Is after-hours trading informative?

This article investigates price and trading volume relations for near term crude oil contracts at the New York Mercantile Exchange (NYMEX). The study investigates the informativeness of after-hours trading under the prior assumption that daytime and after-hours trading sessions are completely segmented. The research methodology uses a vector autoregressive (VAR) structural model to identify the lead/lag structure between the leading overnight session and the lagging daytime session. This framework permits us to impose testable restrictions in considering the view that after-hours price changes and trading volumes provide contemporaneous information in the daytime price discovery process. Furthermore, the reduced-form VAR allows testing whether innovations (surprises) in daytime prices and trading activity influence overnight price/volume behavior.