We test whether airline consolidations generate monopoly profits by examining returns to listed carriers around horizontal airline-acquisition bids and evaluating effects of industry concentration on share-price reactions. Under Civil Aeronautics Board (CAB) regulation, returns to targets, bidders, and rival carriers are positive functions of changes in concentration implied by bids. Changes in concentration after deregulation have no positive effect on carrier returns. These results support Jordan's (1970, 1972) hypothesis that CAB activities fostered carrier collusion. There is no evidence of monopoly gains from carrier consolidations after deregulation.

This paper asks whether market fundamentals can explain the recent run-up and decline of Japanese equity values and price-earnings ratios. Accounting differences explain about half of the long-run disparity between U.S. and Japanese P/Es. For example, if Japanese firms used U.S. accounting rules, the Japanese P/E ratio would have been 32.6, not 53.7, in 1989. Accounting differences cannot, however, explain the doubling of this ratio in 1986, nor its decline in 1990. Similarly, we are unable to isolate changes in required stock returns or growth expectations that are large enough to explain recent Japanese stock price movements.

Habit persistence in preferences and durability of consumption goods both imply time-nonseparability in the derived utility for consumption expenditures. We study a simple model with both effects. Lagged consumption expenditures enter the Euler equation, where habit persistence implies that their coefficients are negative and durability implies positive coefficients. Estimating the sign of the coefficients addresses the question of which effect is dominant. Earlier empirical work on monthly data supports the durability of consumption expenditures. We find evidence in monthly, quarterly, and annual data that habit persistence dominates the effect of durability.

In this paper, we present a simple model which relates security returns to three components: an expected return, a bid-ask error, and white noise. The relative importance of the various components is empirically assessed, and the model's ability to explain the various time-series properties of individual security and portfolio returns is tested. Time-varying expected returns and bid-ask errors are found to explain substantial proportions (up to 24%) of the variance of security returns. We also reconcile the typically negative autocorrelation in security returns with the strong positive autocorrelation in portfolio returns.