Stationary monetary equilibria with strictly increasing value functions and non-discrete money holdings distributions: An indeterminacy result

In this paper, we present a search model with divisible money in which there exists a continuum of monetary equilibria with strictly increasing continuous value functions and with non-discrete money holdings distributions.     

Substitutes and stability for matching with contracts

We consider the matching with contracts framework of Hatfield and Milgrom [20], and we introduce new concepts of bilateral and unilateral substitutes. We show that the bilateral substitutes condition is a sufficient condition for the existence of a stable allocation in this framework. However, the set of stable allocations does not form a lattice under this condition, and there does not necessarily exist a doctor-optimal stable allocation. Under a slightly stronger condition, unilateral substitutes, the set of stable allocations still does not necessarily form a lattice with respect to doctors' preferences, but there does exist a doctor-optimal stable allocation, and other key results such as incentive compatibility and the rural hospitals theorem are recovered.     

Informational limitations of ascending combinatorial auctions

We study the inherent limitations of natural widely-used classes of ascending combinatorial auctions. Specifically, we show that ascending combinatorial auctions that do not use both non-linear prices and personalized prices cannot achieve social efficiency with general bidder valuations. We also show that the loss of efficiency can be severe and that only a diminishing fraction of the social welfare may be captured. This justifies the added complexity in the auctions suggested by, e.g., Parkes and Ungar (2000) [29] and Ausubel and Milgrom (2002) [2].     

Efficient propagation of shocks and the optimal return on money

We study optimal allocations in an environment in which money is essential due to lack of commitment and anonymity of individuals. Because the economy features aggregate preference shocks, we apply a notion of implementability that allows for allocations with non-trivial business-cycle dynamics for the propagation of shocks. We show that history dependence is predicted by the theory of second best and becomes necessary for optimality when the degree of patience is neither too low nor too high. Our analysis concludes with a discussion of whether there is a role for the propagation of shocks in alternative economic environments.     

Bidding for the future: signaling in auctions with an aftermarket

This paper considers auctions where bidders compete for an advantage in future strategic interactions. When bidders wish to exaggerate their private information, equilibrium bidding functions are biased upwards as bidders attempt to signal via the winning bid. Signaling is most prominent in second-price auctions where equilibrium bids are “above value.” In English and first-price auctions, signaling is less extreme since the winner incurs the cost of her signaling choice. The opportunity to signal lowers bidders’ payoffs and raises revenue. When bidders understate their private information, separating equilibria need not exist and the auction may not be efficient.     

Trading horizons and the value of money

This paper shows that fiat money can be feasible and essential even if the trading horizon is finite and deterministic. The result hinges on two features of our model. First, individual actions can affect the future availability of productive resources. So, agents may be willing to sell for money, even if on that date they have no reason to accept it. This makes monetary trade feasible in all preceding dates. Second, agents are anonymous and direct their search for partners. So, gift-giving arrangements may be prevented because agents can misrepresent their consumption needs. This makes money essential in exploiting any gains from specialization and trade.     

Measuring stress in money markets: A dynamic factor approach

We extract an index of interest rate spreads from various money market segments to assess the level of funding stress in real time. We find that during the 2007–2009 financial crisis, money markets switched between low and high stress regimes except for brief periods of extreme stress. Transitions to lower stress regimes are typically associated with the non-standard policy measures by the Federal Reserve.     

The Relationship between Australian Mutual Fund Fees and Risk‐Adjusted Performance in Differing Economic Conditions

We find that Australian mutual fund investors should avoid high fee funds as these funds generate relatively low after‐fee risk‐adjusted returns both unconditionally and in weak economic conditions. This result is different from some of the previous findings which showed that US mutual funds with relatively high expense ratios may generate relatively higher risk‐adjusted returns during recessions relative to non‐recessions, although their unconditional alphas may be negative. We find some support for the Glode hypothesis in surviving Australian wholesale funds. High‐fee surviving Australian wholesale funds perform relatively strongly in both weak economic conditions and unconditionally. High‐fee funds in other types of Australian mutual funds generally do not perform strongly either in weak economic conditions or unconditionally. Amongst low‐fee funds, we commonly find that those that perform well unconditionally and well in weak economic conditions do charge more than those that perform well unconditionally and poorly in weak economic conditions. Amongst low‐fee funds, it is often true that those that perform poorly unconditionally but well in weak economic conditions can charge more than those that perform poorly unconditionally and poorly in weak economic conditions.     

Does commodity money eliminate the indeterminacy of equilibrium?

Previous studies have shown that a random-matching model with divisible fiat money and without constraint on agents’ money inventories possesses a continuum of stationary single-price equilibria. Wallace (J. Econom. Theory 81 (1998) 223) conjectures that the indeterminacy can be eliminated by the use of commodity money. Instead, I find that in a similar random-matching model with dividend-yielding commodity money, a continuum of stationary single-price equilibria exists when the utility of dividend is not too high. This result casts doubt on the conventional belief that the indeterminacy of monetary equilibrium is be caused only by the nominal nature of money.     

Bidding behavior in asymmetric auctions: An experimental study

We review an asymmetric auction experiment. Based on Plum (Int. J. Game Theory 20 (1992) 393) private valuations of the two bidders are independently drawn from distinct but commonly known distributions, one of which first-order stochastically dominates the other. We test the qualitative properties of that model of asymmetric auctions, in particular whether the weak bidder behaves more aggressively than the strong, and then test bidders’ preference for first- vs. second-price auctions.     

Bargaining and inequity aversion: On the efficiency of the double auction

In a bargaining setting with asymmetrically informed, inequity-averse parties, a fully efficient mechanism (i.e., the double auction) exists if and only if compassion is strong. Less compassionate parties do not trade in the double auction in the limit of strong envy.     

Matching through position auctions

Using a mechanism design framework, we characterize how a profit-maximizing intermediary can design matching markets when each agent is privately informed about his quality as a partner. Sufficient conditions are provided that ensure a version of positive assortative matching (what we call truncated positive assortative matching) maximizes profits. Under these conditions, all-pay position auctions always implement the profit-maximizing allocation. Winners-pay position auctions, however, only do so in sufficiently large markets.     

Sorting versus screening: Search frictions and competing mechanisms

In a market where sellers compete by posting trading mechanisms, we allow for a general search technology and show that its features crucially affect the equilibrium mechanism. Price posting prevails when meetings are rival, i.e., when a meeting by one buyer reduces another buyer's meeting probability. Under price posting buyers reveal their type by sorting ex-ante. Only if the meeting technology is sufficiently non-rival, price posting is not an equilibrium. Multiple buyer types then visit the same sellers who screen ex-post through auctions.     

Cumulative offer process is order-independent

This note shows that in the matching-with contracts model, the outcome of the cumulative offer process is order-independent if every hospital has a choice function that satisfies the bilateral substitutability condition and the irrelevance of rejected contracts condition.     

Incentives to produce quality and the liquidity of money

Summary I study a version of the Williamson-Wright (1994) model that results from ruling out direct barter. Although one can no longer argue that the value of money comes exclusively from private information, one can use the simplified model to address a variety of other issues. In particular, one can characterize analytically the set of equilibria and their properties. One can also analyze the trade-off between providing liquidity to facilitate trade and providing incentives to produce high quality, and address some other issues related to policy and welfare, including the effects of inflation on the incentives to produce high quality.I am grateful to Faruk Gul, Yiting Li, Nicholas Yannelis, an anonimous referee and especially Randall Wright for their input.     

Group robust stability in matching markets

We introduce the notion of group robust stability which requires robustness against a combined manipulation, first misreporting preferences and then rematching, by any group of students in the school choice type of matching markets. Our first result shows that there is no group robustly stable mechanism even under acyclic priority structures. Next, we define a weak version of group robust stability, called weak group robust stability. Our main theorem, then, proves that there is a weakly group robustly stable mechanism if and only if the priority structure of schools is acyclic, and in that case, it coincides with the student-optimal stable mechanism.     

On the coexistence of money and higher-return assets and its social role

This paper adopts mechanism design to investigate the coexistence of fiat money and higher-return assets. We consider an economy with pairwise meetings where fiat money and risk-free capital compete as means of payment, as in [28]. The trading mechanism in pairwise meetings is chosen among all individually rational, renegotiation-proof mechanisms to maximize society?s welfare. We show that in any stationary monetary equilibrium capital commands a higher rate of return than fiat money.     

Incomplete information and singleton cores in matching markets

We study ordinal Bayesian Nash equilibria of stable mechanisms in centralized matching markets under incomplete information. We show that truth-telling is an ordinal Bayesian Nash equilibrium of the revelation game induced by a common belief and a stable mechanism if and only if all the profiles in the support of the common belief have singleton cores. Our result matches the observations of Roth and Peranson [The redesign of the matching market for American physicians: some engineering aspects of economic design, Amer. Econ. Rev. 89 (1999) 748-780] in the National Resident Matching Program (NRMP) in the United States: (i) the cores of the profiles submitted to the clearinghouse are small and (ii) while truth-telling is not a dominant strategy most participants in the NRMP truthfully reveal their preferences.     

Macroeconomic fluctuations and bargaining

I study the limit rule for bilateral bargaining when agents recognize that the aggregate economy (and thus the match surplus) follows a finite-state Poisson process. The rule derived in this paper is of special importance for decentralized exchange economies with bargaining. Two simple applications are presented to illustrate this fact. The first example is a model of wage bargaining and trade externalities. I show that in such situations sophisticated bargaining tends to increase the volatility of the wage bill. The second example is based on the Kiyotaki-Wright model of money. I explain how equilibrium prices depend in a fundamental way on the dynamic bargaining solution.     

ON DETAIL‐FREE MECHANISM DESIGN AND RATIONALITY*

Mechanism design theory has been criticized, because mechanisms depend on the detail of specification and agents’ behaviour relies on strong rationality assumptions. Hence the study of “detail‐free” mechanism design with weak rationality is important as a practical theory. This paper emphasizes that, even if we confine our attention to detail‐free mechanisms with weak rationality, there exists plenty of scope for the development of new and significant ideas. I describe my recent work along these lines, and argue that stochastic decisions work in large double auction environments, and that moral preferences improve the implementability of social choice functions.