credible spatial preemption it is often argued that incumbent firms may deter entry by preemptive investment in new goods we show that these conclusions are reversed when multiproduct incumbentfirms may exit in response to entry once entrants are in an industry an incumbent will often want to withdraw some goods to prevent competition with the entrant from reducing profits on other goods such a reaction makes entry more attractive to a potential entrant the equilibrium industry structure is less likely to be monopolistic as the goods are better substitutes as exit costs are low and as the competition between producers of the same good is more intense

location choice product proliferation and entry deterrence within a slightly modified version of hotelling s model we reconsider the claim that the threat of entry induces existing firms to produce a larger number of products than they would otherwise we show that entry deterrence although optimal need not be achieved through product proliferation in some cases the incumbent monopolist resorts to an entry deterring strategy based on location choice rather than product proliferation we also show that in some cases the number of products chosen by the incumbent facing the threat of entry is strictly greater than the minimum number required to deter entry

oligopoly limit pricing we expand milgrom and roberts 1982 limit pricing model to allow for multiple incumbents each incumbent is informed as to the level of an industry cost parameter and selects a preentry price while a single entrant observes each incumbent s preentry price we find that incumbents are unable to coordinate deception which results in a separating equilibrium in which preentry prices are not distorted further introducing the refinement of unprejudiced beliefs we show that the no distortion equilibrium is the only refined separating equilibrium plausible pooling equilibria fail to exist or involve downward distortions in preentry prices

fairness and efficiency in multiportfolio optimization we deal with the problem faced by a portfolio manager in charge of multiple accounts we argue that because of market impact costs this setting differs in several subtle ways from the classical single account case with the key distinction being that the performance of each individual account typically depends on the trading strategies of other accounts as well we propose a novel tractable approach for jointly optimizing the trading activities of all accounts and also splitting the associated market impact costs between the accounts our approach allows the manager to balance the conflicting objectives of maximizing the aggregate gains from joint optimization and distributing them across the accounts in an equitable way we perform numerical studies that suggest that our approach outperforms existing methods employed in the industry or discussed in the literature

entry deterrence and the free rider problem the public good aspect of entry prevention is examined in an industry characterized by an established oligopoly facing a potential entrant although incumbent firms act noncooperatively underinvestment in entry deterrence does not occur and in fact incumbents may find themselves in a pareto dominated arrangement in terms of profits by preventing entry

solving the incomplete markets model with aggregate uncertainty using the krusell smith algorithm and non stochastic simulations abstract this article describes the approach to computing the version of the stochastic growth model with idiosyncratic and aggregate risk that relies on collapsing the aggregate state space down to a small number of moments used to forecast future prices one innovation relative to most of the literature is the use of a non stochastic simulation routine

capital as a commitment strategic investment to deter mobility abstract this paper analyzes how an early entrant in a market can exploit its head start by strategic investment the analysis is based on spence s paper investment strategy and growth in a new market bell j econ 10 1979 1 19 we frist study the investment game in the no discounting case which embodies the key features of mobility deterrence we establish the existence of a set of perfect equilibria and suggest that one particular equilibrium is most reasonable this equilibrium also valid with discounting involves the follower firm being forever deterred from investing to its steady state reaction curve in contrast to spence s proposed solution

almost efficient information transmission in elections abstract we study a model in which two parties compete by announcing their policies after receiving conditionally independent private signals about the true state of the world parties are both office and policy motivated our model can explain radically different policy positions even when parties receive identical signals and have unbiased preferences this holds in an asymmetric equilibrium in which both parties reveal their private information to the voters and the implemented policy is almost first best for all possible realizations of parties signals in this equilibrium one party adopts extreme and the other one moderate policy positions

monetary policy delegation and polarisation there is by now a comprehensive literature beginning with rogoff 1985 arguing that a government should delegate monetary policy to a central banker who is independent and more conservative than the government itself this will reduce the inflationary bias typically at the cost of stabilisation for a democratic society this result would suggest that the median voter should prefer that monetary policy is delegated to an independent central banker who is more conservative than herself typically the central banker is chosen by the government and the government is chosen by the electorate thus there is some albeit perhaps a weak link between the preferences of the electorate and the central banker although the central banker presumably should be chosen for a long period of time waller and walsh 1996 he has to be chosen at some point in time this paper contains a political economy model where the central issue in politics is the choice of central banker and

a theory of market structure with sequential entry this article sets out a theory of market structure with sequential entry we characterize the perfect nash equilibrium to the entry game in several propositions first equilibria never involve excess capacity second a sufficient statistic for the entry of any firm is that its profits are positive when computed myopically i e with no further entry third the equilibrium number of firms is the smallest number that can deter entry fourth aggregate output in equilibrium is no smaller than the limit output we calculate some explicit solutions to the model and examine comparative static properties

noncooperative entry deterrence uncertainty and the free rider problem previous authors who have considered the issue of noncooperative entry deterrence have not found the free rider problem to be a significant factor these authors however have only considered models in which the exact investment needed to deter entry is known with certainty in this paper i add uncertainty to the models investigated by these previous authors and demonstrate that the free rider problem can be significant but is not so in all cases that is for certain types of entry deterring investments the introduction of uncertainty causes the oligopoly to underinvest in entry deterrence however for other types no underinvestment result arises

sequential entry industry structure and welfare in this paper we reexamine the relationship between potential competition industry structure and welfare in a market subject to a sequential entry threat where firms can make quantity commitments and have access to a constant returns technology it is shown that provided entry is not blockaded the incumbent s will either prevent entry or allow all the potential entrants in furthermore actual entry may decrease but social welfare never goes down with more potential entrants nevertheless with a finite number of potential entrants policies which lower the cost of entry need not be beneficial in welfare terms

elections with privately informed parties and voters this paper studies a situation in which parties are betterinformed than voters about the optimal policies for voters weshow that voters are able to infer the parties information byobserving their electoral positions even if parties have policypreferences which differ substantially from the median voter s unlike previous work that reach opposite conclusions we assumethat voters have some private information of their own if theinformation available to voters is biased parties attempts toinfluence voters beliefs will result in less than fullconvergence even if parties know with certainty the optimalpolicy for the median voter

on the efficiency fairness trade off this paper deals with a basic issue how does one approach the problem of designing the right objective for a given resource allocation problem the notion of what is right can be fairly nebulous we consider two issues that we see as key efficiency and fairness we approach the problem of designing objectives that account for the natural tension between efficiency and fairness in the context of a framework that captures a number of resource allocation problems of interest to managers more precisely we consider a rich family of objectives that have been well studied in the literature for their fairness properties we deal with the problem of selecting the appropriate objective from this family we characterize the trade off achieved between efficiency and fairness as one selects different objectives and develop several concrete managerial prescriptions for the selection problem based on this trade off finally we demonstrate the value of our framework in a case study that considers air traffic management this paper was accepted by yossi aviv operations management

optimal portfolio liquidation with distress risk we analyze the problem of an investor who needs to unwind a portfolio in the face of recurring and uncertain liquidity needs with a model that accounts for both permanent and temporary price impact of trading we first show that a risk neutral investor who myopically deleverages his position to meet an immediate need for cash always prefers to sell more liquid assets if the investor faces the possibility of a downstream shock however the solution differs in several important ways if the ensuing shock is sufficiently large the nonmyopic investor unwinds positions more than immediately necessary and all else being equal prefers to retain more of the assets with low temporary price impact in order to hedge against possible distress more generally optimal liquidation involves selling strictly more of the assets with a lower ratio of permanent to temporary impact even if these assets are relatively illiquid the results suggest that properly accounting for the possibility of future shocks should play a role in managing large portfolios

dynamic portfolio optimization with transaction costs heuristics and dual bounds we consider the problem of dynamic portfolio optimization in a discrete time finite horizon setting our general model considers risk aversion portfolio constraints e g no short positions return predictability and transaction costs this problem is naturally formulated as a stochastic dynamic program unfortunately with nonzero transaction costs the dimension of the state space is at least as large as the number of assets and the problem is very difficult to solve with more than one or two assets in this paper we consider several easy to compute heuristic trading strategies that are based on optimizing simpler models we complement these heuristics with upper bounds on the performance with an optimal trading strategy these bounds are based on the dual approach developed in brown et al brown d b j e smith p sun 2009 information relaxations and duality in stochastic dynamic programs oper res 58 4 785 801 in this context these bounds are given by considering an investor who has access to perfect information about future returns but is penalized for using this advance information these heuristic strategies and bounds can be evaluated using monte carlo simulation we evaluate these heuristics and bounds in numerical experiments with a risk free asset and 3 or 10 risky assets in many cases the performance of the heuristic strategy is very close to the upper bound indicating that the heuristic strategies are very nearly optimal this paper was accepted by dimitris bertsimas optimization

strategic deterrence of sequential entry into an industry industrial entry deterrence is typically studied in a setting where an established firm or firms confront and attempt to deter a single potential competitor during the evolution of most industries however a sequence of firms enters or attempts to enter at distinct points in time consideration of issues arising from sequential entry fundamentally alters the qualitative nature of the deterrence decision undertaken by incumbent firms within a sequential setting counterintuitive behavior may be observed specifically numerous government policies designed to decrease industrial concentration penalties for anticompetitive practices subsidization of entry consent decrees restructuring industries may have the opposite effect

episodic liquidity crises cooperative and predatory trading we describe how episodic illiquidity arises from a breakdown in cooperation between market participants we first solve a one period trading game in continuous time using an asset pricing equation that accounts for the price impact of trading then in a multi period framework we describe an equilibrium in which traders cooperate most of the time through repeated interaction providing apparent liquidity to one another cooperation breaks down when the stakes are high leading to predatory trading and episodic illiquidity equilibrium strategies that involve cooperation across markets lead to less frequent episodic illiquidity but cause contagion when cooperation breaks down why is illiquidity rare and episodic pastor stambaugh 2003 detect only 14 aggregate low liquidity months over the time period 1962 to 1999 despite being of significant magnitude most of the episodes were short lived and were followed by long periods of liquidity 1 the origin of this empirical observation still remains a puzzle in this paper we attempt to shed light on this puzzle by developing a theoretical model in which a breakdown in cooperation between traders in the market manifests itself in predatory trading this mechanism leads to sudden and short lived illiquidity we develop a dynamic model of trading based on liquidity needs during each period a liquidity event may occur in which a trader is required to liquidate a large block of an asset in a relatively short time period this need for liquidity is observed by a tight oligopoly whose members may choose to predate or cooperate predation involves racing and fading the distressed trader to the market

securitization and lending competition we study the eects of securitization on interbank lending competition when banks see private signals of local applicants repayment chances if banks cannot securitize the outcome is e cient they lend to their most creditworthy local applicants with securitization banks lend also to remote applicants with strong observables in order to lessen the lemons problem they face in selling their securities this reliance on observables is ine cient raises the mean default risk and may lead to a deceptive rise in credit scores

industry structure with sequential technology choice abstract noncooperative entry deterrence arises in a market where firms enter sequentially and irreversibly choose a technology in the case of delegated entry deterrence the earliest firms enter with a normal technology and pass on entry deterrence responsibilities to subsequent entrants in the case of partial entry deterrence the earlliest firms choose an inferior technology that allows some but not full entry of later firms with a normal technology in both cases entry is deterred in that the equilibrium number of firms is smaller than would prevail if all firms were to choose a normal technology

the price of fairness in this paper we study resource allocation problems that involve multiple self interested parties or players and a central decision maker we introduce and study the price of fairness which is the relative system efficiency loss under a fair allocation assuming that a fully efficient allocation is one that maximizes the sum of player utilities we focus on two well accepted axiomatically justified notions of fairness viz proportional fairness and max min fairness for these notions we provide a tight characterization of the price of fairness for a broad family of problems

advertising and limit pricing we enrich milgrom and roberts 1982 limit pricing model to allow an incumbent to signal his costs with both price and advertisements our fundamental result is that a cost reducing distortion occurs in that the incumbent behaves as if there were complete information but his costs were lower than they are preentry price is therefore distorted downward and demand enhancing advertising is distorted upward as a consequence of signalling if advertising is a purely dissipative signal it is not used nor therefore distorted recent refinements of the sequential equilibrium concept are featured