Do Bid-Ask Spreads or Bid and Ask Depths Convey New Information First?

This paper investigates the order in which new information is first reflected in the market – through changes in spreads or through updated depths. We develop an error correction model of spreads and depths and estimate Gonzalo-Granger common factor components using two years of tick-by-tick quote data on all stocks in the Dow Jones Industrial Average. We show that indeed depths rather than spreads are first to impound new information that leads to new quote trends. Specifically, (bid and ask) depths convey information first in virtually every stock in both years, while spreads almost never convey information in 1998, and do so in only 8 out of 30 cases in 1995. Even in those 8 cases, the percentage of new information revealed by spreads ranges from 50-59% with the depths accounting for the rest. Our results have important implications for academic research on asymmetric information trading, for security market design, and for public policy.