Pierre-Olivier Weill

Leaning Against the Wind

During financial disruptions, market makers provide liquidity by absorbing external selling pressure. They buy when the pressure is large, accumulate inventories, and sell when the pressure alleviates. This paper studies optimal dynamic liquidity provision in a theoretical market setting with large and temporary selling pressure and order-execution delays. I show that competitive market makers offer the socially optimal amount of liquidity, provided they have access to sufficient capital. If raising capital is costly, this suggests a policy role for lenient central bank lending during financial disruptions. Copyright 2007, Wiley-Blackwell.

Learning from Prices: Public Communication and Welfare

We study the effect of releasing public information about productivity or monetary shocks using a micro-founded macroeconomic model in which agents learn from the distribution of nominal prices. While a public release has the direct beneficial effect of providing new information, it also has the indirect adverse effect of reducing the informational efficiency of the price system. We show that the negative indirect effect can dominate. Thus, the public information release may increase uncertainty about the monetary shock and reduce welfare. We find that the optimal communication policy is always to release either all or none of the information.

Crises and liquidity in over-the-counter markets

We study the efficiency of liquidity provision by dealers and the desirability of policy intervention in over-the-counter (OTC) markets during crises. We emphasizes two OTC frictions: finding counterparties takes time, and trade is bilateral and involves bargaining. We model a crisis as a shock that reduces investorsʼ asset demands, lasting until a random recovery time. In this context, dealers can provide liquidity to investors by accumulating asset inventories. When OTC frictions are severe, even well capitalized dealers may not find it privately optimal to accumulate inventories, and direct purchase by the government can improve welfare.

Learning from private and public observations of othersʼ actions

We study how a continuum of agents learn about disseminated information by observing others’ actions. Every period each agent observes a public and private noisy signal centered around the aggregate action taken by the population. The public signal represents an endogenous aggregate variable such as a price or a quantity. The private signal represents the information gathered through private communication and local interactions. We identify conditions such that the average learning curve is S-shaped: learning is slow initially, intensifies rapidly, and finally converges slowly to the truth. We show that increasing public information always slows down learning in the long run and, under some conditions, reduces welfare. Lastly, optimal diffusion of information requires that agents “strive to be different”: agents need to be rewarded for choosing actions away from the population average.

Liquidity and the Threat of Fraudulent Assets

We study an over-the-counter (OTC) market in which the usefulness of assets as a means of payment or collateral is limited by the threat of fraudulent practices. Agents can produce fraudulent assets at a positive cost, which generates upper bounds on the quantity of each asset that can be traded in the OTC market. Each of these endogenous, asset-specific, resalability constraints depends on the cost of fraud, on the frequency of trade, and on the asset price. In equilibrium, assets are partitioned into three liquidity tiers, which differ in their resalability, prices, haircuts, sensitivity to shocks, and responses to policies.

Why Has House Price Dispersion Gone Up

We investigate the 30 year increase in the level and dispersion of house prices across U.S. metropolitan areas in a calibrated dynamic general equilibrium island model. The model is based on two main assumptions: households flow in and out metropolitan areas in response to local wage shocks, and the housing supply cannot adjust instantly because of regulatory constraints. Feeding in our model the 30 year increase in cross-sectional wage dispersion that we document based on metropolitan-level data, we generate the observed increase in house price level and dispersion. In equilibrium, workers flow towards exceptionally productive metropolitan areas and drive house prices up. The calibration also reveals that, while a baseline level of regulation is important, a tightening of regulation by itself cannot account for the increase in house price level and dispersion: in equilibrium, workers flow out of tightly regulated towards less regulated metropolitan areas, undoing most of the price impact of additional local supply regulations. Finally, the calibration with increasing wage dispersion suggests that the welfare effects of housing supply regulation are large.

Liquidity in Frictional Asset Markets

On November 14-15, 2008, the Federal Reserve Bank of Cleveland hosted a conference on “Liquidity in Frictional Asset Markets.” In this paper we review the literature on asset markets with trading frictions in both finance and monetary theory using a simple search-theoretic model, and we discuss the papers presented at the conference in the context of this literature. We will show the diversity of topics covered in this literature, e.g., the dynamics of housing and credit markets, the functioning of payment systems, optimal monetary policy and the cost of inflation, the role of banks, the effect of informational frictions on asset trading.

Crashes and Recoveries in Illiquid Markets

We study the dynamics of liquidity provision by dealers during an asset market crash, described as a temporary negative shock to investors aggregate asset demand. We consider a class of dynamic market settings where dealers can trade continuously with each other, while trading between dealers and investors is subject to delays and involves bargaining. We derive conditions on fundamentals, such as preferences, market structure and the characteristics of the market crash (e.g., severity, persistence) under which dealers provide liquidity to investors following the crash. We also characterize the conditions under which dealers incentives to provide liquidity are consistent with market efficiency.

Liquidity Shocks and Order Book Dynamics

We propose a dynamic competitive equilibrium model of limit order trading, based on the premise that investors cannot monitor markets continuously. We study how limit order markets absorb transient liquidity shocks, which occur when a significant fraction of investors lose their willingness and ability to hold assets. We characterize the equilibrium dynamics of market prices, bid-ask spreads, order submissions and cancelations, as well as the volume and limit order book depth they generate.

Heterogeneity in Decentralized Asset Markets

We study a search and bargaining model of an asset market, where investors’ heterogeneous valuations for the asset are drawn from an arbitrary distribution. Our solution technique renders the analysis fully tractable and allows us to provide a full characterization of the equilibrium, in closed-form, both in and out of steady-state. We use this characterization for two purposes. First, we establish that the model can naturally account for a number of stylized facts that have been documented in empirical studies of over-the-counter asset markets. In particular, we show that heterogeneity among market participants implies that assets are reallocated through “intermediation chains,�? ultimately producing a core-periphery trading network and non-trivial distributions of prices and trading times. Second, we show that the model generates a number of novel results that underscore the importance of heterogeneity in decentralized markets. We highlight two: First, heterogeneity magnifies the price impact of search frictions; and second, search frictions have larger effects on price levels than on price dispersion. Hence, quantifying the price discount or premium created by search frictions based on observed price dispersion can be misleading.