anniversaries. There is substantial variation in the underperformance year‐to‐year and across industries, with companies that went public in high‐volume years faring the worst. The patterns are consistent with an IPO market in which (1) investors are periodically overoptimistic about the earnings potential of young growth companies, and (2) firms take advantage of these “windows of opportunity.”

SEQUELSARE RARELY AS good as the originals, so I approach this review of the market efficiency literature with trepidation. The task is thornier than it was 20 years ago, when work on efficiency was rather new. The literature is now so large that a full review is impossible, and is not attempted here. Instead, I discuss the work that I find most interesting, and I offer my views on what we have learned from the research on market efficiency.