Debauchery and Original Sin: The Currency Composition of Sovereign Debt
研究新兴经济体主权债务的货币构成，解释为何过去以外国货币借款为主（原罪），而近年本地货币借款激增。模型显示，本地债务虽能对冲收入冲击，但会加剧政府偏离稳健货币政策的诱惑，从而限制本地借款；货币政策可信度低的国家则更多借入外币作为替代。
Abstract We present a model that accounts for the “mystery of original sin” and the surge in local-currency borrowing by emerging economies in the recent decade. We quantitatively investigate the currency composition of sovereign debt in the presence of two types of limited enforcement frictions arising from a government's monetary and debt policy: strategic currency debasement and default on sovereign debt. Local-currency debt obligations act as a better consumption hedge against income shocks than foreign-currency debt because their real value can be affected by monetary policy. However, this provides a government with more temptation to deviate from disciplined monetary policy, thus restricting borrowing in local currency more than in foreign currency. Our model predicts that a country with a less credible monetary policy borrows mainly in foreign currency as a substitute for monetary credibility. An important extension demonstrates that in the presence of an expectational Phillips curve, local-currency debt improves the ability of monetary policymakers to commit.