This paper considers an extension of the univariate autoregressive conditional duration model to which durations from a second stock are added. The model is empirically used to study durations in two traded stocks, Ericsson B and AstraZeneca, on the Stockholm Stock Exchange. It is found that including durations from a second stock may add explanatory power to the univariate model. Ericsson B is Granger causing durations in AstraZeneca, while AstraZeneca is not Granger causing durations in Ericsson B. Volume, spread and trade intensity changes have significant effects for both series.