the inflation tax in a real business cycle model money is incorporated into a real business cycle model using a cash in advance constraint the model economy is used to analyze whether the business cycle is different in high inflation and low inflation economies and to analyze the impact of variability in the growth rate of money in addition the welfare cost of the inflation tax is measured and the steady state properties of high and low inflation economies are compared

information constrained optima with retrading an externality and its market based solution this paper studies the efficiency of competitive equilibria in environments with a moral hazard problem and unobserved states both with retrading in ex post spot markets the interaction between private information problems and the possibility of retrade creates an externality unless preferences have special restrictive properties the externality is internalized by allowing agents to contract ex ante on market fundamentals determining the spot price or interest rate over and above contracting on actions and outputs then competitive equilibria are equivalent with the appropriate notion of constrained pareto optimality examples show that it is possible to have multiple market fundamentals or price islands created endogenously in equilibrium

asset prices in a huggett economy this paper explores asset pricing in economies where there is no direct insurance against idiosyncratic risks but other assets can be used for self insurance subject to exogenously imposed borrowing limits we analyze an endowment economy based on huggett 1993 11 both with and without aggregate risk our main innovation is that we obtain full analytical tractability by studying the case with maximally tight borrowing constraints we illustrate by looking at riskless bonds equity and the term structure of interest rates and we show that the model can reproduce many features of observed asset prices when idiosyncratic risks are quantitatively reasonable

platform competition in two sided markets many if not most markets with network externalities are two sided to succeed platforms in industries such as software portals and media payment systems and the internet must get both sides of the market on board accordingly platforms devote much attention to their business model that is to how they court each side while making money overall this paper builds a model of platform competition with two sided markets it unveils the determinants of price allocation and end user surplus for different governance structures profit maximizing platforms and not for profit joint undertakings and compares the outcomes with those under an integrated monopolist and a ramsey planner jel l5 l82 l86 l96

pareto improving social security reform when financial markets are incomplete this paper studies an overlapping generations model with stochastic production and incomplete markets to assess whether the introduction of an unfunded social security system leads to a pareto improvement when returns to capital and wages are imperfectly correlated a system that endows retired households with claims to labor income enhances the sharing of aggregate risk between generations our quantitative analysis shows that abstracting from the capital crowding out effect the introduction of social security represents a pareto improving reform even when the economy is dynamically efficient however the severity of the crowding out effect in general equilibrium tends to overturn these gains

knightian uncertainty and moral hazard abstract this paper presents a principal agent model in which the agent has imprecise beliefs we model this situation formally by assuming the agent s preferences are incomplete as in bewley 1986 2 in this setting incentives must be robust to knightian uncertainty we study the implications of robustness for the form of the resulting optimal contracts we give conditions under which there is a unique optimal contract and show that it must have a simple flat payment plus bonus structure that is output levels are divided into two sets and the optimal contract pays the same wage for all output levels in each set we derive this result for the case in which the agent s utility function is linear and then show it also holds if this utility function has some limited curvature

self insurance vs self financing a welfare analysis of the persistence of shocks abstract we study the welfare cost of market incompleteness in a generalized bewley model where idiosyncratic risk takes the form of entrepreneurial productivity shocks market incompleteness in our framework has two dimensions first in the bewley tradition only a limited set of instruments for consumption smoothing is available second entrepreneurs capital rental is subject to collateral constraints as is well known it is harder to self insure against more persistent shocks and the welfare cost of missing consumption insurance increases with shock persistence on the other hand with collateral constraints an increase in shock persistence leads to better allocation of production factors through entrepreneurs self financing and the welfare cost of imperfect capital rental markets decreases with shock persistence the overall welfare cost of market incompleteness can be increasing decreasing or even non monotone in shock persistence depending on the relative strengths of its two components the cost of missing insurance and the cost of imperfect capital markets

human capital values and returns bounds implied by earnings and asset returns data abstract we provide theory for calculating bounds on both the value of an individual s human capital and the return on an individual s human capital given knowledge of the process governing earnings and financial asset returns we calculate bounds using u s data on male earnings and financial asset returns the large idiosyncratic component of earnings risk implies that bounds on values and returns are quite loose however when aggregate shocks are the only source of earnings risk both bounds are tight

a three state model of worker flows in general equilibrium abstract we develop a simple model featuring search frictions and a nondegenerate labor supply decision along the extensive margin the model is a standard version of the neoclassical growth model with indivisible labor and idiosyncratic productivity shocks and frictions characterized by employment loss and employment opportunity arrival shocks we argue that it is able to account for the key features of observed labor market flows for reasonable parameter values persistent idiosyncratic productivity shocks play a key role in allowing the model to match the persistence of the employment and out of the labor force states found in individual labor market histories

accounting for the u s earnings and wealth inequality we show that a theory of earnings and wealth inequality based on the optimal choices of ex ante identical households that face uninsured idiosyncratic shocks to their endowments of efficiency labor units accounts for the u s earnings and wealth inequality almost exactly

regulate one service tame the entire market credit cards in turkey abstract in credit card markets banks provide both payment and credit services two regulations were recently enacted in the turkish credit card market one on payment services in 2005 and the other on credit services in 2006 by employing the well known panzar and rosse 1982 panzar and rosse 1987 method and a unique quarterly data set for 21 turkish banks between 2002 and 2008 we investigate the extent of banks market power in the turkish credit card market before and after the regulations unlike most of the existing literature which considers competition and regulation for either credit or payment services and ignores the externalities between them we consider the entire market by taking both services into account fixed effects estimations reveal that banks enjoyed collusive oligopoly power before the regulations although the first regulation did not have much impact the second led to rises in both banks total revenues and competition in the entire market

the welfare costs of moderate inflations in the recent past the view that a little bit of inflation was good for the economy was widely held the phillips curve in its earlier incarnations implied that moderate inflation was worth tolerating because it would permit lower unemployment this justification for tolerating inflation has long since been abandoned by economists and policymakers because both theory and experience showed it to be false nevertheless one legacy of this era seems to be a fairly widespread tolerance for moderate inflation recently there has been much discussion of removing this inflationary bias by passing legislation that would require the federal reserve to target zero inflation in this paper we examine some of the consequences of achieving that goal we appraise the revenue and welfare costs of policies designed to reduce moderate inflation rates to zero much has been written about why government policies may have an inflationary bias in this paper we don t address the issue of what motivates governments to inflate implicit in our analysis however is the notion that one important motive for inflation is the revenue raising potential of the inflation tax it would be difficult to argue that the inflation tax constitutes an important revenue source for the united states one indirect and very imperfect measure of this would be contributions by the federal lleserve to the treasury in recent years those rebates have amounted to

the panzar rosse revenue test and market power in banking abstract the panzar rosse h statistic is a commonly used measure of market power in banking it is widely believed that h 0 is inconsistent with significant market power this study rigorously disproves that perception instead the possibility of h 0 under conditions of substantial market power turns out robust to the timing of banks actions relative costs choice of strategic variable degree of product differentiation strategy static or dynamic and degree of heterogeneity in banks conduct collusive versus fringe and hence may be common in practice

insurance and opportunities a welfare analysis of labor market risk abstract using a model with constant relative risk aversion preferences endogenous labor supply and partial insurance against idiosyncratic wage risk this paper provides an analytical characterization of three welfare effects a the welfare effect of a rise in wage dispersion b the welfare gain from completing markets and c the welfare effect from eliminating risk the analysis reveals an important trade off for these welfare calculations on the one hand higher wage uncertainty increases the cost associated with missing insurance markets on the other hand greater wage dispersion presents opportunities to raise aggregate productivity by concentrating market work among more productive workers welfare effects can be expressed in terms of the underlying parameters defining preferences and wage risk or alternatively in terms of changes in observable second moments of the joint distribution over individual wages consumption and hours

optimal fiscal and monetary policy in an economy without capital abstract this paper is concerned with the structure and time consistency of optimal fiscal and monetary policy in an economy without capital in a dynamic context optimal taxation means distributing tax distortions over time in a welfare maximizing way for a barter economy our main finding is that with debt commitments of sufficiently rich maturity structure an optimal policy if one exists is time consistent in a monetary economy the idea of optimal taxation must be broadened to include an inflation tax and we find that time consistency does not carry over an optimal inflation tax requires commitment by rules in a sense that has no counterpart in the dynamic theory of ordinary excise taxes the reason time consistency fails in a monetary economy is that nominal assets should from a welfare maximizing point of view always be taxed away via an immediate inflation in a kind of capital levy this emerges as a new possibility when money is introduced into an economy without capital

internal rationality imperfect market knowledge and asset prices we present a decision theoretic framework in which agents are learning about market behavior and that provides microfoundations for models of adaptive learning agents are internally rational i e maximize discounted expected utility under uncertainty given dynamically consistent subjective beliefs about the future but agents may not be externally rational i e may not know the true stochastic process for payoff relevant variables beyond their control this includes future market outcomes and fundamentals we apply this approach to a simple asset pricing model and show that the equilibrium stock price is then determined by investors expectations of the price and dividend in the next period rather than by expectations of the discounted sum of dividends as a result learning about price behavior affects market outcomes while learning about the discounted sum of dividends is irrelevant for equilibrium prices stock prices equal the discounted sum of dividends only after making very strong assumptions about agents market knowledge

social security and risk sharing abstract in this paper we identify conditions under which the introduction of a pay as you go social security system is ex ante pareto improving in a stochastic olg economy with capital accumulation and land we argue that these conditions are consistent with realistic specifications of the parameters of the economy in our model financial markets are complete and competitive equilibria interim pareto efficient therefore a welfare improvement can only be obtained if agents welfare is evaluated ex ante and arises from an improvement in intergenerational risk sharing we also examine the optimal size of a given social security system as well as its optimal reform

competition human capital and income inequality with limited commitment we develop a dynamic general equilibrium model with two sided limited commitment to study how barriers to competition such as re strictions to business start up aect the incentive to accumulate hu man capital we show that a lack of contract enforceability ampli es the eect of barriers to competition on human capital accumulation high barriers reduce the incentive to accumulate human capital by lowering the outside value of skilled workers while low barriers can result in over accumulation of human capital this over accumulation can be socially optimal if there are positive knowledge spillovers a calibration exercise shows that this mechanism can account for signif icant cross country income inequality

cooperation among competitors some economics of payment card associations we analyze platforms in two sided markets with network externalities using the specific context of a payment card association we study the cooperative determination of the interchange fee by member banks the interchange fee is the access charge paid by the merchants banks the acquirers to cardholders banks the issuers we develop a framework in which banks and merchants may have market power and consumers and merchants decide rationally on whether to buy or accept a payment card after drawing the welfare implications of a cooperative determination of the interchange fee we describe in detail the factors affecting merchant resistance compare cooperative and for profit business models and make a first cut in the analysis of system competition

the optimal quantity of money a reconciliation abstract despite the apparent disagreement of samuelson s 1958 overlapping generations model and townsend s 1980 turnpike model on the optimal quantity of money in both i those endowed at the start with goods prefer a constant money stock and ii those endowed at the start with fiat money prefer deflation

power fluctuations and political economy we study constrained pareto e cient allocations in a dynamic production economy where the group that holds political power decides the allocation of resources for high discount factors the economy converges to a rst best allocation where labor supply decisions are not distorted for low discount factors distortions do not disappear and uctuate over time most importantly the set of sustainable rst best allocations is larger when there is less persistence in the identity of the party in power because this encourages political compromise this result contradicts the common presumption that there will be fewer distortions when there is a stable ruling group

self confirming equilibrium rium path of play thus if a self confirming equilibrium occurs repeatedly no player ever observes play that contradicts his beliefs even though beliefs about play at off path information sets need not be correct we characterize the ways in which self confirming equilibria and nash equilibria can differ and provide conditions under which self con firming equilibria correspond to standard solution concepts nash equilibrium and its refinements describe a situation in which i each player s strategy is a best response to his beliefs about the play of his opponents and ii each player s beliefs about the opponents play are exactly correct we propose a new equilibrium concept self confirming equilibrium that weakens condition ii by requiring only that players beliefs are correct along the equilibrium path of play thus each player may have incorrect beliefs about how his opponents would play in contingencies that do not arise when play follows the equilibrium and moreover the beliefs of different players may be wrong in different ways the concept of self confirming equilibrium is motivated by the idea that noncooperative equilibria should be interpreted as the outcome of a learning process in which players revise their beliefs using their observations of previous play suppose that each time the game is played the players observe the actions chosen by their opponents but that players do not observe the actions their opponents would have played at the information sets that were not reached along the path of play then if a self confirming equilibrium occurs repeatedly no player ever observes play that contradicts his beliefs so the equilibrium is self confirming in the weak sense of not being inconsistent with the evidence by analogy with the literature on the bandit problem e g rothschild 1974 one might expect that a non nash self confirming equilibrium can be the outcome of plausible learning processes this point was made by fudenberg and

pareto optima and competitive equilibria with adverse selection and moral hazard this paper explores the extent to which standard general equilibrium analysis of pareto optima and of competitive equilibria can be applied to environments with moral hazard and adverse selection problems allowing for lotteries contracts with random components we first establish that an adverse selection insurance economy a moral hazard insurance economy a signaling economy and a private information labor market economy are all special cases of a simple general structure we then show that techniques for characterizing pareto optimal contracts as solutions to concave programming problems are useful and nice and appear to be broadly applicable allowing for lotteries we show how to characterize the optimal allocations for the adverse selection insurance and labor market economies we then show that standard existence and optimality theorems for competitive equilibria apply in the linear space containing lotteries if agents with characteristics which are distinct and privately observed at the time of initial trading enter the economy wide resource constraints in a homogeneous way other kinds of diversity are not critical for economies with moral hazard which satisfy the homogeneity condition competitive contract markets single out a subset of the optima and thus can be consistent with apparent unemployment and with a random allocation of labor supplied though all households are averse to risk the adverse selection insurance and signaling economies however do not satisfy the homogeneity condition and are difficult to decentralize efficiently with a price system

money and interest in a cash in advance economy the authors analyze an aggregative general equilibrium model in which the use of money is motivated by a cash in advance constraint applied to purchases of a subset of consumption goods the system is subject to both real and monetary shocks which are economy wide and observed by all they develop methods for verifying the existence of characterizing and explicitly calculating equilibria copyright 1987 by the econometric society

dynamic optimal taxation with private information we study dynamic optimal taxation in a class of economies with private information optimal allocations in these environments are complicated and history dependent yet we show that they can be implemented as competitive equilibria in market economies supplemented with simple tax systems the market structure in these economies is similar to that in bewley 1986 agents supply labour and trade risk free claims to future consumption subject to a budget constraint and a debt limit optimal taxes are conditioned only on two observable characteristics an agent s accumulated stock of claims or wealth and her current labour income we show that optimal taxes are generally non linear and non separable in these variables and relate the structure of marginal wealth and income taxation to the properties of agent preferences this paper studies optimal taxation in a class of dynamic economies with private information we consider an environment in which agents preferences are defined over consumption and labour and each agent receives a privately observed sequence of i i d preference shocks incentivecompatibility constraints stemming from private information imply that socially optimal or constrained efficient allocations in this environment are complicated and history dependent yet we show that they can be implemented as competitive equilibria in market economies supplemented with simple tax systems the market structure in these economies is identical to that in bewley 1986 huggett 1993 or aiyagari 1994 agents can trade current consumption for claims to future consumption subject to a budget constraint and a borrowing limit these claims have a non contingent pre tax return crucially taxes are conditioned upon only two observable characteristics of an agent current wealth given by the agent s accumulated stock of claims and current labour income they do not depend on any other aspect of an agent s past history most models of dynamic optimal taxation follow the ramsey approach in which the set of fiscal instruments available to the government is exogenously specified 1 linear labour and capital income taxes are typically included in this set while lump sum taxes are ruled out the exclusion of the latter is justified by appealing to incentive or administrative constraints but these are not explicitly modelled these exogenous restrictions on fiscal instruments represent frictions that the government seeks to ameliorate through its optimal choice of tax rates the approach we adopt in this paper builds on the optimal taxation literature initiated by mirrlees 1971 mirrlees assumes that agents receive privately observed shocks to their

avoiding the inflation tax i study the effects of inflation on the purchasing behavior of buyers in the lagos wright monetary economy the standard framework fails to capture the long standing intuition that when inflation increases agents try to spend their money holdings speedily i propose a simple realistic extension in which buyers can rebalance their money holdings only sporadically i e not every period i show that in such a case higher inflation can induce buyers to spend their money faster by frontloading their consumption and searching more intensively for transactions these trade distortions have traditionally been associated with the economic costs of inflation

anticipated inflation and the capital stock in a cash in advance economy abstract an economy is constructed in which the steady state capital stock is inversely related to the rate of inflation as a result that is directly opposite the usual conclusion

financial integration entrepreneurial risk and global dynamics abstract how does financial integration impact capital accumulation current account dynamics and cross country inequality we investigate this question within a two country general equilibrium incomplete markets model that focuses on the importance of idiosyncratic entrepreneurial risk a risk that introduces not only a precautionary motive for saving but also a wedge between the interest rate and the marginal product of capital our contribution is to show that this friction provides a simple explanation for the emergence of global imbalances a resolution to the empirical puzzle that capital often fails to flow from the rich or slow growing countries to the poor or fast growing ones and a set of policy lessons regarding the intertemporal costs and benefits of capital account liberalization

competitive conditions among the major british banks this paper reports an empirical assessment of competitive conditions among the major british banks during a period of major structural change specifically estimates of the rosse panzar h statistic are reported for a panel of 12 banks for the period 1980 2004 the sample banks correspond closely to the major british banking groups specified by the british banking association the robustness of the results of the rosse panzar methodology is tested by estimating the ratio of lerner indices obtained from interest rate setting equations the results confirm the consensus finding that competition in british banking is most accurately characterised by the theoretical model of monopolistic competition there is evidence that the intensity of competition in the core market for bank lending remained approximately unchanged throughout the 1980s and 1990s however competition appears to have become less intense in the non core off balance sheet business of british banks

the failure of competition in the credit card market the bank credit card market containing 4 000 firms and lacking regulatory barriers casually appears to be a hospitable environment for the model of perfect competition nevertheless this article reports that credit card interest rates have been exceptionally sticky relative to the cost of funds moreover major credit card issuers have persistently earned from three to five times the ordinary rate of return in banking during the periods 1983 88 the failure of the competitive model appears to be partly attributable to consumers making credit card choices without taking account of the very high probability that they will pay interest on their outstanding balances copyright 1991 by american economic association

the risk free rate in heterogeneous agent incomplete insurance economies abstract why has the average real risk free interest rate been less than one percent the question is motivated by the failure of a class of calibrated representative agent economies to explain the average return to equity and risk free debt i construct an economy where agents experience uninsurable idiosyncratic endowment shocks and smooth consumption by holding a risk free asset i calibrate the economy and characterize equilibria computationally with a borrowing constraint of one year s income the resulting risk free rate is more than one percent below the rate in the comparable representative agent economy

inflation and welfare in the steady state this is a paper on expected inflation and welfare in steady state equilibrium the demand for money is an inventory demand with an endogenous payment period the clower constraint is not imposed higher inflation reduces welfare by reducing consumption as people devote more of their real income to maintaining lower average money holdings high inflation does not necessarily promote an increase in the capital stock the mundell tobin effect is absent the policy conclusion is standard deflate at the rate of time preference because capital is held socially optimal consumption falls short of its golden rule level if inside money is allowed it drives out fiat money and welfare is again at a maximum

switching costs and adverse selection in the market for credit cards new evidence abstract to explain persistence of credit card interest rates at relatively high levels calem and mester aer 1995 argued that informational barriers create switching costs for high balance customers as evidence using data from the 1989 survey of consumer finances they showed that these households were more likely to be rejected when applying for new credit in this paper we revisit the question using the 1998 and 2001 scf further we use new information on card interest rates to test for pricing effects consistent with information based switching costs we find that informational barriers to competition persist although their role may have declined

beyond arbitrage good deal asset price bounds in incomplete markets one often wants to value a risky payoff by reference to prices of other assets rather than by exploiting full fledged economic models however this approach breaks down if one cannot find a perfect replicating portfolio we impose weak economic restriction to derive usefully tight bounds on asset prices in this situation the bounds assume that investors would want to buy assets with high sharpe ratios good deals as well as pure arbitrage opportunities we show how to calculate the price bounds in one period multiperiod and continuous time contexts we show that the multiperiod problem can be solved recursively as a sequence of one period problems we calculate bounds in option pricing examples including infrequent trading and an option written on a nontraded event and we use the bounds to explore the economic significance of option pricing predictions we find that much variation in s p 500 index option prices over time and across strike prices fits within the bounds

efficient allocations under ambiguity abstract 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

a note on the optimum quantity of money abstract it is shown that a rise in perfectly anticipated inflation enhances welfare across steady states however this result does not invalidate optimum quantity of money rather it is the problem of inappropriately using steady states to make welfare comparisons thus non steady state analysis is necessary to evaluate the full effect of inflation

general equilibrium wariness and efficient bubbles abstract wary consumers overlook gains but not losses in remote sets of dates or states as preferences are upper but not lower mackey semi continuous bewley s 1972 4 result on existence of equilibrium whose prices are not necessarily countably additive holds wariness is related to lack of myopia and to ambiguity aversion and therefore to bewley s 1986 6 work on knightian uncertainty wary infinite lived agents have weaker transversality conditions allowing them to be creditors at infinity and for bubbles to occur in positive net supply assets completing the markets there are efficient allocations that can only be implemented with asset bubbles

crowding out and crowding in when does redistribution improve risk sharing in limited commitment economies abstract when the risk of default constrains financial contracts public insurance policies can significantly affect private risk sharing this is because by changing income expectations and volatility redistribution changes the attractiveness of default and thus endogenous borrowing constraints extending results by krueger and perri 2011 8 this paper analyses the conditions under which redistribution can improve private insurance by making default less attractive to the income rich whose income it reduces i first explain why public redistribution typically crowds out private insurance in the two income economy and identify the role of income persistence and saving after default second i show how in endowment economies with three income states or more and in economies with capital redistributive taxes can improve or crowd in private consumption insurance finally in a quantitative exercise using a realistic income process calibrated to us micro data moderate redistribution crowds in private insurance with production but not in an endowment economy