Risk Management for Sustainable Sovereign Debt Financing

Abstract

The sharp increase of sovereign debt internationally, since the 2008 global financial crisis, decisively contributed to several sovereign debt crises. The current COVID-19 pandemic and the fact that public debt remains high globally, have prompted a renewed interest in debt sustainability analysis (DSA) and in policy discussions concerning the most appropriate variables. We develop a normative DSA model to manage tail risk and optimize debt-financing decisions with sustainability conditions on debt stock and flow, under macroeconomic, financial, and fiscal uncertainty. We show that a risk management view alters a government’s debt-financing policy to manage tail risk better. Many uncertain variables confound the problem, and portfolio optimization using stochastic programming on scenario trees provides a versatile and effective tool to achieve sustainable debt dynamics. The model is an essential building block of the European Stability Mechanism framework to assess debt sustainability of eurozone member states, including the repayment capacity of crisis countries under €295bn assistance programs.