Security Return Distributions and Market Structure: Evidence from the NYSE/AMEX and the NASDAQ Markets

This paper documents significant and persistent deviations from normality in security return distributions for the NYSE, AMEX, and NASDAQ from 1974 to 1988. Controlling for January and size effects, we find that the deviations of security return distributions from normality decline with increasing portfolio size and investment horizon for the NYSE and AMEX, especially for daily returns. Deviations appear to be greater for the NASDAQ than for the two exchanges even for firms of the same size. Ratios of monthly to daily variances are also larger for the NASDAQ. These results suggest that nonparametric or other robust statistical techniques should be used when valuing equity options and other derivatives, especially when examining NASDAQ security returns. They further imply that trading strategies based on market inefficiencies are more likely to succeed on the NASDAQ.