In the past three decades, governments in emerging markets have accumulated large amounts of international reserves, especially those with fixed exchange rates. This article proposes a theory of reserve accumulation that can account for these facts. Using a model of endogenous sovereign default with nominal rigidities, we argue that the interaction between sovereign risk and aggregate demand amplification generates a macroeconomic-stabilization hedging role for international reserves. We show that issuing debt to purchase reserves during good times allows the government to stabilize aggregate demand when sovereign spreads rise and rolling over the debt becomes more expensive. We provide empirical evidence consistent with the model’s predictions.

We measure the effects of debt dilution on sovereign default risk and study debt covenants that could mitigate these effects. We calibrate a baseline model with endogenous debt duration and default risk (in which debt can be diluted) using data from Spain. We find that debt dilution accounts for 78 percent of the default risk in the baseline economy and that eliminating dilution increases the optimal duration of sovereign debt by almost 2 years. Eliminating dilution also increases consumption volatility but still produces welfare gains. The debt covenants we study could help enforcing fiscal rules.