We present a tractable dynamic macroeconomic model of self-fulfilling bank runs. A bank is vulnerable to a run when a loss of investors' confidence triggers deposit withdrawals and leads the bank to default on its obligations. We analytically characterize how the vulnerability of an individual...

This paper proposes a theory of foreign reserves as macroprudential policy. We study an open economy model of financial crises, in which pecuniary externalities lead to overborrowing, and show that by accumulating international reserves, the government can achieve the constrained-efficient...

In the past three decades, governments in emerging markets have accumulated large amounts of international reserves, especially those with fixed exchange rates. We propose a theory of reserve accumulation that can account for these facts. Using a model of endogenous sovereign default with...

Sudden Stops are financial crises defined by a large, sudden current-account reversal. They occur in both advanced and emerging economies and result in deep recessions, collapsing asset prices, and real exchange-rate depreciations. They are preceded by economic expansions, current-account...

An equilibrium model of financial crises driven by Irving Fisher's financial amplification mechanism features a pecuniary externality, because private agents do not internalize how the price of assets used for collateral respond to collective borrowing decisions, particularly when binding...

In this paper, we study the optimal design of financial safety nets under limited private credit. We ask when it is optimal to restrict ex ante the set of investors that can receive public liquidity support ex post. When the government can commit, the optimal safety net covers all investors....

We study the optimal accumulation of international reserves in a quantitative model of sovereign default with long-term debt and a risk-free asset. Keeping higher levels of reserves provides a hedge against rollover risk, but this is costly because using reserves to pay down debt allows the...

We develop a quantitative equilibrium model of financial crises to assess the interaction between ex-post interventions in credit markets and the buildup of risk ex ante. During a systemic crisis, bailouts relax balance sheet constraints and mitigate the severity of the recession. Ex ante, the...

We examine banking regulation in a macroeconomic model of bank runs. We construct a general equilibrium model where banks may default because of fundamental or self-fulfilling runs. With only fundamental defaults, we show that the competitive equilibrium is constrained efficient. However, when...