The fundamental determinants of interest rate differentials in the ERM

The paper analyses the sources of persistent interest rate differentials <italic>vis-à-vis</italic> Germany that have existed in Belgium, Denmark, France, Ireland, Italy, and the Netherlands. In a target zone system like the ERM, interest rate differentials mainly reflect devaluation expectations, which are measured here by raw 1-month Euromarket interest rate differentials, drift-adjusted 1-month differentials, and differentials in long-term government bond yields. The role of a large set of fundamental macroeconomic variables that may have affected these devaluation expectations is investigated within a vector autoregressive (VAR) setting, by means of Granger-causality tests, impulse-response functions and variance decompositions. We find no evidence that fundamentals are more relevant to drift-adjusted devaluation risk than for unadjusted interest rate differentials. A significant impact of inflation, budget deficits, and unemployment becomes evident for almost all ERM-participants.