Natural gas is an important source of energy in the global economy, hence understanding the drivers of its prices is of significant interest for the many economic agents. This paper investigates the role of inventories for the dynamics of the U.S. natural gas market. Our contribution is twofold. First, within the threshold structural VAR framework we demonstrate that in a low inventory regime spot prices are more responsive to economic fundamentals in comparison to situation in which the inventories are high. Second, we present evidence that the level of natural gas inventories have a significant effect on the relationship between spot and futures prices. (C) 2020 Elsevier B.V. All rights reserved.