Negative Externalities and Evolutionary Implementation

We model externality abatement as an implementation problem. A social planner would like to ensure efficient behaviour among a group of agents whose actions are sources of externalities. However, the planner has limited information about the agents' preferences, and is unable to distinguish individual agents except through their action choices. We prove that if a concavity condition on aggregate payoffs is satisfied, the planner can guarantee that efficient behaviour is globally stable under a wide range of behaviour adjustment processes by administering a variable pricing scheme. Through a series of applications, we show that the concavity condition is naturally satisfied in settings involving negative externalities. We conclude by contrasting the performance of the pricing mechanism with that of a mechanism based on direct revelation and announcement dependent forcing contracts.     

A Case for Bundling Public Goods Contributions

We extend the model of voluntary contributions to multiple public goods by allowing for bundling of the public goods. Specifically, we study the case where agents contribute into a common pool which is then allocated toward the financing of two pure public goods. We explore the welfare implications of allowing for such bundling vis‐à‐vis a separate contributions scheme. We show that for high income inequality or for identical preferences among agents bundling leads to higher joint welfare. Interestingly, a welfare improvement can in some cases occur despite a decrease in total contributions. On the contrary, when agents are heterogenous, for low income inequality bundling can lead to lower total contributions and may decrease welfare compared to a separate contribution scheme. Our findings have implications for the design of charitable institutions and international aid agencies.     

An additional explanation for the variable Keynesian multiplier: The role of the propensity to import

This article analyzes the concept of the Keynesian multiplier from a new perspective. Several recent studies have shown that the fiscal multiplier is endogenous to the level of economic activity, increasing during recessions and decreasing during the boom. Here, we provide some evidence, explaining this variability over the business cycle, based on the overreaction of aggregate imports. Then, we apply the concept of endogenous propensity to import, varying with capacity utilization, to a neo-Kaleckian model of growth and distribution. We perform some simple simulations showing that the Keynesian multiplier increases during a recession, which logically does not advocate a reduction in public spending when the economy is in crisis.     

The relative contributions of private information sharing and public information releases to information aggregation

We calculate learning rates when agents are informed through public and private observation of other agents' actions. We characterize the evolution of the distribution of posterior beliefs. If the private learning channel is present, convergence of the distribution of beliefs to the perfect-information limit is exponential at a rate equal to the sum of the mean arrival rate of public information and the mean rate at which individual agents are randomly matched with other agents. If, however, there is no private information sharing, then convergence is exponential at a rate strictly lower than the mean arrival rate of public information.     

中国证券市场反应偏差的研究——基于股票股利的实证研究

采用1998年-2004年的A股上市公司作为样本,试图从行为金融的角度出发,立足于反应偏差的研究,对股票股利的股价效应厦反应偏差演变进行研究,包含即对股票股利公告后股价在二级市场的反应以厦从纵向的角度来看,分析反应偏差程度的演变规律。研究发现：对于股票股利公告在公告的当天对股票价格产生显著的正超额收益率,并且对于股票股利公告普遍存在反应偏差,反应偏差度也随着时间的推移逐步明显减小。     

股票市场上利率政策公告效应实证研究

货币政策信息作为一种对整个市场或者整个行业都产生影响的宏观信息以及同时为市场参与者获知的公共信息,其信息的公布必将对股票市场的价格行为产生影响。把利率政策作为货币政策信息的代表,可以用来测度利率政策公告的即期效应,借鉴这样的思路,我们选用事件研究法方法来研究我国存贷款利率调整对股票市场的公告效应,发现存贷款利率调整宣告会对股票市场的价格和波动产生显著的影响,但利率调整宣告对股票市场的影响并不确定。     

Decentralizing Allocation and Distribution by Separation with Information Transfers

Governments often divide operations into separate branches that face different constraints and have limited information. Such separation is feasible if each can operate by solving a simple optimization problem using limited information without requiring game-theoretic calculations about others' actions. We specify two structures of one-way information transfers that allow this. For each structure, we present conditions for unified and decentralized decision-making to have identical outcomes. One of them corresponds to using a Samuelson aggregate welfare function that is not always fully efficient. We apply our results to several examples, including public goods and Ramsey pricing.     

The Role of Industry Effects in Simultaneous Reversal and Momentum Patterns in One-Month Stock Returns

When stocks are ranked by returns in one month, the portfolio of loser stocks tends to outperform the portfolio of winner stocks in the subsequent month. Yet industry portfolios tend to display momentum. We develop a model of information diffusion among agents with constrained information processing ability that reconciles these well-documented phenomena. We test whether this model or the overreaction hypothesis is consistent with the data. Additionally, a trading strategy based on the model outperforms strategies based on overreaction and on industry momentum. The strategy produces abnormal returns while controlling for market–risk and the size, book value, January, momentum, and liquidity effects.     

Reducing Inefficiency in Public Good Provision Through Linking

We characterize the optimal mechanism for the provision of n public goods in an economy with m agents, binary valuations. The mechanism “links” the n problems together because decisions and transfers are based on the whole vector of valuations of the agents. In particular, the decision on whether or not to provide a public good depends not only on the valuations of the agents for that good but, in some cases, also on the valuations for the other goods reported by the low‐valuation agents. For the two‐agent case, we show that the mechanism is asymptotically efficient and we provide an example that compares its relative efficiency with optimal separate provision and with another asymptotically efficient mechanism in the literature.     

Informational size and incentive compatibility with aggregate uncertainty

In McLean and Postlewaite (Econometrica 56, 1992, p. 2421), we analyzed pure exchange economies with asymmetrically informed agents. We defined a notion of informational size and showed that, when the aggregate information of all agents resolves nearly all the uncertainty regarding the state of nature, the conflict between incentive compatibility and (ex post) efficiency can be made small if agents have sufficiently small informational size. This paper investigates the relationship between informational size and efficiency for the case in which nontrivial aggregate uncertainty is present, i.e., when significant uncertainty about the world persists even when the information of all agents is known.     

Truthtelling in Matching Markets

We analyze a search and matching model with non‐transferable utility and asymmetric information. Randomly paired agents go through an evaluation phase, at the end of which they discover each other's types and choose to match or not. Before deciding to enter this phase, agents can communicate through cheap talk. We provide conditions for this communication to be informative, and we examine how it affects agents' welfare. We show that communication is Pareto‐improving only when the matching is assortative in the absence of communication and left unchanged by information transmission.     

Expectations and optimal monetary policy: A stability problem revisited

A landmark result in the optimal monetary policy design literature is that fundamental-based interest rate rules invariably lead to rational expectations equilibria (REE) that are not stable under adaptive learning. In this paper, we make a novel information assumption that private agents cannot observe aggregate fundamental shocks, and use simple linear forecasting rules for learning. We find that with fundamental-based rules, there exist limited information equilibria that are stable under learning. Moreover, there are multiple equilibria. Learning can be used as a selection tool to identify a unique equilibrium.     

A Measure of the Shadow Economy in a Small Economy: Evidence from Household‐Level Expenditure Patterns

In this paper we measure the size of the shadow economy in North Cyprus by using micro‐econometric approaches and then calculate its implications on national accounts and fiscal balances. There is a relatively new strand of literature that focuses on comparing income–expenditure patterns of households to calculate the degree of underreporting of income levels by self‐employed and privately employed individuals, as compared with public servants. We use the 2008 Household Budget Survey of North Cyprus and analyze the differences in food consumption patterns among three kinds of employees: self‐employed, privately employed, and public. We found that self‐employed and privately employed individuals underreport their income levels by 20 percent and 13 percent, respectively, compared with publicly employed individuals. This has important implications for the aggregate economy in North Cyprus, where we estimate that the shadow economy created by underreporting is as much as 8.6 percent of GNP and 11.1 percent of total tax revenue.     

Mergers in the Electric Utility Industry in a Deregulatory Environment

We document that the merger announcement returns are positive and significant for targets of acquiring electric utility industry firms, but are not as algebraically large as target returns documented in non-regulated industry merger announcements. Additionally, electric utility acquirer firms earn significant negative announcement returns when acquiring an electric utility. We find announcement returns for acquirers vary significantly based upon the timing of the merger announcement, with mergers announced after the Energy Policy Act of 1992 generating negative returns for acquirers. We also find a significant difference in the percentage change in aggregate entity value around the announcement date for diversifying mergers as compared to non-diversifying mergers, with diversifying merger announcements resulting in a decrease in aggregate entity value.     

The relevance of private information in mechanism design

Recent results in mechanism design show that as long as agents have correlated private information and are sufficiently risk neutral, it is possible to design mechanisms that leave agents with arbitrarily small information rents. We show that these full-rent-extraction results hinge on the implicit assumption that the agents’ beliefs uniquely determine their preferences. We present an example of the voluntary provision of a public good in which this assumption is relaxed, and consequently, even in highly correlated environments, if agents’ beliefs do not uniquely determine their preferences, then the extraction of the agents’ entire information rents is impossible.     

On the duality between prior beliefs and trading demands

In an abstract model with asymmetric information, we show that there is a duality relationship between the prior beliefs and trading demands of bets for any given individual. Then we aggregate all the agents to obtain a second duality relationship between common prior beliefs and trading possibilities. We easily derive from these relationships the no trade theorem and its converse. General efficiency results can be obtained. Moreover, our framework is sufficiently general to cover special cases proved previously (for example, Econometrica 62 (1994) 1327; Discussion Paper 83, Center for Rationality and Interactive Decision Theory, The Hebrew University of Jerusalem, 1995; J. Econom. Theory 91 (2000) 127; Games Econom. Behav. 24 (1998) 172. Yet, our arguments are both simple and intuitive.     

Efficient allocations under ambiguity

Important implications of the expected utility hypothesis and risk aversion are that if agents have the same probability belief, then consumption plans in every efficient allocation of resources under uncertainty are comonotone with the aggregate endowment, and if their beliefs are concordant, then the consumption plans are measurable with respect to the aggregate endowment. We study these two properties of efficient allocations for models of preferences that exhibit ambiguity aversion using the concept of conditional beliefs, which we introduce in this paper. We provide characterizations of such conditional beliefs for the standard models of preferences used in applications.     

Information acquisition, dissemination, and transparency of monetary policy

Abstract.  This paper examines the role of transparency in a benevolent monetary authority's policies. Each firm's payoff depends on unobservable macroeconomic conditions and firms may incur a cost to acquire private information about macroeconomic conditions. The policy authority attempts to infer the underlying macroeconomic conditions from a noisy measure of aggregate actions and makes a public announcement to inform firms of this inference. High-quality announcements provide firms the incentive not to gather private information and base actions solely on information contained in policy announcements. However, this makes the observed actions of firms less informative to the policy authority.     

Aggregate information cascades

We introduce a new model of aggregate information cascades where only one of two possible actions is observable to others. Agents make a binary decision in sequence. The order is random and agents are not aware of their own position in the sequence. When called upon, they are only informed about the total number of others who have chosen the observable action before them. This informational structure arises naturally in many applications. Our most important result is that only one type of cascade arises in equilibrium, the aggregate cascade on the observable action. A cascade on the unobservable action never arises.     

Selecting equilibria in common agency games

We characterize equilibrium payoffs of a delegated common agency game in a public good context where principals use smooth contribution schedules. We prove that under complete information, payoff vectors of equilibria with truthful schedules coincide with the set of smooth equilibrium payoffs, including non-truthful schedules. We next consider whether the presence of arbitrarily small amounts of asymmetric information is enough to refine this payoff set. Providing that the extensions of the equilibrium schedules beyond the equilibrium point are flatter than truthful schedules, the set of equilibrium payoffs is strictly smaller than the set of smooth (equivalently, truthful) equilibrium payoffs. Interestingly, some forms of asymmetric information do not sufficiently constrain the slopes of the extensions and fail to refine the payoff set. In the case of a uniform distribution of types and arbitrary out-of-equilibrium contributions, the refinement has no bite. If, however, one restricts out-of-equilibrium behavior in a natural way, the refinement is effective. Alternatively, we may consider an exponential distribution with unbounded support (and hence no out-of-equilibrium choices) and we find that the refinement selects a unique equilibrium payoff vector equal to Lindahl prices.As a separate contribution, equilibria with forcing contracts are also considered both under complete and asymmetric information.