analyst forecasting errors additional evidence analyst forecasting errors are approximately as large as dreman and berry 1995 documented and an optimistic bias is evident for all years from 1985 through 1996 in contrast to their findings i show that analyst forecasting errors and bias have decreased over time moreover the optimistic bias in quarterly forecasts was absent for sp 2 firms with comparatively large amounts of market capitalization absolute value of earnings forecast and analyst following and 3 firms in certain industries

efficient resource allocation on the basis of priorities many institutions allocate resources by non market mechanisms based on priorities in this paper we introduce a model of resource allocation on the basis of priorities and address the following questions is it possible to allocate resources on the basis of any priority structure if yes when can we do this pareto efficiently without creating incentives for manipulation and consistently across different groups of agents and resource levels we adopt a basic indivisible objects model with a finite number of object types and a finite quota of goods of each type some interesting examples are the determination of access to education allocation of graduate houses offices or tasks agents are assumed to have strict preferences over object types and remaining unassigned an assignment is an allocation of the objects to the agents such that every agent receives at most one object a rule associates an assignment to each preference profile we formalize a priority structure to be a collection of strict priority rankings of individuals indexed by the object types where i a j would be read as i has higher priority for object a than j we assume that the priority structure is exogenously fixed and allow the preferences of the agents to vary a rule is said to violate a priority of i for a if there is a preference profile under which i envies j who is assigned a and publication information econometrica 70 6 november 2002 2489 2497 the copyright to this article is held by the econometric society http www econometricsociety org it may be downloaded printed and reproduced only for personal or classroom use absolutely no downloading or copying may be done for or on behalf of any for profit commercial firm or other commercial purpose without the explicit permission of the econometric society for this purpose contact julie p gordon executive director of the society at jpg northwestern edu i would like to thank faruk gul wolfgang pesendorfer the co editor the four anonymous referees and the participants of the micro theory lunch seminar in princeton university for their comments and suggestions

wage and price control policies in transition economies abstract this paper studies the structural impact of wage and price control policies in transition economies using a two sector three factor small open economy model it illustrates the results quantitatively via simulation exercises at the earlier stage of the transition when labor is immobile a strict control on the price of the nontradables and the wage rate minimizes the fall in employment and output also a more severe control on the price of the nontradables than on the wage rate alleviates the fall in the real wage at negligible costs in lost employment and output at the later stage of the transition when labor becomes mobile the liberalization of the price of the nontradables can proceed faster than that of the wage rate this policy combination increases employment and output and reduces the shortage for the nontradables but lowers the real wage

having your cake and eating it too the before and after tax efficiencies of an extended equity mandate this article shows that extended mandates are especially effective for investors subject to taxes not only is the portfolio more efficiently positioned from a before tax perspective but it also offers significant after tax benefits from both increased loss harvesting and tax arbitrage between tax rates on long and short positions

comparisons and combinations of long and long short strategies market neutral long short strategies get their returns from alphas and short rebates long strategies get their returns from alpha and the market differing return and risk sources complicate their comparison partly because of the strong market referenced focus of conventional performance analysis compelling theoretical advantages of active return per unit of active risk suggest that long short strategies are better able to deliver excess return than are conventional institutional long strategies long short strategies even with tiny positive alphas are seen to improve investors efficient frontiers when added to a traditional t bill long portfolio mix mostly because their risk sources are uncorrelated surprisingly the improvement occurs even if long short strategies are sharpe ratio inferior to long strategies these results provide theoretical support for including long short strategies in most investors mix of assets

the efficiency gains of long short investing long short strategies have generated controversy and institutional interest for more than 10 years we analyzed the efficiency gains of long short investing where we defined efficiency as the information ratio of the implemented strategy the optimal portfolio relative to the intrinsic information ratio of the alphas the efficiency advantage of long short investing arises from the loosening of the surprisingly important long only constraint long short and long only managers need to understand the impact of this significant constraint long short implementations offer the most improvement over long only implementations when the universe of assets is large asset volatility is low and the strategy has high active risk the long only constraint induces biases particularly toward small stocks limits the manager s ability to act on upside information by not allowing short positions that could finance long positions and reduces the efficiency of traditional high risk long only strategies relative t

leverage aversion and portfolio optimality portfolio volatility is the only source of risk in mean variance optimality but it fails to capture all the risks faced by leveraged portfolios these risks include the possibility of margin calls and forced liquidations at adverse prices and losses beyond the capital invested to recognize these risks the authors incorporated leverage aversion into the optimization process and examined the effects of volatility and leverage aversion on optimal long short portfolios

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

fundamentals of efficient factor investing corrected may 2017 combining long only constrained factor subportfolios is generally not a mean variance efficient way to capture expected factor returns for example a combination of four fully invested factor subportfolios low beta small size value and momentum captures less than half e g 40 of the potential improvement over the market portfolio s sharpe ratio in contrast a long only portfolio of individual securities using the same risk model and return forecasts captures most e g 80 of the potential improvement we adapt traditional portfolio theory to more recently popularized factor based investing and simulate optimal combinations of factor and security portfolios using the largest 1 000 common stocks in the us equity market from 1968 to 2015

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

the myth of the absolute return investor the notion of absolute return investing is spreading like wildfire many people believe that superior returns can be achieved by managers with strong views and little regard for benchmarks this article attempts to define absolute return investing and figure out whether it exists the conclusion is that all investment returns consist of a beta part representing the correlation of the active portfolio with one or more market benchmarks or normal portfolios and an active alpha part thus all investing is relative return investing in which active returns are earned relative to an appropriate benchmark or mix of benchmarks

in defense of portfolio optimization what if we can forecast author response we thank richard o michaud david n esch and robert o michaud for their interest in our paper in their letter they suggest that our results are inconsistent with the canonical literature beca

designing random allocation mechanisms theory and applications randomization is commonplace in everyday resource allocation we generalize the theory of randomized assignment to accommodate multi unit allocations and various real world constraints such as group specific quotas controlled choice in school choice and house allocation and scheduling and curriculum constraints in course allocation we develop new mechanisms that are ex ante efficient and fair in these environments and that incorporate certain non additive substitutable preferences we also develop a utility guarantee technique that limits ex post unfairness in random allocations supplementing the ex ante fairness promoted by randomization this can be applied to multi unit assignment problems and certain two sided matching problems jel c78 d82

comparing school choice mechanisms by interim and ex ante welfare recent work has highlighted welfare gains from the use of the boston mechanism over deferred acceptance da in school choice problems in particular finding that when cardinal utility is taken into account boston interim pareto dominates da in certain incomplete information environments with no school priorities we show that these previous interim results are not robust to the introduction of weak priorities however we partially restore the earlier results by showing that from an ex ante utility perspective the boston mechanism pareto dominates any strategyproof mechanism including da even allowing for arbitrary priority structures thus we suggest ex ante pareto dominance as a relevant criterion by which to compare school choice mechanisms this criterion may be of particular interest to school districts as they can be thought of as social planners whose goal is to maximize the overall ex ante welfare of the students

portfolio frontiers with restrictions to tracking error volatility and value at risk abstract asset managers are often given the task of restricting their activity by keeping both the value at risk var and the tracking error volatility tev under control however these constraints may be impossible to satisfy simultaneously because var is independent of the benchmark portfolio the management of these restrictions is likely to affect portfolio performance and produces a wide variety of scenarios in the risk return space the aim of this paper is to analyse various interactions between portfolio frontiers when risk managers impose joint restrictions upon tev and var specifically we provide analytical solutions for all the intersections and we propose simple numerical methods when such solutions are not available finally we introduce a new portfolio frontier

how variation in signal quality affects performance the information coefficient ic the correlation between forecasted and realized return is a popular measure of signal quality as shown in this article variation in ic is an important source of active risk and ic variation has an effect on optimal portfolio structure contrary to popular belief the ability to take short positions in equity portfolios does not necessarily lead to superior performance managers who can maintain a stable ic over time will benefit from short extensions but managers who have an unstable ic may see their performance deteriorate from increased short positions

the tax benefits of separating alpha from beta long only active investment strategies have an inherent flaw investors pay capital gains taxes on market related gains as well as on the alpha created by separating alpha and beta taxes can be r

on the optimality of long short strategies we consider the optimality of portfolios not subject to short selling constraints and derive conditions that a universe of securities must satisfy for an optimal active portfolio to be dollar neutr

illiquidity position limits and optimal investment for mutual funds we study the optimal trading strategy of mutual funds that face both position limits and differential illiquidity we provide explicit characterization of the optimal trading strategy and conduct an extensive analytical and numerical analysis of the optimal trading strategy we show that the optimal trading boundaries are increasing in both the lower and the upper position limits we find that position limits can affect current trading strategy even when they are not currently binding and other seemingly intuitive trading strategies can be costly we also examine the optimal choice of position limits

portfolio constraints and the fundamental law of active management active portfolio management is typically conducted within constraints that do not allow managers to fully exploit their ability to forecast returns constraints on short positions and turnover for example are fairly common and materially restrictive other constraints such as market capitalization and value growth neutrality with respect to the benchmark or economic sector constraints can further restrict an active portfolio s composition we derive ex ante and ex post correlation relationships that facilitate the performance analysis of constrained portfolios the ex ante relationship is a generalized version of a previously developed fundamental law of active management and provides an important strategic perspective on the potential for active management to add value the ex post correlation relationship represents a practical decomposition of performance into the success of the return prediction process and the noise associated with portfolio constraints we verify the accuracy of these relati

performance attribution and the fundamental law the reported study operationalized the fundamental law of active management in the context of a factor based performance attribution system the system incorporates factor payoffs in the linear regression framework that many portfolio managers and external reviewers use to judge what is being rewarded in the market the study indicates that parameters of the fundamental law can be used to approximate and interpret the results of the regression based performance attribution system the procedure is illustrated by the use of security holdings returns and factor exposure data for two portfolios benchmarked to the s p 500 index for april 1995 to march 2004

optimizing tracking error constrained portfolios active portfolios subject to tracking error te constraints are the typical setup for active managers tasked with outperforming a benchmark the risk and return relationship of such constrained po

resolving conflicting preferences in school choice the boston mechanism reconsidered the boston mechanism is among the most popular school choice pro cedures in use yet the mechanism has been criticized for its poor incentive and welfare performances which led the boston public schools to recently replace it with gale and shapley s deferred acceptance algorithm henceforth da the da elicits truthful revelation of ordinal preferences whereas the boston mechanism does not but the latter induces participants to reveal their cardinal preferences i e their relative preference intensities whereas the former does not we show that cardinal preferences matter more when families have similar ordinal preferences and schools have coarse priorities two common features of many school choice environ ments speci cally when students have the same ordinal preferences and schools have no priorities the boston mechanism pareto dominates the da in ex ante wel fare the boston mechanism may not harm but rather bene t participants who may not strategize well in the presence of school priorities the boston mechanism also tends to facilitate a greater access than the da to good schools by those lack ing priorities at those schools these results contrast with the standard view and cautions against a hasty rejection of the boston mechanism in favor of mechanisms such as the da

on the strategic behavior of large investors a mean variance portfolio approach abstract one key assumption of markowitz s model is that all traders act as price takers in this paper we extend this mean variance approach in a setting where large investors can move prices instead of having an individual optimization problem we find the investors nash equilibrium and redefine the efficient frontier in this new framework we also develop a simplified application of the general model with two assets and two investors to shed light on the potential strategic behavior of large and atomic investors our findings validate the claim that large investors enhance their portfolio performance in relation to perfect market conditions besides we show under which conditions atomic investors can benefit in relation to the standard setting even if they have not total influence on their eventual performance the two investors two assets setting allows us to quantify performance and do sensitivity analysis regarding investors market power risk tolerance and price elasticity of demand finally for a group of well known etfs we empirically show how price variations change depending on the volume traded we also explain how to set up and use our model with real market data