Common stock portfolios of large, heavily traded firms exhibit daily first-order serial correlation in excess of what would be expected, given the individual security coefficients. Further, this correlation rises as the number of securities in the portfolio increases. The direct implication of this finding is that nonsynchronous trading is not the only cause of correlation in daily market indices. Related implications are also discussed.

The question of whether security return distributions have a finite or an infinite variance has been debated for many years. The possibility that the security return-generating process actually has an infinite variance is particularly vexing since it implies that all statistical techniques and theoretical frameworks utilizing the second (or higher) moment are invalid. While this is clearly not a disaster—alternatives do exist—much of the work which has been done in the field of finance has assumed the existence of the second moment. It is, therefore, important to determine whether or not the security return distribution actually has a finite variance.

ABSTRACT Using a test statistic which specifically allows for parameter shifts over time, we investigate the time‐variance relationship of security returns. The null hypothesis of stationary and independent increments is rejected, and the existence of a complex short‐term reversal phenomenon is reported.

Using a test statistic which specifically allows for parameter shifts over time, we investigate the time-variance relationship of security returns. The null hypothesis of stationary and independent increments is rejected, and the existence of a complex short-term reversal phenomenon is reported.

The focus of this paper i s on the escape clause petitions filed under the Trade Act of 1974 (Section 201). First, the capital marketevent study method is used to analyze the effects of protection decisions. Then, cross-section regressions are performed to examine the influence of key variables on the observed market reaction. The authors conc lude that while protection is beneficial to beleaguered industries, the extent o f such benefits is quite narrowly circumscribed and is conditional on internal v ariables for each firm. Protection is thus not the panacea that its advocates cl aim. Copyright 1986 by MIT Press.