The behavior of quote arrivals and bid-ask spreads is examined for continuously recorded deutsche mark-dollar exchange rate data over time, across locations, and by market participants. A pattern in the intraday spread and intensity of market activity over time is uncovered and related to theories of trading patterns. Models for the conditional mean and variance of returns and bid-ask spreads indicate volatility clustering at high frequencies. The proposition that trading intensity has an independent effect on returns volatility is rejected but holds for spread volatility. Conditional returns volatility is increasing in the size of the spread.

ABSTRACT The behavior of quote arrivals and bid‐ask spreads is examined for continuously recorded deutsche mark‐dollar exchange rate data over time, across locations, and by market participants. A pattern in the intraday spread and intensity of market activity over time is uncovered and related to theories of trading patterns. Models for the conditional mean and variance of returns and bid‐ask spreads indicate volatility clustering at high frequencies. The proposition that trading intensity has an independent effect on returns volatility is rejected, but holds for spread volatility. Conditional returns volatility is increasing in the size of the spread.

The authors reply to the comment by D. R. Kamerschen and J. Park on their 1988 paper published in this Review. They find that the econometric point raised by these authors is flawed, because differences in model structure and data are ignored. In particular, the importance of materials input in assessing price-cost margins is reiterated here and illustrated with the 1988 paper's original table. Other points of the comment are refuted by direct reference to statistical results and inferred conclusions in the 1988 paper. Copyright 1993 by MIT Press.