Política Monetária e a Fragmentação do Mercado de Obrigações na Zona Euro: Uma Análise Comparativa entre a Crise Financeira Global e a Crise Pandémica

Abstract

A common monetary policy cannot be transmitted evenly when financing conditions diverge across euro-area countries. This dissertation compares the global financial and sov-ereign debt crises with the pandemic crisis to assess whether the European Central Bank (ECB) contained fragmentation more effectively in the second episode and what this meant for Portugal. Using an observational, retrospective and comparative design, it combines the literature with ECB documents and Eurostat data on monthly long-term sovereign yields, spreads over Germany, real GDP growth, public debt and asset purchase programmes, in-cluding the Pandemic Emergency Purchase Programme (PEPP). Market tension is measured through an average fragmentation index for Portugal, Italy, Spain and Greece, cross-country dispersion and windows around selected interventions. In 2009-2013, the index averaged 5.02 percentage points and dispersion 3.20; in 2020-2021, the corresponding values were 1.14 and 0.34. It exceeded 2 percentage points in 45 of 60 months in the first window, but in none of the 24 months in the second. Fragmentation was thus less intense and persistent during the pandemic, despite the fall in output and rise in public debt. The analysis is de-scriptive and does not isolate each measure's causal contribution. Nevertheless, the findings are consistent with more effective preservation of monetary transmission and market access by the ECB, while concerns about moral hazard, market dependence and fiscal dominance remain. Timely and proportionate anti-fragmentation tools should therefore be accompanied by policies that reduce national vulnerabilities and strengthen the European framework.