Ambrogio Cesa-Bianchi, Ed Hall, Marco Pinchetti and Julian Reynolds

The remarkable stability of US inflation dynamics in the pre-Covid era had led many to think that the Phillips Curve had flattened. However, the sharp rise in inflation that followed the Covid-19 pandemic ignited a debate on whether the Phillips Curve had steepened and, in particular, whether its slope depends on some particular macroeconomic conditions. Which are these conditions, though? In this post, we argue that one important candidate that could explain this kind of state-dependency in the slope of the Phillips Curve is global supply chain constraints. We propose a simple framework to account for this state-dependency, and conduct econometric analysis on US data which supports its implications – showing that inflation in the US is more responsive to slack when supply constraints are tighter.