Résumé : This study evaluates the macroeconomic effects of Outright Monetary Transaction (OMT)announcements by the European Central Bank (ECB). Using high-frequency data, we find that OMTannouncements decreased the Italian and Spanish 2-year government bond yields by about 2percentage points, while leaving unchanged the bond yields of the same maturity in Germany andFrance. These results are used to calibrate a scenario in a multi-country model describing the macrofinanciallinkages in France, Germany, Italy, and Spain. The scenario analysis suggests that thereduction in bond yields due to OMT announcements is associated with a significant increase in realactivity, credit, and prices in Italy and Spain with relatively muted spillovers in France and Germany.