# 2009

09-01. Dávila, J., Eeckhout, J., y C. Martinelli.,* "Bargaining over Public Goods" *

**Resumen: **In a simple public good economy, we propose a natural bargaining procedure whose equilibria converge to Lindahl allocations as the cost of bargaining vanishes. The procedure splits the decision over the allocation in a decision about personalized prices and a decision about output levels for the public good. Since this procedure does not assume price-taking behavior, it provides a strategic foundation for the personalized taxes inherent to the Lindahl solution to the public goods problem.

09-02. Chatterji, S., y I. Lobato., "*Transformations of the State Variable and Learning Dynamics"*

**Resumen:** This article studies dynamics in a model where agents forecast a one dimensional state variable via ordinary least squares regressions on the lagged values of the state variable. We study the stability properties of alternative transformations of the state variable that the agent can endogenously set forth. We study the consequences on the economy's stability of the typical transformations that an econometrician would attempt, such as differencing, detrending, or taking instantaneous concave transformations, such as logarithms. Surprisingly, for the considered class of economies, we found that these transformations are destabilizing, whereas alternative transformations, which an econometrician would never consider, such as convex transformations, are stabilizing. Therefore, we ironically find that in our set-up, an active agent, who is concerned about learning the economy's dynamics and, in an attempt to improve forecasting, transforms the state variable using the standard transformations, is more likely to deviate from the steady state than a passive agent.

09-03. Ulku, L.,* "Optimal Combinatorial Mechanism Design"*

**Resumen:** We consider an optimal mechanism design problem with several heterogeneous objects and interdependent values. We characterize ex post incentives using an appropriate monotonicity condition and reformulate the problem in such a way that the choice of an allocation rule can be separated from the choice of the payment rule. Central to our analysis is the formulation of a regularity condition, which gives a recipe for the optimal mechanism. If the problem is regular, then an optimal mechanism can be obtained by solving a combinatorial allocation problem in which objects are allocated in a way to maximize the sum of "virtual" valuations. We identify conditions that imply regularity for two nonnested environments using the techniques of supermodular optimization.

09-04. Vadovic, R., *"Early, Late, and Multiple Bidding in Internet Auctions" *

**Resumen:** In Internet auctions bidders frequently bid in one of three ways: either only early, or late, or they revise their early bids. This paper rationalizes all three bidding patterns within a single equilibrium. We consider a model of a dynamic auction in which bidders can search for outside prices during the auction. We find that in the equilibrium bidders with the low search costs bid only late and always search, while the bidders with high search costs bid early or multiple times and search only if they were previously outbid. An important feature of the equilibrium is that early bidding allows bidders to search in a coordinated manner. This means that everyone searches except the bidder with the highest early bid. We also compare the static and dynamic auction and conclude that dynamic auction is always more efficient but not always more profitable.

09-05. Melissas, N., *"On Bid Disclosure in OCS Wildcat Auctions" *

**Resumen:** I study a game in which two players first bid for offshore tracts (below which oil and gas may be present) and next time their drilling decisions. High types bid more aggressively if the auctioneer discloses bids as this gives them useful information about the profitability of drilling. A low type fears that the disclosure of her "low" bid reduces the other player's incentive to drill. Hence, they bid more aggressively if the auctioneer does not disclose bids. If players are sufficiently patient, it is optimal to disclose bids. Otherwise, it may be optimal not to disclose them.

09-06. Lizarazo, S., *"Contagion of Financial Crises in Sovereign Debt Markets"*

**Resumen: **This paper develops a quantitative model of debt, default, and contagion of financial crises for small open economies that interact with risk averse international investors. The paper extends the recent literature on endogenous default risk to the case in which several emerging economies that cannot credibly commit to honor their international debts have common investors. The existence of common investors with preferences that exhibit decreasing absolute risk aversion generates financial links between the emerging economies sovereign debt markets that help to explain the endogenous determination of credit limits, capital flows, and the risk premium in sovereign bond prices as function not only of the economy's fundamentals, the investors' characteristics (wealth, and degree of risk aversion) but more importantly of the fundamentals of other emerging economies. Therefore this paper provides a theoretical formalization that is the base for and endogenous explanation of the contagion of financial crises.

09-07. Lizarazo, S., *"Default Risk and Risk Averse International Investors" *

**Resumen:** This paper develops a quantitative model of debt and default for small open economies that interact with risk averse international investors. The model developed here extends the recent work on the analysis of endogenous default risk to the case in which interna- tional investors are risk averse agents with decreasing absolute risk aversion (DARA). By incorporating risk averse investors who trade with a single emerging economy, the present model oers two main improvements over the standard case of risk neutral investors: i.) the model exhibits a better fit of debt-to-output ratio and ii.) the model explains a larger proportion and volatility of the spread between sovereign bonds and riskless assets. The paper shows that if investors have DARA preferences, then the emerging economy's default risk, capital flows, bond prices and consumption are a function not only of the fundamentals of the economy -as in the case of risk neutral investors- but also of the level of financial wealth and risk aversion of the international investors. In particular, as investors become wealthier or less risk averse, the emerging economy becomes less credit constrained. As a result, the emerging economy's default risk is lower, and its bond prices and capital inflows are higher. Additionally, with risk averse investors, the risk premium in the asset prices of the sovereign countries can be decomposed into two components: a base premium that compensates the investors for the probability of default (as in the risk neutral case) and an "excess" premium that compensates them for taking the risk of default.

09-08. Da-Rocha, J.M., y S. Lizarazo., *"Money, Credit and Default" *

**Resumen:** This paper develops a quantitative model of unsecured debt, default, and money demand for heterogenous agents economies. The paper generates a theory of money demand for the case in which money is a dominate asset that is not needed to carry-out transactions. In this environment holding money helps the agents to smooth their consumption during those periods in which they are excluded from credit markets following a default in their debts. In the model the welfare of the individuals is affected by the inflation rate: high inflation rates preclude individuals of using money as an asset that helps them smooth their consumption profile but low inflation rates tend to make softer the punishment for default making it dificult to sustain high levels of debt at equilibrium. This two opposite effects imply that in equilibrium the inflation rate that maximizes individuals welfare is positive but not too high.

09-09. Iraola, M. A., y M. S. Santos., *"Long-Term Asset Price Volatility and Macroeconomic Fluctuations" *

**Resumen:** We analyze a stochastic growth model with lags in the operation of new technologies. Stock values are impacted by news on technological innovations and some other external shocks affecting the economy. Episodes of technology adoption may generate long fluctuations in the aggregate value of stocks. We asses the quantitative importance of various macroeconomic variables in accounting for both the observed volatility of stock values and the less pronounced volatility of real macroeconomic aggregates. Our analysis singles out price markups and leverage as key determinants of asset price volatility, and confers a rather limited role to adjustment costs, taxes, and labor and financial frictions.