Publications

Collateralizing Liquidity**,  Journal of Financial Economics, 131 (2019), pp. 299-322
I develop a dynamic model of optimal funding to understand why financial assets are used as collateral instead of being sold to raise funds. Firms need funds to invest in risky projects with non-observable returns. Since holding these assets allows firms to raise these funds, investing firms value the asset more than non-investing ones. When assets are less than perfectly liquid and investment opportunities are persistent, collateralized debt minimizes asset transfers from investing to non-investing firms and, thus, is optimal. Frictions in asset markets lead to an illiquidity discount and a collateral premium, which increase with the asset's illiquidity.​

**Previously titled " Equilibrium Collateral Constraints".
Fragility in Money Market Funds: Sponsor Support and Regulation*,  Journal of Financial Economics 121 (2016), pp. 595-623
Money Market Funds (MMFs), which are crucial to short-term funding markets, rely on voluntary support of fund sponsors to maintain stable share values. I develop a general equilibrium model of MMFs to study how sponsor support affects the industry’s fragility and regulation. Adverse asset-quality shocks lead MMFs to liquidate assets. When liquidity in asset markets is limited, asset prices are lower if more funds liquidate. Lower asset prices, in turn, make sponsor support costlier and even more liquidations occur. This feedback leads to complementarities in sponsors’ support decisions. Based on the model’s insights, I derive implications for the regulation of MMFs.                                                                                                                                                                
                                                                                                                                                                                                                                     [Presentation UWFC]
* Previously titled "The Regulation of Money Market Funds: Adding Discipline to the Policy Debate".  
Modernization of Tax Administrations and Optimal Fiscal Policies ​with Martin Besfamille, Journal of Public Economic Theory 11 (6), 2009, 897 - 926, December 
Since Sandmo (1981), many articles have analyzed optimal fiscal policies in economies with tax evasion. All share a feature: they assume that the cost of enforcing the tax law is exogenous. However, governments often invest resources to reduce these enforcement costs. In a very simple model, we incorporate such investments in the analysis of an optimal fiscal policy. We characterize their optimal level and we show numerically how they interact with the other dimensions of the optimal fiscal policy. Finally, we highlight the differences between our results and those obtained in a model without investment in the tax administration. 

Working papers

Identifying Price Informativeness with Eduardo Dávila                                                                                                                                               October 2018
​We show that outcomes (parameter estimates and R-squareds) of regressions of prices on fundamentals allow us to recover exact measures of the ability of asset prices to aggregate dispersed information. Formally, we show how to recover absolute and relative price informativeness in dynamic environments with rich heterogeneity across investors (regarding signals, private trading needs, or preferences), minimal distributional assumptions, multiple risky assets, and allowing for stationary and non-stationary asset payoffs. We implement our methodology empirically, finding stock-specific measures of price informativeness for U.S. stocks. We find a right-skewed distribution of price informativeness, measured in the form of the Kalman gain used by an external observer that conditions its posterior belief on the asset price. The recovered mean and median are 0.05 and 0.02 respectively. We find that price informativeness is higher for stocks with higher market capitalization and higher trading volume.
​Volatility and Informativeness with Eduardo Dávila                                                                                                                                                December 2018
We explore the equilibrium relation between price volatility and price informativeness in financial markets, with the ultimate goal of characterizing the type of inferences that can be drawn about price informativeness by observing price volatility. We identify two different channels (noise reduction and equilibrium learning) through which changes in price informativeness are associated with changes in price volatility. We show that when informativeness is sufficiently high (low) volatility and informativeness positively (negatively) comove in equilibrium for any change in primitives. In the context of our leading application, we provide conditions on primitives that guarantee that volatility and informativeness always comove positively or negatively. We use data on U.S. stocks between 1963 and 2017 to recover stock-specific primitives and find that most stocks lie in the region of the parameter space in which informativeness and volatility comove negatively.
Trading Costs and Informational Efficiency with Eduardo Dávila                                                                                                                               March  2019
We study the effect of trading costs on information aggregation and acquisition in financial markets. For a given precision of investors' private information, an irrelevance result emerges when investors are ex-ante identical: price informativeness is independent of the level of trading costs. When investors are ex-ante heterogeneous, anything goes, and a change in trading costs can increase or decrease price informativeness, depending on the source of heterogeneity. Our results are valid under quadratic, linear, and fixed costs. Through a reduction in information acquisition, trading costs reduce price informativeness. We discuss how our results inform the policy debate on financial transaction taxes/Tobin taxes. 
Designing Stress Scenarios with Thomas Philippon (draft coming soon)​                                                                                                                          April 2019
We develop a tractable framework to study the optimal design stress scenarios. A risk-averse principal (e.g, a manager, a regulator) seeks to learn about the exposures of a group of agents (e.g., traders, banks) to a set of risk factors. The principal asks the agents to report their outcomes (e.g., credit losses) under a variety of scenarios that she designs. She can then take remedial actions (e.g., mandate reductions in risk exposures). The principal's program has of two parts. For a given set of scenarios, we show how to apply a Kalman filter to solve the learning problem. The optimal design is then a function of what she wants to learn and how she intends to intervene if she uncovers excessive exposures. The choice of optimal scenarios depends on the principal's prior's about risk exposures, the cost of ex-post interventions, and the potential correlation of exposures across agents.
Strategic Fragmented Markets with Ana Babus                                                                                                                                                              January 2018
We study the determinants of asset market fragmentation. We develop a model of market formation with strategic investors that have heterogeneous valuations for an asset. Investors choose a dealer with whom to trade considering their price impact and the liquidity provided by the dealer. Fragmented markets are supported in equilibrium when investors' valuations are sufficiently correlated. In this case, liquidity provision is scarce and investors are more willing to accept a higher price impact. The maximum degree of market fragmentation is determined by dealer entry, and increases as investors' valuations are more correlated. Dealers can benefit from fragmentation, but investors are always better off in centralized markets. 
​Transparency and Bank Runs                                                                                                                                                                                                   April 2015
In a banking model with imperfect information, I find that more precise information increases the economy's vulnerability to bank runs. For low transparency levels, depositors cannot distinguish bad from good states based on their private signals and, absent liquidity shocks, have no incentives to withdraw early. As transparency increases, and private signals become more informative, depositors' incentives to withdraw strengthen and run-proof contracts become costlier in risk-sharing terms: the bank must offer less to early withdrawers to prevent runs. When transparency is high enough, the bank would rather forgo return and hold excess liquidity than choose a run-proof deposit contract.

Work in progress

The Value of Arbitrage with Eduardo Dávila