dynamic value at risk under optimal and suboptimal portfolio policies abstract at present all value at risk var implementations i e all risk measures of the maximum loss at a given level of confidence type are based on the assumption that the portfolio mix will not change before the var horizon this hypothesis may be unrealistic especially when the var horizon is established by the regulators bis at the opposite we measure var dynamically i e taking into consideration portfolio mix adjustments over time adjustments do not occur continuously since they are costly we allow both optimal rebalancing policies which entail changing the portfolio mix whenever it is too far from the optimal one and suboptimal policies which mean adjusting at pre fixed dates we show that in both cases usual var measures underestimate portfolio losses even if the underlying returns are normal we study the dependence of the misestimate on the var horizon the initial portfolio mix and the risk aversion of the portfolio manager which in turn determines the frequency of interventions the bias can be more relevant over one day than over longer horizons and even if the initial portfolio is nearly optimal we also perform backtesting and estimate a coherent risk measure namely conditional var which confirms the inappropriateness of the usual static var

proper risk aversion on introduit et on etudie une condition comportementale significative sur les fonctions d utilite pour les richesses qui signifie qu une loterie indesirable ne peut jamais etre rendue desirable par la presence d une loterie indesirable independante

wealth accumulation over the life cycle and precautionary savings this article constructs and simulates a life cycle model of wealth accumulation and estimates the parameters of the utility function the rate of time preference and the coefficient of risk aversion by matching the simulated median wealth profiles with those observed in the panel study of income dynamics and in the survey of consumer finances the estimates imply a low degree of patience and a high degree of risk aversion the results are used to study the importance of precautionary savings in explaining wealth accumulation they imply that wealth accumulation is driven mostly by precautionary motives at the beginning of the life cycle whereas savings for retirement purposes become significant only closer to retirement

speculative attacks a laboratory study in continuous time abstract we examine speculative attacks in a controlled laboratory environment featuring continuous time size asymmetries and varying amounts of public information attacks succeeded in 233 of 344 possible cases when speculators have symmetric size and access to information a weaker fundamentals increase the likelihood of successful speculative attacks and hasten their onset and b contrary to some theory success is enhanced by public access to information about either the net speculative position or the fundamentals the presence of a larger speculator further enhances success and experience with large speculators increases small speculators response to the public information however giving the large speculator increased size or better information does not significantly strengthen his impact

portfolio choice and liquidity constraints we study the infinite horizon model of household portfolio choice under liquidity constraints and revisit the portfolio specialization puzzle we show why the puzzle is robust to several model variations and argue that positive correlation between earnings shocks and stock returns is unlikely to provide an empirically plausible resolution we find that relatively small fixed costs for stock market entry are sufficient to deter stockholding because for a plausible range of parameter values households can achieve desired consumption smoothing with small or zero holdings of stocks such costs could arise from informational considerations sign up fees and investor inertia

devaluation without common knowledge in an economy with a fixed exchange rate regime that suffers a random adverse shock we study the strategies of imperfectly and sequentially informed speculators that may trigger an endogenous devaluation before it occurs exogenously the game played by the speculators has a unique symmetric nash equilibrium which is a strongly rational expectation equilibrium in the set of all strategies with delay uncertainty about the extent to which the central bank is ready to defend the peg extends the ex ante mean delay between the exogenous shock and the devaluation we determine endogenously the rate of devaluation

optimal inattention to the stock market with information costs and transactions costs recurrent intervals of inattention to the stock market are optimal if consumers incur a utility cost to observe asset values when consumers observe the value of their wealth they decide whether to transfer funds between a transactions account from which consumption must be financed and an investment portfolio of equity and riskless bonds transfers of funds are subject to a transactions cost that reduces wealth and consists of two components one is proportional to the amount of assets transferred and the other is a fixed resource cost because it is costly to transfer funds the consumer may choose not to transfer any funds on a particular observation date in general the optimal adjustment rule including the size and direction of transfers and the time of the next observation is state dependent surprisingly unless the fixed resource cost of transferring funds is large the consumer s optimal behavior eventually evolves to a situation with a purely time dependent rule with a constant interval of time between observations this interval of time can be substantial even for tiny observation costs when this situation is attained the standard consumption euler equation holds between observation dates if the consumer is sufficiently risk averse

models of currency crises with self fulfilling features the discomfort a government suffers from speculation against its currency determines the strategic incentives of speculators and the scope for multiple currency market equilibria after describing an illustrative model in which high unemployment may cause an exchange rate crisis with self fulfilling features the paper reviews some other self reinforcing mechanisms recent econometric evidence seems consistent with the practical importance of these mechanisms

discrete actions in information constrained decision problems individuals are constantly processing external information and translating it into actions this draws on limited resources of attention and requires economizing on attention devoted to signals related to economic behaviour a natural measure of such costs is based on shannon s channel capacity modelling economic agents as constrained by shannon capacity as they process freely available information turns out to imply that discretely distributed actions and thus actions that persist across repetitions of the same decision problem are very likely to emerge in settings that without information costs would imply continuously distributed behaviour we show how these results apply to the behaviour of an investor choosing portfolio allocations as well as to some mathematically simpler tracking problems that illustrate the mechanism trying to use costs of adjustment to explain stickiness of actions when interpreting the behaviour in our economic examples would lead to mistaken conclusions

the portfolio of euro area fund investors and ecb monetary policy announcements abstract this paper studies the impact of major ecb monetary policy announcements on the portfolio allocation of euro area fund investors using daily data between 2012 and mid 2016 a period that includes a variety of unconventional measures we distinguish between active portfolio reallocation driven by redemptions or injections of investors and passive portfolio rebalancing triggered by valuation effects related to changes in asset prices and exchange rates we find that for this class of fund investors policy announcements work mainly through valuation effects the signalling channel rather than via active reallocation the portfolio balance channel notably since the autumn of 2014 monetary policy shocks triggered large asset price and exchange rate effects and prompted a passive shift of euro area investors into riskier assets in particular european and emerging market equity funds and out of bond funds

financial innovation and the transactions demand for cash we document cash management patterns for households that are at odds with the predictions of deterministic inventory models that abstract from precautionary motives we extend the baumol tobin cash inventory model to a dynamic environment that allows for the possibility of withdrawing cash at random times at a low cost this modification introduces a precautionary motive for holding cash and naturally captures developments in withdrawal technology such as the increasing diffusion of bank branches and atm terminals we characterize the solution of the model which qualitatively reproduces several empirical patterns we estimate the structural parameters using micro data and show that quantitatively the model captures important economic patterns the estimates are used to quantify the expenditure and interest rate elasticity of money demand the impact of financial innovation on money demand the welfare cost of inflation and the benefit of atm ownership

currency crises sunspots and markov switching regimes abstract this paper investigates the theoretical properties of a class of escape clause models of currency crises as well as their applicability to empirical work we show that under some conditions these models give rise to an arbitrarily large number of equilibria as well as cyclic or chaotic dynamics for the devaluation expectations we then propose an econometric technique based on the markov switching regimes framework by which these models can be brought to the data we illustrate this empirical approach by studying the experience of the french franc between 1987 and 1993 and find that the model performs significantly better when it allows the devaluation expectations to be influenced by sunspots

optimal portfolio choice for long horizon investors with nontradable labor income this paper examines how risky labor income and retirement affect optimal portfolio choice with idiosyncratic labor income risk the optimal allocation to stocks is unambiguously larger for employed investors than for retired investors consistent with the typical recommendations of investment advisors increasing idiosyncratic labor income risk raises investors willingness to save and reduces their stock portfolio allocation towards the level of retired investors positive correlation between labor income and stock returns has a further negative effect and can actually reduce stockholdings below the level of retired investors financial advisors typically recommend that their customers invest more in stocks than in safe assets when they are working and to shift their investments towards safe assets when they retire jagannathan and kocherlakota 1996 malkiel 1996 by contrast the standard academic models of portfolio choice merton 1969 1971 samuelson 1969 show that retirement is irrelevant for portfolio decisions if investment opportunities are constant and human capital is tradable in this case the fraction of wealth optimally invested in risky assets should be constant over the lifetime of an individual recent research building on the pioneering work by merton 1971 shows that time varying investment opportunities result in portfolio rules with an intertemporal hedging component whose magnitude depends on the investment horizon of the investor kim and omberg 1996 balduzzi and lynch 1997 brennan schwartz and lagnado 1997 brandt 1999 campbell and viceira 1999 2001 barberis 2000 with time variation in investment opportunities retirement and death play an instrumental role as events that exogenously fix the individual s investment horizon more importantly retirement also marks the time at which individuals stop working and thereafter must live off their lifetime savings and possibly transfers from this perspective retirement matters for portfolio choice

unique equilibrium in a model of self fulfilling currency attacks even though self fulfilling currency attacks lead to multiple equilibria when fundamentals are common knowledge we demonstrate the uniqueness of equilibrium when speculators face a small amount of noise in their signals about the fundamentals this unique equilibrium depends not only on the fundamentals but also on financial variables such as the quantity of hot money in circulation and the costs of speculative trading in contrast to multiple equilibrium models our model allows analysis of policy proposals directed at curtailing currency attacks

how uncertain is household income in china abstract this paper studies the stochastic processes of household income in china using longitudinal data from chns 1989 2009 we consider both labor income and total household income we find that i compared with the us households in psid income of the chinese households is much more uncertain ii compared with the 1990s degree of income uncertainty in the 2000s is substantially higher in china

the demand for money financial innovation and the welfare cost of inflation an analysis with household data we use microeconomic data on households to estimate the parameters of the demand for currency derived from a generalized baumol tobin model our data set contains information on average currency deposits and other interest bearing assets the number of trips to the bank the size of withdrawals and ownership and use of atm cards we model the demand for currency accounting for adoption of new transaction technologies and the decision to hold interest bearing assets the interest rate and expenditure flow elasticities of the demand for currency are close to the theoretical values implied by standard inventory models however we find significant differences between individuals with an atm card and those without the estimates of the demand for currency allow us to calculate a measure of the welfare cost of inflation analogous to bailey s triangle but based on a rigorous microeconometric framework the welfare cost of inflation varies considerably within the population but never turns out to be very lar

are currency crises self fulfilling abstract this paper studies the respective roles of the fundamentals and self fulfilling speculation in currency crises we first present a model of a fixed exchange rate system in which self fulfilling speculation can arise following a bifurcation in the fundamentals we then estimate the model in the case of the 1992 3 crisis of the french franc and find some evidence that self fulfilling speculation was at work

discrete devaluations and multiple equilibria in a first generation model of currency crises the flrst generation models of currency crises have often been criticized because they predict that in the absence of very large triggering shocks currency attacks should be predictable and lead to small devaluations this paper shows that these features of flrst generation models are not robust to the inclusion of private information in particular this paper analyzes a generalization of the krugman flood garber kfg model which relaxes the assumption that all consumers are perfectly informed about the level of fundamentals in this environment the kfg equilibrium of zero devaluation is only one of many possible equilibria in all the other equilibria the lack of perfect information delays the attack on the currency past the point at which the shadow exchange rate equals the peg giving rise to unpredictable and discrete devaluations

the demand of liquid assets with uncertain lumpy expenditures abstract we consider an inventory model for a liquid asset where the per period net expenditures have two components one that is frequent and small and another that is infrequent and large we give a theoretical characterization of the optimal management of liquid asset as well as of the implied observable statistics we use our characterization to interpret some aspects of households currency management in austria as well as the management of demand deposits by a large sample of italian investors

optimal inattention to the stock market inattentive agents update their information sporadically and thus respond belatedly to news we generate optimally inattentive behavior by assuming that to observe the value of his investment portfolio the consumer must pay a cost that is proportional to the portfolio s contempo raneous value it is optimal for the consumer to check his investment portfolio at equally spaced points in time consuming from a riskless trans actions account in the interim the riskless transactions account that finances consump tion guarantees that funds are never unwittingly exhausted we show that the optimal interval of time between consecutive observations of the value of the portfolio is the unique positive solution to a nonlinear equation quantitatively even a small observation cost one basis point of wealth implies a substantial eight month decision interval under conventional parameter values

collapsing exchange rate regimes another linear example abstract in the literature on speculative attacks on a fixed exchange rate it is usually assumed that the monetary authority responsible for fixing the rate reacts passively to the monetary disruption caused by the attack this assumption is grossly at odds with actual experience where the monetary base implications of the attacks are usually sterilized such sterilization means that the attack is no longer exclusively a monetary event and requires that the standard attack model be broadened to include the effects of sterilization on other markets these issues are motivated by reference to the december 1994 collapse of the mexican peso

saving and liquidity constraints this paper is concerned with the theory of saving when consumers are not permitted to borrow and with the ability of such a theory to account for some of the stylized facts of saving behavior the models presented in the paper seem to account for important aspects of reality that are not explained by traditional life cycle models copyright 1991 by the econometric society

household search choice theory and evidence since the work by stigler 1961 on the economics of information in the early 1960s economists have paid closer attention to the role of search for information however search methods are not considered in the theory of portfolio choice we present a model of investor search behaviour in order to provide a framework by which to evaluate our empirical evidence on the role of search in portfolio selection and performance we study two types of search methods informal and professional we show that the income wealth and risk preference of households influence their search choice

rationalizable strategic behavior the notion of equilibrium proposed by nash 19 has come to play a dominant role in economic applications of noncooperative games while analyses of nash equilibria have unquestionably contributed to our understanding of economic behavior it would be unreasonably optimistic to maintain that nash solved the problem of noncooperative strategic choice there is a small literature beginning with ellsberg 6 and a much larger oral tradition which argues that nash behavior is neither a necessary consequence of rationality nor a reasonable empirical proposition in this paper i take the view that although there may be various reasons why an agent might select a nash strategy the notion of an equilibrium has little intrinsic appeal within a strategic context when an agent reaches a decision in ignorance of the strategies adopted by other players rationality consists of making a choice which is justifiable by an internally consistent system of beliefs rather than one which is optimal post hoc this point of view is not original indeed most serious justifications of the nash hypothesis embrace such an approach arguing that agents will expect the game to yield a nash outcome and consequently will choose their equilibrium strategies nevertheless when we think in terms of maximizing utility subject to expectations rather than realizations it becomes clear that the nash hypothesis far from being a consequence of rationality arises from certain restrictions on agents expectations which may or may not be plausible depending upon the game being played we are then quite naturally led to ask are there any restrictions of individuals expectations and hence choices which are required by rationality alone rather than by subjective plausibility this paper is concerned with defining justifying characterizing and refining a criterion for rational strategic choice which i label rationalizability

monetary shocks in models with observation and menu costs we study economies where price stickiness arises due to the simultaneous presence of both menu and information costs we identify the relative importance of these costs using firm s survey data and analyze the response of prices and output following a permanent unexpected monetary shock for a given frequency of price adjustment we find that the information friction significantly amplifies the real effect of the shock when the shock is small or when it is not known by firms instead when the shock is large and known to firms the flexibility of prices increases and the real effects gradually vanish

equilibrium pricing and trading volume under preference uncertainty information collection processing and dissemination financial institutions is challenging this can delay the observation by traders of the exact capital charges and constraints of their institution during this delay traders face preference uncertainty in this context we study optimal trading strategies and equilibrium prices in a continuous centralized market we focus on liquidity shocks during which preference uncertainty is likely to matter most preference uncertainty generates allocative ineficiency but need not reduce prices traders progressively learning about the preferences of their institution conduct round trip trades which generate excess volume relative to the frictionless market in a cross section of liquidity shocks the initial price drop is positively correlated with total trading volume across traders the number of round trips is negatively correlated with trading profits and average inventory

transactions costs and portfolio choice in a discrete continuous time setting abstract this paper makes the following observation concerning a new formulation of the consumption and portfolio choice model of merton 1971 with transaction costs suppose an investor observes his or her current wealth only when making a transaction that transactions are costly and that decisions to transact can be made at any time based on all current information if at each transaction the agent is charged a fixed fraction of current portfolio value an optimal policy exists and the optimal interval of time between transactions is fixed independent of time and current wealth

a linearized value at risk model with transaction costs and short selling abstract though value at risk var has been widely applied by finance industry a possibility of multiple optimums that is caused by the nonlinearity in modeling can challenge its application to deal with this technical issue we propose a linearized var model that employs the mixed 0 1 programing in lin 2009 p4 model we further advance the previous models with considering various transaction costs and the optimization of short selling weights we compare the performance of buy and hold bh strategy the mean variance mv model the original p4 model and our linearized p4 lp4 model by rebalancing a wide scale of international and alternative investments during a period between 2001 and 2012 the results of numerical tests show the superior performance of the var models to the bh and the mv portfolios the lp4 model yields the global optimum and outperforms the corresponding p4 model in both return and risk the stability of portfolio value generated from the lp4 model supports its higher effectiveness in risk management than the p4 model

60 years of portfolio optimization practical challenges and current trends abstract the concepts of portfolio optimization and diversification have been instrumental in the development and understanding of financial markets and financial decision making in light of the 60 year anniversary of harry markowitz s paper portfolio selection we review some of the approaches developed to address the challenges encountered when using portfolio optimization in practice including the inclusion of transaction costs portfolio management constraints and the sensitivity to the estimates of expected returns and covariances in addition we selectively highlight some of the new trends and developments in the area such as diversification methods risk parity portfolios the mixing of different sources of alpha and practical multi period portfolio optimization

an exploration of the eductive justifications of the rational expectations hypothesis this paper examines justifications of the rational expectations hypothesis that rely on the analysis of the agents mental forecasting educing activity which involves forecasting the forecasts of others etc the corresponding concept of eductive learning stability based on the game theoretical concept of rationalizability is primarily used within the classical muth model conditions for coordination of beliefs are interpreted and discussed they are robust to the introduction of noise more generally eductive stability fits economic intuition on coordination stability increases when the industry product differentiation increases and when decisions are sequential and observable copyright 1992 by american economic association

on the taxation of durable goods this paper proposes a mirrleesian theory of commodity taxation in the presence of durable goods nondurable goods should be taxed uniformly provided that the preferences over nondurable consumption are weakly separable from labor effort a uniform taxation across all goods is optimal if the utility from durable consumption is linear and the preferences are additively separable between durable goods nondurable goods and labor effort if those conditions are not met wealth effects and substitution effects justify the use of differential commodity taxes to characterize the sign of the tax differential the paper exploits a substitution euler equation that links the marginal rate of substitution between durable and nondurable consumption across time finally an application of this theory suggests that housing investment should face higher tax rates than nondurable consumption

rationalizable strategic behavior and the problem of perfection this paper explores the fundamental problem of what can be inferred about the outcome of a noncooperative game from the rationality of the players and from the information they possess the answer is summarized in a solution concept called rationalizability strategy profiles that are rationalizable are not always nash equilibria conversely the information in an extensive form game often allows certain unreasonable nash equilibria to be excluded from the set of rationalizable profiles a stronger form of rationalizability is appropriate if players are known to be not merely rational but also cautious what constitutes rational behavior in a noncooperative strategic situation this paper explores the issue in the context of a wide class of finite noncooperative games in extensive form the traditional answer relies heavily upon the idea of nash equilibrium nash 17 the position developed here however is that as a criterion for judging a profile of strategies to be reasonable choices for players in a game the nash equilibrium property is neither necessary nor sufficient some nash equilibria are intuitively unreasonable and not all reasonable strategy profiles are nash equilibria the fact that a nash equilibrium can be intuitively unattractive is well known the equilibrium may be imperfect introduced into the literature by selten 20 the idea of imperfect equilibria has prompted game theorists to search for a narrower definition of equilibrium while this research some of which will be discussed here has been extremely instructive it remains inconclusive theorists often agree about what should happen in particular games but to capture this intuition in a general solution concept has proved to be very difficult if this paper is successful it should make some progress in that direction the other side of the coin has received less scrutiny can all non nash profiles really be excluded on logical grounds i believe not the standard justifications for considering only nash profiles are circular in nature or make gratuitous assumptions about players decision criteria or beliefs the following discussion of these points is extremely brief due to space constraints more detailed arguments may be found in pearce 18

a news utility theory for inattention and delegation in portfolio choice recent evidence suggests that investors are inattentive to their portfolios and hire expensive portfolio managers this paper develops a life cycle portfolio choice model in which the investor experiences loss averse utility over news and can ignore his portfolio in such a model the investor prefers to ignore and not rebalance his portfolio most of the time because he dislikes bad news more than he likes good news such that expected news causes a first order decrease in utility consequently the investor has a first order willingness to pay a portfolio manager who rebalances actively on his behalf moreover the investor can diversify over time and his consumption aligns with predictions of mental accounting i structurally estimate the preference parameters by matching stock shares and stock market non participation over the life cycle my parameter estimates are in line with the literature generate reasonable intervals of inattention and simultaneously explain consumption and wealth accumulation over the life cycle here it matters that news utility preserves first order risk aversion even in the presence of stochastic labor income which also causes stock shares to rise in wealth

income risk borrowing constraints and portfolio choice economic theory suggests that uninsurable income risk and the expectation of future borrowing constraints can reduce the share of risky assets in a household s portfolio if the utility function exhibits decreasing absolute risk aversion and decreasing prudence an individual will reduce his exposure to rate of return risks when confronted with other independent risks if there are transaction costs the expectation of future borrowing constraints should induce individuals to keep a lower proportion of their wealth in the form of illiquid and risky assets the authors find support for these propositions in a cross section of italian households copyright 1996 by american economic association

the liquid hand to mouth evidence from personal finance management software we use a very accurate panel of all individual spending income balances and credit limits from a personal finance software to document spending responses to the arrival of both regular and irregular income these payday responses are robust and homogeneous for all income and spending categories throughout the income distribution moreover we find that few people hold little or no liquidity we then analyze whether people hold liquidity cushions to cope with future liquidity constraints however we find that peoples responses are consistent with standard models without illiquid savings in which neither present nor future liquidity constraints are frequently binding received may 31 2016 editorial decision september 30 2017 by editor itay goldstein

small cues change savings choices we present evidence from randomized field experiments that 401 k savings choices are significantly affected by one to two sentence anchoring goal setting or savings threshold cues embedded in emails sent to employees about their 401 k plan even though these cues contain little to no marginal information cues that make high savings rates salient increased 401 k contribution rates by up to 2 9 of income in a pay period and cues that make low savings rates salient decreased 401 k contribution rates by up to 1 4 of income in a pay period cue effects persist between two months and a year after the email

multivariate dependence and portfolio optimization algorithms under illiquid market scenarios we propose a model for optimizing structured portfolios with liquidity adjusted value at risk lvar constraints whereby linear correlations between assets are replaced by the multivariate nonlinear dependence structure based on dynamic conditional correlation t copula modeling our portfolio optimization algorithm minimizes the lvar function under adverse market circumstances and multiple operational and financial constraints when we consider a diversified portfolio of international stock and commodity market indices under multiple realistic portfolio optimization scenarios the obtained results consistently show the superiority of our approach relative to other competing portfolio strategies including the minimum variance risk parity and equally weighted portfolio allocations

durable consumption and asset management with transaction and observation costs this paper provides a contribution to the recent growing literature on rational inattention we start by testing the implications of recent rational inattention models of asset management liquidity holdings and savings using two novel datasets some predictions of these models are at odds with the data which motivates us to introduce a new model that shifts the focus from non durable to durable consumption and features both information and adjustment costs the focus on non durable consumption which departs from the previous literature is key to improve the fit of the model the investor s behavior in our setup combines elements of what the literature refers to as state dependent and time dependent adjustments the model allows us to quantify the information and transactions costs that are consistent with observed patterns of information review and asset trades a calibration of the model shows that very small information costs are sufficient to reproduce the relatively high frequency of observation that is found in the data we test a novel prediction of the model on the relationship between assets trades and durable goods trades and find it aligned with the data

portfolio inertia and stock market fluctuations this paper uses population wide data from the panel study of income dynamics and the survey of consumer finances to resolve the conflict between overtrading and inactivity shown in administrative data on brokerage and retirement accounts respectively considerable inertia is found and linked to characteristics e g limited education or resources but less to index movements the downswing has encouraged staying out rather than getting out of the market the small minority with brokerage accounts exhibits important differences in trading patterns relative to the population and invests small fractions of wealth in brokerage accounts results strengthen the case for default options in retirement accounts and built in trading provisions in mutual funds

life cycle portfolio choice with liquid and illiquid financial assets abstract traditionally quantitative models that have studied households portfolio choices have focused exclusively on the different risk properties of alternative financial assets we introduce differences in liquidity across assets in the standard life cycle model of portfolio choice more precisely in our model stocks are subject to transaction costs as considered in recent macroliterature we show that when these costs are calibrated to match the observed infrequency of households trading the model is able to generate patterns of portfolio stock allocation over age and wealth that are constant or moderately increasing thus more in line with the existing empirical evidence

moving costs nondurable consumption and portfolio choice the substantial adjustment cost for housing affects nondurable consumption and portfolio allocations as well as the frequency of housing transactions a simple theoretical model roughly calibrated is used to assess the quantitative impact of adjustment costs on those decisions the impact on portfolios is found to be significant suggesting that housing wealth should be useful in empirical studies of portfolio choice the welfare loss from the transaction cost is also substantial the effect on nondurable consumption is small however so adjustment costs can explain only a small part of the equity premium puzzle

investment dynamics with information costs investment in physical capital at the micro level is infrequent and large or lumpy the most common explanation for this is that firms face non convex physical adjustment costs the model developed in this paper shows that information costs make investment lumpy at the micro level even in the absence of non convex adjustment costs when collecting and processing information is costly the firm optimally chooses to do it sporadically and to be inactive most of the time this behavior results in infrequent and possibly large capital adjustments the model fits plant level investment rate moments well and it also matches some higher order moments of aggregate investment rates keywords investment dynamics information costs inattentiveness lumpy investment jel classification d21 d83 d92 e22

the risk premium and long run global imbalances this study proposes that heterogeneous household portfolio choices within a country and across countries offer an explanation for global imbalances we construct a stochastic growth multi country model in which heterogeneous agents face the following restrictions on asset trade first the degree of us equity market participation is higher than that of the rest of the world second a fraction of households in each country maintains a fixed share of equity in its portfolios in our calibrated model which matches the us net foreign asset position and the equity premium the average us household loads up more aggregate risk than the average foreign household by investing in risky assets abroad and issuing risk free assets as a result the us is compensated by a high risk premium and runs trade deficits even as a debtor country the long run average trade deficit in our model accounts for 50 of the observed us trade deficit

incorporating asymmetric distributional information in robust value at risk optimization value at risk var is one of the most widely accepted risk measures in the financial and insurance industries yet efficient optimization of var remains a very difficult problem we propose a computationally tractable approximation method for minimizing the var of a portfolio based on robust optimization techniques the method results in the optimization of a modified var measure asymmetry robust var arvar that takes into consideration asymmetries in the distributions of returns and is coherent which makes it desirable from a financial theory perspective we show that arvar approximates the conditional var of the portfolio as well numerical experiments with simulated and real market data indicate that the proposed approach results in lower realized portfolio var better efficient frontier and lower maximum realized portfolio loss than alternative approaches for quantile based portfolio risk minimization

risk aversion wealth and background risk we use household survey data to construct a direct measure of absolute risk aversion based on the maximum price a consumer is willing to pay for a risky security we relate this measure to consumer s endowments and attributes and to measures of background risk and liquidity constraints we find that risk aversion is a decreasing function of the endowment thus rejecting cara preferences we estimate the elasticity of risk aversion to consumption at about 0 7 below the unitary value predicted by crra utility we also find that households attributes are of little help in predicting their degree of risk aversion which is characterized by massive unexplained heterogeneity we show that the consumer s environment affects risk aversion individuals who are more likely to face income uncertainty or to become liquidity constrained exhibit a higher degree of absolute risk aversion consistent with recent theories of attitudes toward risk in the presence of uninsurable risks jel d1 d8

heterogeneous consumers segmented asset markets and the real effects of monetary policy this paper proposes a novel mechanism by which changes in the distribution of money holdings have real effects specifically i develop a flexible price model of segmented asset markets that generates real aggregate effects of monetary policy through the dependence of optimal markups on the heterogeneity of money holdings because varieties of consumption bundles are purchased sequentially newly injected money disseminates slowly throughout the economy via second round effects the model predicts a short term inflation output trade off a liquidity effect countercyclical markups and procyclical wages after monetary shocks among other correlations of financial variables it also reproduces the empirical negative relationship between changes in the money supply and markups

houses as atms mortgage refinancing and macroeconomic uncertainty we estimate a structural model of household liquidity management in the presence of long term mortgages households face counter cyclical idiosyncratic labor income uncertainty and borrowing constraints which aect optimal choices of leverage precautionary saving in liquid assets and illiquid home equity debt repayment mortgage renancing and default taking the observed historical path of house prices aggregate

consumption smoothing and portfolio rebalancing the effects of adjustment costs abstract a household s response to income and return shocks depends on the costs of portfolio adjustment in particular the extent of portfolio rebalancing and consumption smoothing are influenced by the presence of non convex portfolio adjustment costs suppose bonds can be adjusted costlessly while adjustments to stock accounts entail adjustment costs due to these portfolio adjustment costs the household demands both stocks and bonds a household can buffer some income fluctuations without incurring adjustment costs and engage in costly portfolio rebalancing less frequently using the estimated preference parameters and portfolio adjustment costs the response to income and return shocks is nonlinear and reflects the interaction of portfolio rebalancing and consumption smoothing

a semiparametric bayesian approach to the analysis of financial time series with applications to value at risk estimation abstract garch models are commonly used for describing estimating and predicting the dynamics of financial returns here we relax the usual parametric distributional assumptions of garch models and develop a bayesian semiparametric approach based on modeling the innovations using the class of scale mixtures of gaussian distributions with a dirichlet process prior on the mixing distribution the proposed specification allows for greater flexibility in capturing the usual patterns observed in financial returns it is also shown how to undertake bayesian prediction of the value at risk var the performance of the proposed semiparametric method is illustrated using simulated and real data from the hang seng index hsi and bombay stock exchange index bse30

optimal price setting with observation and menu costs we study the price setting problem of a firm in the presence of both observation and menu costs in this problem the firm optimally decides when to collect costly information on the adequacy of its price an activity which we refer to as a price review upon each review the firm chooses whether to adjust its price subject to a menu cost and when to conduct the next price review this behavior is consistent with recent survey evidence documenting that firms revise prices infrequently and that only a few price revisions yield a price adjustment the goal of the paper is to study how the firm s choices map into several observable statistics depending on the level and relative magnitude of the observation vs the menu cost the observable statistics are the frequency of price reviews the frequency of price adjustments the size distribution of price adjustments and the shape of the hazard rate of price adjustments we provide an analytical characterization of the firm s decisions and a mapping from the structural parameters to the observable statistics we compare these statistics with the ones obtained for the models with only one type of cost the predictions of the model can with suitable data be used to quantify the importance of the menu cost vs the information cost we also consider a version of the model where several price adjustment are allowed between observations a form of price plans or indexation we find that no indexation is optimal for small inflation rates

labor supply flexibility and portfolio choice in a life cycle model abstract this paper examines the effect of the labor leisure choice on portfolio and consumption decisions over an individual s life cycle the model incorporates the fact that individuals may have considerable flexibility in varying their work effort including their choice of when to retire given this flexibility the individual simultaneously determines optimal levels of current consumption labor effort and an optimal financial investment strategy at each point in his life cycle we show that labor and investment choices are intimately related the ability to vary labor supply ex post induces the individual to assume greater risks in his investment portfolio ex ante

rational and self fulfilling balance of payments crises speculative attacks on a pegged exchange rate must sometimes occur ifasset price paths are to be free of abnormal profit opportunities suchattacks are fully rational as they reflect the market s response to aregime breakdown that is inevitable the authors shows that under someexpectations about policy balance of payments crises can also be purely self fulfilling events in such cases even a permanently viableregime may collapse and the economy will possess multiple equilibriacorresponding to different subjective assessments of the probability ofa crisis the behavior of the domestic interest rate will naturally reflect the possibility of a speculative attack copyright 1986 by american economic association

income risk and portfolio choice an empirical study this paper investigates the relationship between portfolio choice and labor income risk in the national longitudinal survey of youth 1979 cohort permanent income risk variability of shocks to income that have permanent effect significantly reduces the share of risky assets in the household s portfolio while transitory income risk variability of shocks with no lasting effect does not this result provides strong evidence that households portfolio choices respond to labor income risks in a manner consistent with economic theory theoretical work has shown that uninsurable labor income risk is likely to reduce the share of risky assets in an investor s portfolio pratt and zeckhauser 1987 kimball 1993 bertaut and haliassos 1997 koo 1998 1999 elmendorf and kimball 2000 in a dynamic context when labor in come consists of components of different persistence the magnitude of this effect should depend on the persistence associated with the risk the risk to a persistent component should have a larger effect than the risk to a transi tory component surprisingly however empirical work has not examined this interesting implication of the theory this paper uses the rich information con tained in the national longitudinal survey of youth 1979 cohort nlsy79 to examine this implication we assume that labor income has two components permanent and transitory we then measure the risks of the components for a sample of households in the survey and estimate their effects on the risky asset share previous empirical

coordination of speculation abstract we extend the models of krugman journal of money credit and banking 11 1979 311 and flood and garber journal of international economics 17 1984 1 on balance of payments crises to a multi country setting such that coordination among speculators is important for a focal point to emerge the moment of successful coordination when the currency is devalued is shown to depend on initial beliefs the degree of imperfect communication the rate of domestic credit creation and the number of countries that have overvalued currencies contagion arises naturally in our framework subsequent speculative attacks occur faster and faster and communication among speculators results in fluctuating stocks of reserves prior to the attack

collapsing exchange rate regimes some linear examples abstract we construct a pair of linear examples to study the collapse time of a fixed exchange rate regime the first example is a perfect foresight continuous time model which allows calculation of the exact collapse time and the tracking of reserves the second example is a discrete time stochastic model which yields an endogenous probability distribution over the collapse time and produces a forward discount of the exchange rate

small menu costs and large business cycles a macroeconomic model of monopoly i introduction the conflict between modern neoclassical and traditional keynesian theories of the business cycle centers upon the pricing mechanism in neoclassical models prices are fully flexible they represent the continuous optimization of economic agents and the continuous intersection of supply and demand in keynesian models prices are often assumed to be sticky they do not necessarily equilibrate all markets at all times one of the reasons for the resurgence of the equilibrium approach to macroeconomics has been the absence of a theoretical underpinning for this keynesian price stickiness this note shows that sticky prices can be both privately efficient and socially inefficient the business cycle results from the suboptimal adjustment of prices in response to a demand shock to the extent that policy can stabilize aggregate demand it can mitigate the social loss due to this suboptimal adjustment in some keynesian models prices are simply exogenously fixed 2 in others agents must set their prices in advance of the transaction date the act of altering a posted price is certainly costly these costs include such items as printing new catalogs and informing salesmen of the new price yet these menu costs are small and therefore generally perceived as providing only a weak foundation for these fixed price models however this inference is flawed small menu costs can cause large welfare losses the claim that price adjustment costs are small does not rebut the claim that they are central to understanding economic fluctuations

dynamic speculative attacks this paper presents a model of rational bayesian agents with speculative attacks in a regime of exchange rate which is pegged within a band speculators learn from the observation of the exchange rate within the band whether their mass is sufficiently large for a successful attack multiple periods are necessary for the existence of speculative attacks various defense policies are analyzed a trading policy by the central bank may defend the peg if it is unobserved and diminishes the market s information for the coordination of speculators

presidential address asset price dynamics with slow moving capital i describe asset price dynamics caused by the slow movement of investment capital to trading opportunities the pattern of price responses to supply or demand shocks typically involves a sharp reaction to the shock and a subsequent and more extended reversal the amplitude of the immediate price impact and the pattern of the subsequent recovery can reflect institutional impediments to immediate trade such as search costs for trading counterparties or time to raise capital by intermediaries i discuss special impediments to capital formation during the recent financial crisis that caused asset price distortions which subsided afterward after presenting examples of price reactions to supply shocks in normal market settings i offer a simple illustrative model of price dynamics associated with slow moving capital due to the presence of inattentive investors i address the implications for asset price dynamics of the apparent slow movement of investment capital to trading opportunities the arrival of new capital to an investment opportunity can be delayed by fractions of a second in some markets for example an electronic limit order book market for equities or by months in other markets such as that for catastrophe risk insurance accordingly prices respond to supply or demand shocks with a sharp reaction because of the relatively small subset of capital and thus risk bearing capacity that is immediately available to absorb a shock on short notice such a price impact is substantially reversed over time as additional capital becomes available the amplitude of the immediate price impact and the pattern of the subsequent recovery can reflect many sorts of attention costs to trade as well as institutional impediments to capital movement such as search costs for trading

sluggish responses of prices and inflation to monetary shocks in an inventory model of money demand we examine the responses of prices and inflation to monetary shocks in an inventory theoretic model of money demand we show that the price level responds sluggishly to an exogenous increase in the money stock because the dynamics of households money inventories leads to a partially offsetting endogenous reduction in velocity we also show that inflation responds sluggishly to an exogenous increase in the nominal interest rate because changes in monetary policy affect the real interest rate in a quantitative example we show that this nominal sluggishness is substantial and persistent if inventories in the model are calibrated to match u s households holdings of m2

worst case value at risk of nonlinear portfolios portfolio optimization problems involving value at risk var are often computationally intractable and require complete information about the return distribution of the portfolio constituents which is rarely available in practice these difficulties are compounded when the portfolio contains derivatives we develop two tractable conservative approximations for the var of a derivative portfolio by evaluating the worst case var over all return distributions of the derivative underliers with given first and second order moments the derivative returns are modelled as convex piecewise linear or by using a delta gamma approximation as possibly nonconvex quadratic functions of the returns of the derivative underliers these models lead to new worst case polyhedral var wpvar and worst case quadratic var wqvar approximations respectively wpvar serves as a var approximation for portfolios containing long positions in european options expiring at the end of the investment horizon whereas wqvar is suitable for portfolios containing long and or short positions in european and or exotic options expiring beyond the investment horizon we prove that unlike var that may discourage diversification wpvar and wqvar are in fact coherent risk measures we also reveal connections to robust portfolio optimization this paper was accepted by dimitris bertsimas optimization

precautionary portfolio behavior from a life cycle perspective abstract the literature on household asset accumulation draws a sharp distinction between short run precautionary motives to buffer consumption from annual income shocks and long run life cycle considerations under income certainty however estimates of shock persistence imply considerable career uncertainty we study long run precautionary motives for life cycle wealth accumulation and portfolios allowing for uncertain returns incomes and lifespan we separate the effects of various factors on mean and median asset holdings including education risk aversion household heterogeneity bequests impatience variance and serial correlation of income shocks numerical solutions are compared with data from the 1992 survey of consumer finances

dynamics of currency crises with asset market frictions abstract this paper presents a dynamic model of currency crises with frictions by construction a speculative attack is not an instantaneous event but takes a little time to deplete the country s reserves and in the event of an attack agents are uncertain about whether they will be able to act before the devaluation comes the currency will be overvalued ripe for attack for a long time before an attack takes place a discrete and sizable devaluation will occur small changes in fundamentals may trigger an attack the model brings insights about the dynamics of currency crises and the effects of some key policy variables

why are exchange rates so smooth a household finance explanation abstract empirical moments of asset prices and exchange rates imply that pricing kernels are almost perfectly correlated across countries otherwise observed real exchange rates would be too smooth for high sharpe ratios however the cross country correlation among macro fundamentals is weak we reconcile these facts in a two country stochastic growth model with heterogeneous households and a home bias in consumption in our model only a small fraction of households trade domestic and foreign equities we show that this mechanism can quantitatively account for the smoothness of exchange rates in the presence of volatile pricing kernels and weakly correlated macro fundamentals

portfolio rebalancing and asset pricing with heterogeneous inattention can households inattention to the stock market quantitatively account for the inertia in portfolio rebalancing i address this question by introducing an observation cost into a production economy with heterogeneous agents in this environment inattention changes endogenously over time and across agents i find that inattention explains the inertia in portfolio rebalancing and its heterogeneity across households inattention also rationalizes the limited stock market participation observed in the data and improves the asset pricing performance of the model finally i present a novel testable implication linking the effects of inattention on portfolio choices and asset prices to households funding liquidity

wealth information acquisition and portfolio choice i solve with an approximation a grossman stiglitz economy under general preferences thus allowing for wealth effects because information generates increasing returns decreasing absolute risk aversion in conjunction with the availability of costly information is sufficient to explain why wealthier households invest a larger fraction of their wealth in risky assets one no longer needs to resort to decreasing relative risk aversion an empirically questionable assumption furthermore i show how to distinguish empirically between these two explanations finally i find that the availability of costly information exacerbates wealth inequalities copyright 2004 oxford university press

implications of rational inattention abstract a constraint that actions can depend on observations only through a communication channel with finite shannon capacity is shown to be able to play a role very similar to that of a signal extraction problem or an adjustment cost in standard control problems the resulting theory looks enough like familiar dynamic rational expectations theories to suggest that it might be useful and practical while the implications for policy are different enough to be interesting

caviar conditional autoregressive value at risk by regression quantiles value at risk var has become the standard measure of market risk employed by financial institutions for both internal and regulatory purposes var is defined as the value that a portfolio will lose with a given probability over a certain time horizon usually one or ten days despite its conceptual simplicity its measurement is a very challenging statistical problem and none of the methodologies developed so far give satisfactory solutions interpreting the var as the quantile of future portfolio values conditional on current information we propose a new approach to quantile estimation which does not require any of the extreme assumptions invoked by existing methodologies such as normality or i i d returns the conditional autoregressive value at risk or caviar model moves the focus of attention from the distribution of returns directly to the behavior of the quantile we specify the evolution of the quantile over time using a special type of autoregressive process and use the regression quantile framework introduced by koenker and bassett to determine the unknown parameters since the objective function is not differentiable we use a differential evolutionary genetic algorithm for the numerical optimization utilizing the criterion that each period the probability of exceeding the var must be independent of all the past information we introduce a new test of model adequacy the dynamic quantile test applications to simulated and real data provide empirical support to this methodology and illustrate the ability of these algorithms to adapt to new risk environments

information aggregation in a noisy rational expectations economy abstract this paper analyzes a general equilibrium model of a competitive security market in which traders possess independent pieces of information about the return of a risky asset each trader conditions his estimate of the return both on his own private source of information and price which in equilibrium serves as a noisy aggregator of the total information observed by all traders a closed form characterization of the rational expectations equilibrium is presented a counter example to the existence of fully revealing equilibrium is developed