This note reconsiders the impact of the reform of the operational framework of the European Central
Bank that took place in March 2004. We estimate a bivariate GARCH model with the overnight rate and
1-year swap rate, where identifying restrictions are imposed on the conditional variance. Differently from
previous studies, we use a measure of structural correlation to show that the 1-year swap segment has
decoupled from the overnight rate as the two rates do not co-vary any longer