Academic Publications

•  A Model of the Gold Standard (with Jesús Fernández-Villaverde)   Lecture Notes

              Journal of Economic Theory   volume 214 (2023), pp. 1-23

Abstract: We present a micro-founded monetary model of a small open economy to examine the behavior of money, prices, and output under the gold standard. In particular, we formally analyze Hume's celebrated price-specie flow mechanism. Our framework incorporates the influence of international trade on the money supply in the Home country through gold flows. In the short run, a positive correlation exists between the quantity of money and the price level. Additionally, we demonstrate that money is non-neutral during the transition to the steady state, which has implications for welfare. While the gold standard exposes the Home country to short-term fluctuations in money, prices, and output caused by external shocks, it ensures long-term price stability as the quantity of money and prices only temporarily deviate from their steady-state levels. We discuss the importance of policy coordination for achieving efficiency under the gold standard and consider the role of fiat money in this environment. We also develop a version of the model with two large economies. 

•  Should Central Banks Issue Digital Currency? (with Todd Keister) Technical Appendix (containing all proofs)

             Review of Economic Studies  volume 90 (2023), pp. 404-431

Abstract: We study how introducing a central bank digital currency affects equilibrium allocations and welfare in an environment where both currency and bank deposits are used in exchange. We highlight an important policy tradeoff: while a digital currency tends to improve efficiency in exchange, it may also crowd out bank deposits, raise banks' funding costs, and decrease investment. We derive conditions under which targeted digital currencies, which compete only with physical currency or only with bank deposits, raise welfare. If such targeted currencies are infeasible, we illustrate the policy tradeoffs that arise when issuing a single, universal digital currency.

• Central Bank Digital Currency: Central Banking for All? (with Jesús Fernández-Villaverde, Linda Schilling, and Harald Uhlig)

           Review of Economic Dynamics  volume 41 (2021), pp. 225-242

Abstract: The introduction of a central bank digital currency (CBDC) allows the central bank to engage in large-scale intermediation by competing with private financial intermediaries for deposits. Yet, since a central bank is not an investment expert, it cannot invest in long-term projects itself, but relies on investment banks to do so. We derive an equivalence result that shows that absent a banking panic, the set of allocations achieved with private financial intermediation will also be achieved with a CBDC. During a panic, however, we show that the rigidity of the central bank's contract with the investment banks has the capacity to deter runs. Thus, the central bank is more stable than the commercial banking sector. Consumers internalize this feature ex-ante, and the central bank arises as a deposit monopolist, attracting all deposits away from the commercial banking sector. This monopoly might endanger maturity transformation. 

• Can Currency Competition Work? (with Jesús Fernández-Villaverde)

            Journal of Monetary Economics  volume 106 (2019), pp. 1-15

Abstract: Can competition among privately-issued fiat currencies work? Only sometimes and partially. To show this, we build a model of competition among privately-issued fiat currencies. A purely private arrangement fails to implement an efficient allocation, even though it can deliver price stability under certain technological conditions. Although currency competition creates problems for monetary policy, it is possible to design a policy rule that uniquely implements an efficient allocation.

• Banking Panics and Output Dynamics

           Review of Economic Dynamics  volume 29 (2018), pp. 148-171

Abstract: This paper develops a dynamic general equilibrium model with an essential role for an illiquid banking system to investigate output dynamics in the event of a banking crisis. In particular, it considers the ex-post efficient policy response to a banking crisis as part of the dynamic equilibrium analysis. It is shown that the trajectory of real output following a panic episode crucially depends on the cost of converting long-term assets into liquid funds. For small values of the liquidation cost, the recession associated with a banking panic is protracted as a result of the premature liquidation of a large fraction of productive banking assets to respond to a panic. For intermediate values, the recession is more severe but short-lived. For relatively large values, the contemporaneous decline in real output in the event of a panic is substantial but followed by a vigorous rebound in real activity above the long-run level.

• On the Welfare Properties of Fractional Reserve Banking

          International Economic Review  volume 57 (2016), pp. 935-954

Abstract: Monetary economists have long recognized a tension between the benefits of fractional reserve banking, such as the ability to undertake more profitable (long‐term) investment opportunities, and the difficulties associated with it, such as the risk of insolvency for each bank and the associated losses to bank liability holders. I show that a specific banking arrangement (a joint‐liability scheme) provides an effective mechanism for ensuring the ex post transfer of reserves from liquid banks to illiquid banks, so it is possible to select a socially efficient reserve ratio in the banking system that preserves the safety of bank liabilities as a store of value and maximizes the rate of return paid to bank liability holders. 

• On the Inherent Instability of Private Money

         Review of Economic Dynamics  volume 20 (2016), pp. 198-214

Abstract: A primary concern in monetary economics is whether a purely private monetary regime is consistent with macroeconomic stability. I show that a competitive regime is inherently unstable due to the properties of endogenously determined limits on private money creation. Precisely, there is a continuum of equilibria characterized by a self-fulfilling collapse of the value of private money and a persistent decline in the demand for money. I associate these equilibrium allocations with self-fulfilling banking crises. It is possible to formulate a fiscal intervention that results in the global determinacy of equilibrium, with the property that the value of private money remains stable. Thus, the goal of monetary stability necessarily requires some form of government intervention.

• Private Money and Banking Regulation (with Cyril Monnet)

         Journal of Money, Credit and Banking  volume 47 (2015), pp. 1031-1062

Abstract: We show that a competitive banking system is inconsistent with an optimum quantity of private money. Because bankers cannot commit to their promises and the composition of their assets is not publicly observable, a positive franchise value is required to induce the full convertibility of bank liabilities. Under perfect competition, a positive franchise value can be obtained only if the return on bank liabilities is sufficiently low, which imposes a cost on those who hold these liabilities for transaction purposes. If the banking system is monopolistic, then an efficient allocation is incentive feasible. In this case, the members of the banking system obtain a higher return on assets, making it feasible to pay a sufficiently high return on bank liabilities. Finally, we argue that the regulation of the banking system is required to obtain efficiency.

• Optimal Monetary Policy in a Model of Money and Credit (with Pedro Gomis-Porqueras)

         Journal of Money, Credit and Banking  volume 45 (2013), pp. 701-730

Abstract: We investigate the extent to which monetary policy can enhance the functioning of the private credit system. Specifically, we characterize the optimal return on money in the presence of credit arrangements. There is a dual role for credit: it allows buyers to trade without fiat money and also permits them to borrow against future income. However, not all traders have access to credit. As a result, there is a social role for fiat money because it allows agents to self‐insure against the risk of not being able to use credit in some transactions. We consider a (nonlinear) monetary mechanism that is designed to enhance the credit system. An active monetary policy is sufficient for relaxing credit constraints. Finally, we characterize the optimal monetary policy and show that it necessarily entails a positive inflation rate.

• A Dynamic Model of Unsecured Credit

         Journal of Economic Theory  volume 146 (2011), pp. 1941-1964

Abstract: I study the terms of credit in a competitive market in which sellers (lenders) are willing to repeatedly finance the purchases of buyers (borrowers) by engaging in a credit relationship. The key frictions are: (i) the lender cannot observe the borrower's ability to repay a loan; (ii) the borrower cannot commit to any long-term contract; (iii) it is costly for the lender to contact a borrower and to walk away from a contract; and (iv) transactions within each credit relationship are not publicly observable. The lender's optimal contract has two key properties: delayed settlement and debt forgiveness. Finally, I study the impact of changes in the initial cost of lending on the contract terms.

• Adverse Selection, Segmented Markets, and the Role of Monetary Policy (with Stephen Williamson)

         Macroeconomic Dynamics  volume 15, Supplement No. 2 (2011), pp.269-292

Abstract: A model is constructed in which trading partners are asymmetrically informed about future trading opportunities and spatial and informational frictions limit arbitrage between markets. These frictions create inefficiency relative to a full-information equilibrium, and the extent of this inefficiency is affected by monetary policy. A Friedman rule is optimal under a wide range of circumstances, including ones where segmented markets limit the extent of monetary policy intervention.

• Money and Credit with Limited Commitment and Theft (with Stephen Williamson)

        Journal of Economic Theory  volume 145 (2010), pp. 1525-1549

Abstract: We study the interplay among imperfect memory, limited commitment, and theft, in an environment that can support monetary exchange and credit. Imperfect memory makes money useful, but it also permits theft to go undetected, and therefore provides lucrative opportunities for thieves. Limited commitment constrains credit arrangements, and the constraints tend to tighten with imperfect memory, as this mitigates punishment for bad behavior in the credit market. Theft matters for optimal monetary policy, but at the optimum theft will not be observed in the model. The Friedman rule is in general not optimal with theft, and the optimal money growth rate tends to rise as the cost of theft falls.