on the exclusion of assets from tests of the mean variance efficiency of the market portfolio this paper presents an analysis of the testability of the mean variance efficiency of a market index when the returns on some components of the index itself are not perfectly observable the results are basically not supportive of the notion that mean variance efficiency is testable on a subset of the assets bounding the market share of the missing asset and its expected return is not sufficient to produce a valid test when the variance of the missing asset is bounded and the amount of wealth that might be missing is small it is possible in principle to reject correctly the mean variance efficiency of a market index in his famous critique of the asset pricing theory tests roll 7 concludes that the only testable hypothesis associated with the generalized two parameter asset pricing model of black 1 is that the market portfolio is mean variance efficient it has been emphasized by ross 10 and roll 7 that the mean variance efficiency of the market portfolio is mathematically equivalent to a positive linear relation between expected returns and the betas calculated against such a portfolio roll 7 deduces that the theory capm is not testable unless the exact composition of the market portfolio is known and used in the tests this implies that the theory is not testable unless all individual assets are included in the sample errors of type one or two might occur when a market proxy is used instead of the true market portfolio even if the ex ante true expected returns and the covariance variance matrix of the returns on all the assets are used these errors are the result of the choice of the portfolio and as roll puts it even a small misspecification of the proxy s composition can lead to the wrong conclusion the market proxy might be mean variance efficient while the true market portfolio is not and vice versa in principle however there are cases in which the above two conditions are not both necessary to reject the theory one such exception presented by roll 7 is the case in which no totally positive portfolio is efficient if any totally positive market proxy is used a large sample would reject the null hypothesis unambiguously while the market portfolio identification problem constitutes a severe limitation to the testability of the theory the question of the mean variance efficiency of a particular market index with respect to a subset of assets is a typical problem of statistical inference the mean variance efficiency can be tested directly or by

equilibrium in an ambiguity averse mean variance investors market abstract in a financial market composed of n risky assets and a riskless asset where short sales are allowed and mean variance investors can be ambiguity averse i e diffident about mean return estimates where confidence is represented using ellipsoidal uncertainty sets we derive a closed form portfolio rule based on a worst case max min criterion then in a market where all investors are ambiguity averse mean variance investors with access to given mean return and variance covariance estimates we investigate conditions regarding the existence of an equilibrium price system and give an explicit formula for the equilibrium prices in addition to the usual equilibrium properties that continue to hold in our case we show that the diffidence of investors in a homogeneously diffident with bounded diffidence mean variance investors market has a deflationary effect on equilibrium prices with respect to a pure mean variance investors market in equilibrium deflationary pressure on prices may also occur if one of the investors in an ambiguity neutral market with no initial short position decides to adopt an ambiguity averse attitude we also establish a capm like property that reduces to the classical capm in case all investors are ambiguity neutral

a general mean variance approximation to expected utility for short holding periods the mean variance model is precisely consistent with the expected utility hypothesis only in the special cases of normally distributed security returns or quadratic utility functions there is little evidence however that security returns follow normal distributions see 13 for references and quadratic preferences can be shown to generate implausible results exhibiting increasing absolute risk aversion in the pratt ll arrow 1 2 sense and displaying negative marginal utility after some finite wealth level in addition hakansson 4 has shown that single period mean variance efficient portfolios can have disastrous consequences over time even when return distributions are stationary such criticisms of the mean variance approach within the von neumann morgenstern framework have prompted several writers to suggest that investors maximize the expected value of utility functions with more realistic properties while others have criticized the single period focus of the model one popular alternative utility function is the logarithmic function which exhibits decreasing absolute risk aversion and conveniently leads to myopic decision processes through time i e investors treat each period as if it were the last basing investment decisions on that period s wealth and return distributions only 8 4 other utility functions with constant relative risk aversion such as the power function also imply myopic decision rules within a multiperiod setting

necessity as the mother of invention monetary policy after the crisis we examine recent changes in monetary policy due to the financial crisis and ask whether they are likely to be temporary or permanent we present evidence from two original surveys one of central bank governors the other of academic specialists we find that central banks in crisis countries are more likely to have resorted to new policies to have had discussions about changing mandates and to have communicated more extensively but thinking has changed more broadly for instance many central banks in non crisis countries also report implementing macro prudential measures looking forward we expect central banks to have broader mandates use macro prudential tools more widely and communicate more actively than before the crisis while there is no consensus yet about the usefulness of unconventional monetary policies we expect most of them will remain in central banks toolkits as governors who gain experience with a particular tool are more likely to assess that tool positively finally the relationship between central banks and their governments might well have changed with central banks crossing the line into the political realm more often than in the past

an alternative test of the capital asset pricing model reply in our 1980 paper we tested the joint hypothesis that prices are determined by the mean variance mv capital asset pricing model capm and that beliefs are stationary by focusing on the invariance law of prices we avoided the questionable practice of estimating ex ante expectations with ex post returns moreover we circumvented the need to identify the true market portfolio and hence avoided the ambiguity noted by richard roll 1977 in the traditional security market line sml tests of the same joint hypothesis however stuart turnbull and ralph winter t w and richard sweeney point to a further inconsistency in the joint hypothesis that they believe can be removed by relaxing the stationarity assumption this new concern is fundamental in that it applies to all empirical tests which assume stationarity of the return distribution whether they are simply tests of the capm or tests employing the capm the concern would apply a fortiori to tests that assume stationary betas as well both comments also suggest that the ad hoc addition of a random error term to our invariance law equation and the subsequent statistical tests of it are unnecessary we first address these two criticisms and then address some further criticisms raised separately by t w and sweeney

institutional investors and the qe portfolio balance channel the operation of the portfolio balance channel has been emphasized by monetary policy makers as a key channel through which quantitative easing qe policies work we assess whether the investment behavior of insurance companies and pension funds in the united kingdom during the global financial crisis was consistent with such an effect by analyzing both sectoral and institution level data our results suggest qe led to institutional investors shifting their portfolios away from government bonds towards corporate bonds but did not lead to a shift into equities

saving rates and poverty the role of conspicuous consumption and human capital poor families around the world spend a large fraction of their income consuming goods that do not appear to alleviate poverty while saving at low rates we suggest that individuals care about economic status and interpret this behaviour as conspicuous consumption intended to provide a signal about unobserved income we show that if human capital is observable and correlated with income then a signalling equilibrium in which poor individuals tend to spend a large fraction of their income on conspicuous consumption can emerge this equilibrium gives rise to an increasing marginal propensity to save that might generate a poverty trap

a minimax portfolio selection strategy with equilibrium a new minimax model on optimal portfolio selection with uncertainty of both randomness and estimation in inputs is established and the corresponding optimal portfolio is derived analytically based on this result a sufficient condition for the existence and uniqueness of a nonnegative equilibrium price system under which the total demand and supply of each asset are equal is provided and an explicit formula for such a price system is obtained furthermore some properties of the equilibrium are discussed

normality solvency and portfolio choice this paper examines whether investors with power utility functions choose mean vari ance mv efficient portfolios when returns are approximately normally distributed and there is borrowing or lending at a riskless interest rate the results show that the unlevered portfolios of power utility investors plot very closely to the mv efficient frontier how ever there are marked differences in the mix of risky assets regardless of whether the portfolios are highly concentrated or widely diversified such differences allow power investors to remain solvent even when they lever their optimal portfolios to a greater ex tent than less risk averse mv investors who risk bankruptcy it is concluded that the investment policies of power utility and mv investors with similar risk aversion measures are not as similar as is commonly believed this is particularly true for high power inves tors unless explicit solvency constraints are imposed on the mv problem and for low power investors when quadratic utility approximations are made to the power utility func tions these differences in the investment policies of power utility and mv investors lead us to question the widely accepted assertion that the assumptions of homogeneous beliefs normality a riskless asset and risk averse investors imply the simple mv capm where all investors including power utility investors hold combinations ofthe market portfolio and the riskless asset

how economic contractions and expansions affect expenditure patterns in this study we attempt to understand how household budget allocations across various expenditure categories change when the economy is in recession or expansion the common assumption is that a household s tastes would not change as a function of economic conditions and therefore any adjustments in expenditure patterns during economic contractions expansions would simply be due to changes in the consumption budget standard economic models translate these budgetary effects into lateral movements along a set of fixed engel curves which relate category expenditure shares to total expenditures we propose and test a conceptual framework based on the notion of relative consumption which prescribes that for any given total consumption budget expenditure shares for positional goods services will decrease during a recession while shares for nonpositional goods services will increase i e shifting the entire engel curve upward or downward depending on the nature of the expenditure category and the economic conditions

exact arbitrage pricing and the minimum variance frontier the author examines the relationship between the arbitrage pricing theory of ross and mean variance analysis in particular conditions are derived on the vector of the factor risk premia that are equivalent to the existence of a strictly positively weighted portfolio on the minimum variance frontier also a sufficient condition is given under which the existence of a positive minimum variance portfolio of all the assets in the economy will imply the existence of a positive minimum variance portfolio on a subset this means that rejection of the hypothesis of the existence of a positive minimum variance portfolio on a subset satisfying this condition implies rejection for the whole set a growing body of literature explores the relationship between the arbitrage pricing theory apt of ross 13 14 and the mean variance model among the early work in this direction were the papers of chamberlain and rothschild 2 and chamberlain 1 these papers examine a sequence of economies and characterize the relationship in the limit between the mean and portfolio cost functionals and the minimum variance frontier chamberlain 1 also gives a condition under which exact arbitrage pricing will hold dybvig 4 and grinblatt and titman 7 examine equilibrium models in an apt context for a finite economy they derive sharp bounds on the deviation from exact arbitrage pricing recent papers by huberman kandel and stambaugh 9 and grinblatt and titman 8 explore the relationship between the apt and the mean variance model by studying portfolios that can be used as proxies for the factors and examining the relationship these portfolios bear to the minimum variance frontier these two papers also deal with equilibrium models in spite of the number and variety of equilibrium apt models the question of the pricing of factor risk in equilibrium remains largely unexplored this paper makes some progress in addressing that issue by looking at a given equilibrium restriction and studying the constraints it imposes on the vector of factor premia itself the most familiar equilibrium restriction we might study is the central implication of the capital asset pricing model capm that the market portfolio is efficient in particular no portfolio with the same expected return as the market portfolio has a smaller variance the restriction we actually study is weaker than

on the sensitivity of mean variance efficient portfolios to changes in asset means some analytical and computational results tbis paper investigates the sensitivity of meanvariance mv efficientportfolios to changes in the means of individual assets when only a budget constraint is imposed on the investment problem the analytical results indicate that an mv efficient portfolio s weights mean and variance can be extremely sensitive to cbanges in asset means when nonnegativity constraints are also imposed on the problem the computational results confirm that a positively weigbted mv efficient portfolio s weigbts are extremely sensitive to cbanges in asset means but the portfolio s returns are not a surprisingly small increase in the mean of just one asset drives balf the securities from the portfolio yet the portfolio s expected return and standard deviation are virtually uncbanged this paper supersedes should investors hold well diversified portfolios financial support from the natural science and engineering research council of canada is gratefully acknowledged we also acknowledge the most capable assistance of ruth cornale simon ng jean marc potier and frederick shen the paper was presented at simon fraser university and the western finance association meetings in san diego we thank the participants especially stephen brown john herzog john heaney ray koopman and bruce lehmann and the editors jon ingersoll and chester spatt for

are positional concerns stronger in some domains than in others for more than one hundred years economists have discussed the concept of positional goods that the utility conferred by many perhaps even most goods depends not only on the amount the individual consumes but also on the amount others consume e g thorstein veblen 1899 james duesenberry 1949 john k galbraith 1958 robert frank 1985 while economic interest in positional goods is increasing e g mark pingle and mike mitchell 2002 kenneth arrow et al 2004 ed hopkins and tatiana kornienko 2004 the literature remains largely theoretical rather than empirical if status concerns affect all items in the utility function equally leisure as well as goods the positional effect would operate like a lump sum tax reducing well being without changing the allocation of time or money arrow et al 2004 however if positional concerns are stronger for some things than for others then in order to understand how people can become better off in well being not simply in wealth we must investigate how interpersonal competition interacts with material gains frank 1997 evidence about what goods are more positional than others is essential for correct policy recommendations gregory besharov 2002 but little is actually known about the relative positional rankings of items in the typical consumer s utility function four hypotheses proposed in the literature are

keeping up with the joneses and optimal diversification abstract peer effects have been shown to affect behavior and can generally lead to investments choices that are mean variance inefficient this paper analyzes optimal diversification with peer effects we show that if individuals have keeping up with the joneses preferences and they take their peer group reference as the market portfolio markowitz s mean variance efficiency analysis and the capm equilibrium are intact this holds for any keeping up preferences as well as heterogeneous combinations of such preferences these results also extend to the merton levy segmented market model

a test of conspicuous consumption visibility and income elasticities abstract this paper shows that consistent with a signaling by consuming model a la veblen income elasticities can be predicted from the visibility of consumer expenditures we outline a stylized conspicuous consumption model where income elasticity is endogenously predicted to be higher if a good is visible and lower if it is not we then develop a survey based measure of expenditure visibility ranking different expenditures by how noticeable they are to others finally we show that our visibility measure predicts up to one third of the observed variation in elasticities across consumption categories in u s data

bayes stein estimation for portfolio analysis in portfolio analysis uncertainty about parameter values leads to suboptimal portfolio choices the resulting loss in the investor s utility is a function of the particular estimator chosen for expected returns so this is a problem of simultaneous estimation of normal means under a well specified loss function in this situation as stein has shown the clas sical sample mean is inadmissible this paper presents a simple empirical bayes estimator that should outperform the sample mean in the context of a portfolio simulation analysis shows that these bayes stein estimators provide significant gains in portfolio selection problems

evaluating the impact of inequality constraints and parameter uncertainty on optimal portfolio choice we present new analytical results for the impact of portfolio weight constraints on an investor s optimal portfolio when parameter uncertainty is taken into account while it is well known that parameter uncertainty and imposing weight constraints results in reduced certainty equivalent returns in the general case there are no analytical results in a special case commonly used in the funds management literature we derive analytical expression for the certainty equivalent loss that does not depend on the risk aversion parameter we illustrate our theoretical results using hedge fund data from the perspective of a fund of fund manager our contribution is to formalize the framework to investigate this problem as well as providing tractable analytical solutions that can be implemented using either simulated or asset manager returns

determinants of levered portfolio performance the cumulative return to a levered strategy is determined by five elements that fit together in a simple and useful formula a previously undocumented element is the covariance between leverage and excess return to the fully invested source portfolio underlying the strategy in an empirical study of volatility targeting strategies over the 84 year period 1929 2013 this covariance accounted for a reduction in return that substantially diminished the sharpe ratio in all cases

market efficiency a theoretical distinction and so what with the aid of some simplifying assumptions the capital asset pricing model comes to dramatic conclusions about practical matters such as how to choose an investment portfolio and how to value financial assets as illustrated in this article when one particular clearly unrealistic capm assumption is replaced by a more real world version some of the dramatic practical conclusions of capm no longer follow this result has implications for financial practice research and pedagogy

the continuing muddles of monetary theory a steadfast refusal to face facts lionel robbins was concerned about the methodology of economic science when he discussed the relationship between theory and reality two of the examples of inappropriate relationships were taken from monetary economics such shortcomings continue among the worst are 1 is lm whereby the monetary authorities set the monetary base and the interest rate is market determined 2 the monetary base multiplier of bank deposits and the role of reserve ratios 3 the current three equation neoclassical consensus assuming perfect creditworthiness and hence no need for banks 4 the analysis of the evolution of money

portfolio optimization with factors scenarios and realistic short positions this paper presents fast algorithms for calculating mean variance efficient frontiers when the investor can sell securities short as well as buy long and when a factor and or scenario model of covariance is assumed currently fast algorithms for factor scenario or mixed factor and scenario models exist but except for a special case of the results reported here apply only to portfolios of long positions factor and scenario models are used widely in applied portfolio analysis and short sales have been used increasingly as part of large institutional portfolios generally the critical line algorithm cla traces out mean variance efficient sets when the investor s choice is subject to any system of linear equality or inequality constraints versions of cla that take advantage of factor and or scenario models of covariance gain speed by greatly simplifying the equations for segments of the efficient set these same algorithms can be used unchanged for the long short portfolio selection problem provided a certain condition on the constraint set holds this condition usually holds in practice

portfolio optimization under a minimax rule this paper provides a new portfolio selection rule the objective is to minimize the maximum individual risk and we use an l function as the risk measure we provide an explicit analytical solution for the model and are thus able to plot the entire efficient frontier our selection rule is very conservative one of the features of the solution is that it does not explicitly involve the covariance of the asset returns

a half century of returns on levered and unlevered portfolios of stocks bonds and bills with and without small stocks in two earlier papers grauer and hakansson 1982 grauer and hakansson 1984 we applied the multiperiod portfolio theory of mossin 1968 hakansson 1971 1974 leland 1972 ross 1974 and huberman and ross 1983 to the construction and rebalancing of portfolios composed of u s stocks corporate bonds government bonds and a risk free asset borrowing was ruled out in the first article while margin purchases were permitted in the second the probability distributions used were naively estimated from past realized returns in ibbotson this paper applies multiperiod portfolio theory to the construction and rebalancing of portfolios composed of u s stocks corporate bonds government bonds and a risk free asset with small stocks included as a separate investment vehicle probability assessments are based on the past joint empirical distribution our principal findings are 1 small stocks while totally ignored at times entered even the most riskaverse portfolios most of the time and 2 small stocks when chosen tended to replace common stocks except in the 1970s and early 1980s when they were primarily held in lieu of the risk free asset presented at the australian graduate school of management and at macquarie university both in sydney southern methodist university duke university the university of southern california the london graduate school of business and the annual meeting of the western financo association in scottsdale arizona the authors thank the participants of these seminars especially michael brennan and ehud ronn for helpful comments financial support from the social sciences and humanities research council of canada and the financial research foundation of canada is gratefully acknowledged the authors also wish to thank changwoo lee for research assistance and are greatly indebted to frederick shen for computational assistance

qe a successful start may be running into diminishing returns existing studies may have underestimated the impact of qe1 on uk gdp because they did not take full account of the beneficial effect on credit risk spreads and on the exchange rate however all such effects were also influenced by the roughly simultaneous introduction of similar easing in the usa which complicates the analysis another area where qe has been positive is in reducing public sector borrowing costs where qe1 and subsequent rounds have disappointed is in their inability to stimulate a recovery in credit and monetary growth amid an increased desire among banks to hold far more of their reserves at the central bank moreover there is growing evidence of significant diminishing returns in qe2 as gilt rates have already fallen to historically low levels and the risk is that if policy makers fail to resuscitate the bank lending channel further rounds of qe could potentially have negative returns

conspicuous consumption and race evidence from south africa abstract a century ago thorstein veblen introduced socially contingent consumption into the economic literature this paper complements the scarce empirical literature by testing his conjecture on south african household data and finds that black and coloured households spend relatively more on visible consumption than comparable white households following the approach of charles et al 2009 this paper explores whether the differences in visible expenditures can be explained with a signaling model of status seeking moreover it is assessed to which extent positional concerns motivate conspicuous consumption although the socially contingent share in visible consumption increases with income different incentives to consume conspicuously seem to explain that at every level of income black households spend relatively more on visible consumption than comparable white households in contrast to the findings of charles et al 2009 where differential spending on conspicuous consumption can be found also within each group separately the model s core hypothesis fails to hold within the group of white south africans

global income distributions and inequality 1993 and 2000 incorporating country level inequality modeled with beta distributions abstract using a method of moments estimator flexible three parameter beta distributions are fitted to aggregate country level income data to overcome an untenable assumption of previous studies that persons within each income group receive the same income regional and global income distributions are derived as weighted mixtures of country specific distributions analytical expressions for gini and theil s measures of inequality at country regional and global levels are derived in terms of the parameters of the beta distributions application to data for 91 countries in 1993 and 2000 reveals a high degree of global inequality with evidence of declining inequality largely attributable to growth in china

international transmission channels of u s quantitative easing evidence from canada en reaction a la grande recession la reserve federale americaine a reduit son taux directeur a sa valeur plancher afin d accentuer la detente monetaire la banque centrale americaine a par la suite mis en oeuvre des achats massifs d actifs ce qui a eu pour effet de quadrupler la taille de son bilan

conspicuous consumption and race using nationally representative data on consumption we show that blacks and hispanics devote larger shares of their expenditure bundles to visible goods clothing jewelry and cars than do comparable whites these differences exist among virtually all subpopulations are relatively constant over time and are economically large although racial differences in utility preference parameters might account for a portion of these consumption differences we emphasize instead a model of status seeking in which conspicuous consumption is used as a costly indicator of a household s economic position using merged data on race and state level income we demonstrate that a key prediction of the status signaling model that visible consumption should be declining in reference group income is strongly borne out in the data for each racial group moreover we show that accounting for differences in reference group income characteristics explains most of the racial difference in visible consumption

the capital asset pricing model in economic perspective the capital asset pricing model capm is theoretically incomplete in its demand side focus risk averse investors and internally inconsistent homogeneous beliefs is not conclusively supported empirically and yet it legitimizes a notion that investors can earn higher returns by bearing undiversifiable risk our article does not merely extend the capm with more realistic assumptions it completes its original framework by including 1 risk taking investors in the investor population 2 investors who can have heterogeneous expectations or beliefs an overlooked but required condition for the capm to be an internally consistent and meaningful model of competitive financial asset pricing under uncertainty and 3 a positive sloped short run supply curve based on a reasonable interpretation of the nature of financial asset trade upon a complete economic interpretation it is shown that the equilibrium systematic risk rate of return relationship depends on whose aggregate trading activity dominates ri

there is no silver bullet the value of diversification in planning invasive species surveillance abstract in this study we demonstrate how the notion of diversification can be used in broad scale resource allocation for surveillance of invasive species we consider the problem of short term surveillance for an invasive species in a geographical environment we find the optimal allocation of surveillance resources among multiple geographical subdivisions via application of a classical portfolio framework which allocates investments among multiple financial asset types with uncertain returns in a portfolio that maximizes the performance and by meeting the desired diversification targets protects against errors in estimating the portfolio s performance we illustrate the approach with a case study that applies a spatial transmission model to assess the risk of spread of the emerald ash borer eab a significant pest in north america with infested firewood that may be carried by visitors to campground facilities in central canada adding the diversification objective yields an expected survey performance that is comparable with undiversified optimal allocation but more importantly makes the geographical distribution of survey priorities less subject to possible errors in the spread rate estimates overall diversification of pest surveillance can be viewed as a viable short term strategy for hedging against uncertainty in expert and model based assessments of pest invasion risk

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

how many stocks make a diversified portfolio we show that a well diversified portfolio of randomly chosen stocks must include at least 30 stocks for a borrowing investor and 40 stocks for a lending investor this contradicts the widely accepted notion that the benefits of diversification are virtually exhausted when a portfolio contains approximately 10 stocks we also contrast our result with the levels of diversification found in studies of individuals portfolios

the benefits of differential variance based constraints in portfolio optimization abstract the main problem of portfolio optimization is parameter estimation error various methods have been suggested to mitigate this problem among which are shrinkage resampling bayesian updating naive diversification and imposing constraints on the portfolio weights this study suggests two substantial extensions of the constrained optimization approach the variance based constraints vbc and the global variance based constraints gvbc methods by the vbc method the constraint imposed on the weight of a given stock is inversely proportional to its standard deviation the higher a stock s sample standard deviation the higher the potential estimation error of its parameters and therefore the tighter the constraint imposed on its weight gvbc employs a similar idea but instead of imposing a sharp boundary constraint on each stock a quadratic cost is assigned to deviations from the naive 1 n weight and a single global constraint is imposed on the total cost of all deviations comparing ten optimization methods we find that the two new suggested methods typically yield the best performance as measured by the sharpe ratio gvbc ranks first these results are obtained for two different datasets and are also robust to the number of assets under consideration

novelty preferences and fashion when goods are unsettling abstract there is a whole class of goods those semi durable and durable conveniences for which efficiency and functionality seem not to be the main characteristics of appeal but rather the variability they display in their design properties and in their connections with other goods these goods have not been much dealt with in economics yet these are the goods whose new variants households seem to consume in numbers to which consumers become addicted and in which fashions appear and disappear in this paper i offer a framework for understanding these phenomena without having to resort to one or another form of irrationality on the part of consumers the rationality i suggest however has to include also the cognitive and affective problems that arise when novelty appears

running to keep in the same place consumer choice as a game of status if individuals care about their status defined as their rank in the distribution of consumption of one positional good then the consumer s problem is strategic as her utility depends on the consumption choices of others in the symmetric nash equilibrium each individual spends an inefficiently high amount on the status good using techniques from auction theory we analyze the effects of exogenous changes in the distribution of income in a richer society almost all individuals spend more on conspicuous consumption and individual utility is lower at each income level in a more equal society the poor are worse off

portfolio selection in a data rich environment we model portfolio weights as a function of latent factors that summarize the information in a large number of economic variables this approach hereafter diffusion index approach offers the opportunity to exploit a much richer information base to improve portfolio selection we use factor analysis to estimate the space spanned by the factors this provides consistent estimates for the optimal weights as the number of economic variables and sample size go to infinity we consider an empirical application to illustrate the practical usefulness of our approach the results indicate that the diffusion index approach helps to improve the portfolio performance

impossible frontiers a key result of the capital asset pricing model capm is that the market portfolio the portfolio of all assets in which each asset s weight is proportional to its total market capitalization lies on the mean variance efficient frontier the set of portfolios having mean variance characteristics that cannot be improved upon therefore the capm cannot be consistent with efficient frontiers for which every frontier portfolio has at least one negative weight or short position we call such efficient frontiers impossible and show that impossible frontiers are difficult to avoid in particular as the number of assets n grows we prove that the probability that a generically chosen frontier is impossible tends to one at a geometric rate in fact for one natural class of distributions nearly one eighth of all assets on a frontier is expected to have negative weights for every portfolio on the frontier we also show that the expected minimum amount of short selling across frontier portfolios grows linearly with n and even when short sales are constrained to some finite level an impossible frontier remains impossible using daily and monthly u s stock returns we document the impossibility of efficient frontiers in the data

sensitivity analysis for mean variance portfolio problems this paper shows how to perform sensitivity analysis for mean variance mv portfolio problems using a general form of parametric quadratic programming the analysis allows an investor to examine how parametric changes in either the means or the right hand side of the constraints affect the composition mean and variance of the optimal portfolio the optimal portfolio and associated multipliers are piecewise linear functions of the changes in either the means or the right hand side of the constraints the parametric parts of the solution show the rates of substitution of securities in the optimal portfolio while the parametric parts of the multipliers show the rates at which constraints are either tightening or loosening furthermore the parametric parts of the solution and multipliers change in different intervals when constraints become active or inactive the optimal mv paths for sensitivity analyses are piecewise parabolic as in traditional mv analysis however the optimal paths may contain negatively sloping segments and are characterized by types of kinks i e points of nondifferentiability not found in mv analysis

interactive decision system in stochastic multiobjective portfolio selection abstract some investors pursuing a high return at the relatively high risk of losing a part of their money do not always select a preferred portfolio from among the so called mean variance efficient frontier provided by markowitz 1959 portfolio selection wiley new york chue and nagasawa 1996 an investor modeling and interactive method in multiobjective portfolio selection proceedings of the pacific conference on manufacturing 96 constructed their own investor model based on an risk permission maximum return portfolio and proposed an interactive portfolio selection system for selecting a preferred portfolio from the set of candidate portfolios this paper extends the system to the case when the mean and the variance of return of securities have several scenarios with known occurrence probabilities

social norms savings behavior and growth we argue that many goods and decisions are not allocated or made through markets we interpret an agent s status as a ranking device that determines how well he or she fares in the nonmarket sector the existence of a nonmarket sector can endogenously generate a concern for relative position in for example the income distribution so that higher income implies higher status moreover it can naturally yield multiple equilibria it is thus possible to explain differences in growth rates across countries without recourse to differences in underlying preferences technologies or endowments different social organizations lead to different reduced form preferences which lead to different growth rates

positively weighted portfolios on the minimum variance frontier duality theory is employed to provide necessary and sufficient conditions for portfolios on the minimum variance frontier to have positive investment proportions in all assets these conditions involve the feasibility of portfolios that have non negative correlation with all assets and positive correlation with at least one using these results several qualitative results concerning the signs of investment proportions in efficient portfolios are proved it is argued that the conditions that ensure all positive weights in efficient portfolios are intuitively compelling and are not unique to the capm with large numbers of assets however the signs of weights in minimum variance portfolios can be very sensitive to slight departures from these conditions due to for example sampling error the behavior of the minimum variance frontier is of general concern to portfolio theory and plays a central role in the study of asset pricing an unresolved question in the theory of the minimum variance frontier involves when it will contain portfolios with positive weights on all assets this paper addresses that question we show that the conditions that ensure positive investment proportions in efficient portfolios have by farkas lemma a simple dual this dual or alternative system of inequalities puts conditions directly on the variances covariances and means of the returns and these conditions can be interpreted intuitively this contrasts with simply considering the first order conditions for variance minimization since these involve the inverted covariance matrix with a large number of assets it can be difficult to translate one s intuitive sense about how assets covary into statements about the inverse of the covariance matrix the duality conditions we derive involve the existence of portfolios that are positively or negatively correlated with all assets indeed we show that a necessary and sufficient condition for no portfolio on the frontier to have all positive weights is the feasibility of an arbitrage or hedge portfolio with weights that sum to zero that has an expected payoff of zero and has non negative correlation with all assets the duality conditions also make it easy to construct examples of the types of covariability that permit or preclude positive investment proportions on all assets in frontier portfolios there are at least three apparent reasons for interest in the signs of weights

how does the diversity of investors beliefs affect stock price informativeness abstracta growing number of studies have investigated the role of stock prices in aggregating private information and guiding resource reallocation however this article may be the first attempt to study how the diversity of beliefs affects stock price informativeness the framework of the noisy rational expectations model shows that stock informativeness is determined by both the precision and use of private information in trading if private beliefs about the value are highly diverse the aggregate average opinion revealed in a stock s price will be more accurate and thus more informative as the price becomes more informative however individual investors will rely less on their private information when this occurs less private information will be absorbed in price which in turn reduces price informativeness our model shows that the relationship between belief diversity and price informativeness is u shaped in equilibrium

unconventional monetary policy the assessment the uncon ventional monetary policy measures adopted by the major central banks in the period since 2008 are discussed in this paper we highlight some important differences between quan titative easing and conventional monetary policy and then evaluate the mechanisms through which quantitative easing may propagate to financial markets and the real economy drawing on perspec tives from monetarist and new keynesian theory additional measures intended to supplement or strengthen the effects of pure quantitative easing often termed unconventional unconventional monet ary policy are also assessed in our discussion we relate the various articles in this issue to some of the key research questions posed in relation to unconventional monetary policy

the equilibrium distribution of income and the market for status this paper explores the implications for risk taking behavior and the equilibrium distribution of income of assuming that the desire for status positions is a powerful motive and that it raises the marginal utility of consumption in contrast to previous analyses we consider the case in which status positions are sold in a hedonic market we show that such a complete hedonic market in status positions can be perfectly replicated by a simpler arrangement with a status good and a social norm that assigns higher status to those that consume more of this good the main result is that for a wide range of initial conditions the equilibrium distribution over income status and consumption is the same that this allocation requires inequality of income and consumption and that this allocation coincides with the optimum of a utilitarian planner

an analytic derivation of admissible efficient frontier with borrowing the admissible efficient portfolio selection problem for risky assets has been discussed by zhang and nie in this paper the admissible efficient portfolio model is proposed under the assumption that there exists the borrowing money or a risk free asset case the admissible efficient frontiers are developed by the spreads of expected return and risk from admissible errors the analytic forms of the admissible efficient frontiers when short sales are not allowed on all risky assets are derived from two cases the borrowing with an upper bound constraint or without an upper bound constraint the influence on the admissible efficient frontier is explained under the different interest rates of the borrowing the differences between the results with the borrowing and the results without the borrowing is revealed by a real numerical example

will my risk parity strategy outperform the authors gauged the return generating potential of four investment strategies value weighted 60 40 fixed mix and unlevered and levered risk parity they report three main findings 1 even over periods lasting decades the start and end dates of a backtest can have a material effect on results 2 transaction costs can reverse ranking especially if leverage is used and 3 a statistically significant return premium does not guarantee outperformance over reasonable investment horizons see comments and response on this article

comparison of alternative utility functions in portfolio selection problems this paper examines the effect of alternative utility functions and parameter values on the optimal composition of a risky investment portfolio normally distributed assets are the setting for the theoretical and empirical analyses the results agree well with the available theory and imply utility functions and parameter values that are appropriate for investors with particular risk bearing attitudes the results give strong empirical support to the proposition that utility functions having different functional forms and parameter values but similar absolute risk aversion indices have similar optimal portfolios these results suggest that over horizons up to one year one can safely substitute convenient surrogate utility functions for other utility functions for reasons of tractability or otherwise the results also provide guidance regarding the significance of the magnitude and change of particular numerical values of the risk aversion index moreover theoretical exact results are obtained using rubinstein s measure of global risk aversion

sovereign debt the assessment this article serves as an introduction to two issues of the oxford review of economic policy one entitled sovereign debt understanding bond markets during the eurozone crisis and the second sovereign debt lessons from the past reforms for the future we begin by documenting recent trends in advanced country sovereign indebtedness and reviewing events that preceded the sovereign debt crisis in the eurozone the mechanisms through which rising sovereign debt may impact bond yields economic growth and inflation are discussed and the evidence for such effects is reviewed our discussion highlights that there is no unique threshold beyond which sovereign debt exerts adverse macroeconomic effects and that in order to understand the consequences of a given debt load one must analyse its structure in terms of internal and external creditors currency denomination the time to maturity of the bonds and the legal code governing debt issuance as well as various economic and political constraints measuring the fiscal space of the sovereign we then turn our attention to episodes in which sovereign debt proves excessive and default occurs we review explanations for the protracted and inefficient nature of defaults and describe some lessons from historical studies examining default outcomes in the final part of the paper we discuss proposals for averting future debt crises including jointly issued bonds such as eurobonds contingent convertible bonds and elements of a sovereign debt restructuring mechanism in the course of our discussion we draw on each of the 11 articles included in the two issues of this journal devoted to sovereign debt copyright 2013 oxford university press

identification of endogenous social effects the reflection problem this paper examines the reflection problem that arises when a researcher observing the distribution of behaviour in a population tries to infer whether the average behaviour in some group influences the behaviour of the individuals that comprise the group it is found that inference is not possible unless the researcher has prior information specifying the compisition of reference groups if this information is available the prospects for inference depend critically on the population relationship between the variables defining reference groups and those directly affecting outcomes inference is difficult to implossible if these variables are functionally dependent or are statistically independent the prospects are better if the variables defining reference groups and those directly affecting outcomes are moderately related in the population

quantitative easing is not as unconventional as it seems policy interest rates do not have to be short the means by which monetary authorities influence prices and quantities can differ but the obstacles to altering one rather than the other are not insuperable inflation is sluggish and expectations of future interest rates long and short nominal and real are diverse and uncertain these factors determine the limited power that monetary authorities enjoy when they conduct quantitative easing but this policy is not as unconventional as some have claimed and indeed can be viewed as broadly similar to conventional monetary measures the impact of quantitative easing however could be very different depending on the underlying structure of the economy and the fiscal authorities responses finally we note some important caveats that must be borne in mind when trying to evaluate the impact of quantitative easing particularly given the fact that the world s main financial markets are closely linked copyright 2012 oxford university press

conspicuous spending and the income distribution of social groups using south african household expenditure data we analyze how the spending of a household on visible goods such as jewelry and clothes depends on the distribution of income within its social group we find that this spending is positively correlated with the share of peers who possess a similar income level to the household what we dub the local income share moreover we find that the spending of a household on visible goods is positively correlated with the average income of peers that are poorer than this household we interpret this as evidence for cascade effects through which income changes among the poorest in the social group can trigger adjustments in the visible spending patterns of the wealthy in line with previous research charles et al 2009 we also find that visible spending of a household is negatively correlated with the average income of its social group we present a simple model of status competition based on hopkins and kornienko 2004 that synthesizes these effects and can account for our results jel d12 d31 o12

dea frontier improvement and portfolio rebalancing an application of china mutual funds on considering sustainability information disclosure abstract data envelopment analysis dea has been a widely used methodology for evaluating the relative performance of portfolios extensive work has appeared for realizing the role of dea in the aspect of assessing portfolio performance and deriving the relative rankings however the role of providing realizable benchmarks is not fully explored in the existing literatures most importantly the dea based portfolio performance evaluation methods developed in the existing literatures can hardly provide support for fund managers in pursuing sustainability performance in this paper we first propose a dea frontier improvement approach under the mean variance framework this approach provides investor with a rebalancing strategy as well as an improved dea frontier which approximates the portfolio efficient frontier better than the traditional dea model does then this approach is extended to a general return risk framework our in sample simulation results verify the effectiveness of the proposed approach for a wide range of applications in addition the out of sample tests show that the rebalancing investment strategies can achieve higher sharpe ratios and sortino ratios than those of the original ones finally we apply the proposed approach to evaluate mutual fund performance in china with the consideration of sustainability information disclosure we construct a disclosure index to indicate the extent of sustainable information disclosure of each mutual fund the results show that the proposed approach provides not only investment recommendations but also references for constructing sustainable green funds

capital asset pricing compatible with observed market value weights we show that the set of expected return vectors for which an observed portfolio is mean variance mv efficient is a two parameter family we identify ten ways to specify the time series behavior of the two parameters the result highlights a number of inconsistencies involved in mv modelling for each of the cases it permits the inference of the time series of expected return vectors as well as all the other capital asset pticing model capm variables compatible with a known covariance matrix and the observed time series of market value weights the empirical work shows that there are substantial case to case differences in the time series of mean vectors and many of them are quite different from the constant mean vector envisioned in tests of

international portfolio diversification with estimation risk international portfolio diversification has long been advocated as a way of enhancing average returns while reducing portfolio risk for the investor who considers diversifying into foreign securities this proposition however relies on the assumption that the required inputs to the classical mean variance analysis are known with certainty typically expected returns variances and covariances are simply replaced by their ex post sample values and the optimal portfolio is derived without mentioning the uncertainty inherent in these parameter values but the rational investor should take this uncertainty into account when forming expectations and probably will consider estimators that are less subject to estimation error than the classical sample mean this paper investigates alternative estimators of expected returns and their implications for the alleged gains from diversification an important observation is the crucial influence that errors in estimating expected returns have on portfolio analysis a closer examiprevious studies of international portfolio diversification have relied on ex post meanvariance analysis without considering the problem of estimation risk typically past averages are substituted for expected returns and no allowance is made for the uncertainty inherent in these parameter values first i demonstrate the shortcomings of such an approach and second i investigate another method of estimating expected returns initially proposed by stein by shrinking the sample averages toward a common mean i find that the out of sample performance of the optimal portfolio is substantially increased one of the implications of this method is that the classical conclusions vastly overestimate the possible gains in average returns instead benefits from diversification are more likely to accrue from a reduction in risk this paper draws on part of my dissertation at the university of chicago i am grateful to arnold zellner michael mussa george constantinides and especially john bilson for useful discussions and comments numerous improvements were also suggested by the referee this research received the generous financial support of the college interuniversitaire d etudes doctorales dans les sciences du management

on correlations and inferences about mean variance efficiency a framework is presented for investigating the mean variance efficiency of an unobservable portfolio based on its correlation with a proxy portfolio a sensitivity analysis derives the highest correlation between the proxy and a portfolio that reverses the inference of a test of sharpe lintner tangency for example the maximum correlation between the value weighted nyse amex portfolio and a portfolio inferred tangent ranges from 0 76 to 0 48 we also test whether the correlation between the proxy and the tangent portfolio exceeds a given level this hypothesis is often rejected for the nyse amex proxy at a correlation of 0 7

investment policy implications of the capital asset pricing model the results of previous generalized security market line sml tests of the mean variance mv and linear risk tolerance lrt capital asset pricing models indicate that the models are empirically identical a very widely accepted but technically incorrect explanation for the results is that with normal return distributions all expected utility maximizing risk averse investors will pick mv portfolios the paper shows that the generalized sml tests cannot distinguish between the mv model and a much wider variety of power utility lrt models than has previously been entertained on the other hand with approximately normal or real world return distributions the investment policies of the various models are shown to be different from each other and from the mv policy in particular to the extent the results of the portfolio selection calculations are robust the results of and implications drawn from the tests of the macro pricing relations are not based on firm micro foundations empirical tests of positive theories of asset pricing have focused primarily on the linear risk return trade off predicted by the mean variance capital asset pricing model mv capm the tests friend and blume 9 black jensen and scholes 2 blume and friend 4 fama and macbeth 7 have provided the model with less than full fledged support moreover from a theoretical view the model suffers from a number of well known deficiencies these two factors have led several authors roll 23 rubinstein 25 26 hakansson 16 and grauer 11 to suggest that one of the power linear risk tolerance lrt utility functions may form the basis of a better positive theory of asset pricing in particular one consistent with risky assets being normal goods but so far the results from more general empirical risk return tests have neither supported nor failed to support the suggestion for example roll 23 based on weekly stock market data from the 1960s attempted to distinguish between the growth optimal capm which is consistent with logarithmic utility only and which in turn can be viewed as a special case of the lrt models and the mv capm by comparing the slopes and intercepts of the generalized security market lines smls predicted by the two models the results indicated that at the macro level the two models were empirically identical in a broader study of linear risk return trade offs that covered the 1934 71 period and employed monthly data grauer 11 did not find

the e v stationarity of secure returns some empirical evidence abstract the joint hypothesis that the expected return vector and the variance covariance matrix of returns are intertemporally stationary is rejected for the monthly return data for securities included on the crsp file this finding is robust in that it is invariant to the type of sampling procedure used and to whether nominal or real security returns are used in contrast the hypothesis that the correlation matrix of returns is intertemporally stationary could not be rejected for the same samples of securities

simulating security markets in dynamic and equilibrium modes an asynchronous discrete time model run in dynamic mode can model the effects on market prices of changes in strategies leverage and regulations or the effects of different return estimation procedures and different trading rules run in equilibrium mode it can be used to arrive at equilibrium expected returns

positional spending and status seeking in rural china focusing on a remote area in rural china we use a panel census of households in 26 villages to show that socially observable spending has risen sharply in recent years we demonstrate that such spending by households is highly sensitive to social spending by other villagers this suggests that social spending is either positional in nature i e motivated by status concerns or subject to herding behavior we also document systematic relations between social spending and changes in higher order terms of the income distribution we find that the implications of status seeking for spending are not unidimensional they vary across income groups and expenditure categories in particular and consistent with theories of rank based status seeking we find that the poor increase spending on funerals and gifts as competition for status intensifies in addition poor families of grooms expend more for wedding ceremonies as local income competition increases while the families of brides do not the welfare implications of spending in order to keep up with the joneses are potentially large particularly for poor households

beta in linear risk tolerance economies this paper employs numerical means to examine i the expected return beta plot in power utility linear risk tolerance lrt economies and ii whether in the power utility economies a valuation equation containing covariance and coskewness terms might better explain expected returns than one containing covariance terms alone the results show that the expected return beta plots constructed from real world return distributions are very similar to the plots found in empirical tests of the mean variance capital asset pricing model mv capm hence a power utility lrt capm may provide a better theory of asset pricing than the mv capm does while beta is not the correct measure of risk in power utility lrt economies the results show that on average a valuation equation containing covariance terms only explains expected returns better than a valuation equation containing both covariance and coskewness terms

improving diversification opportunities for socially responsible investors socially responsible investment sri has grown enormously and has expanded globally in recent years it allows sri investors to reduce their portfolio risk assumptions through international diversification in this context the aim of this paper is twofold i to examine price and volatility linkages among the most representative sri indexes for north america europe and asia pacific employing a multivariate approach and ii to provide the out of sample performance of an optimal portfolio constructed on the basis of time varying return and volatility forecasts from this specification approach our overall results show that using this technique it is possible to reduce risk and out perform the naive rule which is usually employed in this type of investment these findings are relevant not only for academics but also for practitioners especially for professional managers of sri portfolios

status the distribution of wealth private and social attitudes to risk this paper supposes an individual cares about his her own wealth not only directly but also via the relative standing that this wealth induces the implications for risk taking are investigated in particular such a model provides a natural explanation of the concave convex concave utility described by friedman and savage however there are a number of key differences between the present model and any model based on own wealth alone for example an equilibrium wealth distribution here may have a middle class further the status interaction involves an externality and an equilibrium wealth distribution may be pareto inefficient but also about the implied relative standing in the distribution of wealth has a long but checkered history an early exponent of such ideas was of course veblen 1899 it is indeed a notion which most economists reject albeit usually without explicit comment a notable and articulate exception however is frank 1985 for example see also the references frank cites on pp 33 34 it is however a notion with substantial intuitive appeal and it seems useful to ascertain its consequences before coming to a final judgement as to its merits the present paper is concerned with deriving the consequences of such valuation of status for risk taking what seems to be the sharpest possible model is adopted here this assumes that what is essentially ordinal rank in the wealth distribution enters von neumann morgenstern utility as an argument in addi tion to wealth itself thus higher wealth increases utility not only directly but also indirectly via higher status in the interests of both simplicity and drama it is typically assumed here that all individuals have identical utility functions which are concave in wealth but convex in status section 2 discusses how the model provides a natural explanation of the fundamental phenomenon addressed by friedman and savage 1948 that individuals may simultaneously purchase insurance and participate in lotteries although each individual here has a utility function which is concave in wealth itself utility can nevertheless be convex in wealth over some range when the indirect effect via status is included this effect is enhanced by the convexity of utility in status but will follow in any case if increasing wealth entails moving up in status much more rapidly than losing wealth entails moving down it is shown

more possessions more worry abstract a common wisdom asserts that the wider the universe of assets to choose from the greater the investor s welfare we show that this is not the case in practice where parameters have to be estimated even when the estimates are unbiased surprisingly risk aversion plays a crucial role corresponding to the desirability of asset expansion by dividing investors in three groups investors with very low risk tolerance and investors with very high risk tolerance are better off with asset expansion and investors with moderate risk tolerance are worse off despite the option to refrain from investing in the additional asset

the effects of asset purchases and normalization of u s monetary policy this paper examines changes in the effects of unconventional monetary policies in the united states to this end we estimate a markov switching var model with absorbing regimes to capture possible structural changes our results detect regime changes around the beginning of 2011 and the middle of 2013 before 2011 the u s large scale asset purchases lsaps had relatively large impacts on the real economy and prices but after the middle of 2013 their effects were weaker and less persistent in addition after the middle of 2013 which includes the monetary policy normalization period the asset purchase or balance sheet shocks had slightly weaker effects than during the early stage of the lsaps but stronger effects than during the late stage of the lsaps while interest rate shocks had insignificant effects on the real economy and prices finally our results suggest that the positive responses of durables and capital goods expenditures to interest rate shocks weakened the negative impacts of interest rate hikes after the middle of 2013 including the period of monetary policy normalization jel c32 e21 e52

short sales restrictions and kinks on the mean variance frontier with a short sales restriction there may be switching points along the mean variance frontier corresponding to changes in the set of assets held traditional wisdom holds that each switching point corresponds to a kink while ross has claimed that kinks never occur this paper shows that the truth lies between the two views since the efficient frontier may or may not be kinked at a switching point there is some indication that kinks are rare since a kink corresponds to a portfolio in which all assets have the same expected return

gains from international diversification 1968 85 returns on portfolios of stocks and bonds this paper applies the multi period investment model to a universe of international securities on the basis of the simple probability assessment approach our principal findings are 1 the gains from including non u s asset categories in the universe were remarkably large in some cases statistically significant especially for the highly risk averse strategies 2 the gains from removing the no leverage constraint were more substantial than they were in the absence of non u s securities and 3 there is strong evidence of market segmentation in that the optimal levels of investment in u s securities were mostly zero in the presence of the non u s asset categories