Trading activity, realized volatility and jumps

This paper takes a new look at the relation between volume and realized volatility. In contrast to prior studies, we decompose realized volatility into two major components: a continuously varying component and a discontinuous jump component. Our results confirm that the number of trades is the dominant factor shaping the volume–volatility relation, whatever the volatility component considered. However, we also show that the decomposition of realized volatility bears on the volume–volatility relation. Trade variables are positively related to the continuous component only. The well-documented positive volume–volatility relation does not hold for jumps.