bayesian estimation and selection of nonlinear vector error correction models the case of the sugar ethanol oil nexus in brazil nonlinear adjustment toward long run price equilibrium relationships in the sugar ethanol oil nexus in brazil is examined we develop generalized bivariate error correction models that allow for cointegration between sugar ethanol and oil prices where dynamic adjustments are potentially nonlinear functions of the disequilibrium errors a range of models are estimated using bayesian monte carlo markov chain algorithms and compared using bayesian model selection methods the results suggest that the long run drivers of brazilian sugar prices are oil prices and that there are nonlinearities in the adjustment processes of sugar and ethanol prices to oil price but linear adjustment between ethanol and sugar prices

how does increased corn ethanol production affect us natural gas prices abstract in recent years there has been a push to increase biofuel production in the united states the biofuel of choice so far has been ethanol produced from corn the effects of increased corn ethanol production on the consumer prices of food and energy continue to be studied and debated this study examines in particular the effects of increased corn ethanol production on us natural gas prices a structural model of the natural gas market is developed and estimated using two stage least squares a baseline projection for the period 2007 2018 is determined and two scenarios are simulated in the first scenario current biofuel policies including eisa mandates tariffs and tax credits are removed in the second scenario we hold ethanol production to the level required only for largely obligatory additive use the results indicate that the increased level of corn ethanol production occurring as a result of the current us biofuel policies may lead to natural gas prices that are as much as 0 25 higher on average than if no biofuel policies were in place a similar comparison between the baseline and second scenario indicates natural gas prices could be as much as 0 5 higher on average for the same period

value at risk estimation with the optimal dynamic biofuel portfolio abstract in the past petroleum companies only paid attention to hedging the variation in the crude oil price and volatility however they have now expanded their analysis to encompass renewable sources such as corn and soybeans under the current low carbon biofuel obligations this paper employs garch 1 1 and arji models to estimate the one day ahead value at risk var of the optimal dynamic biofuel portfolio which consists of crude oil corn and soybeans the optimal blended standard is subject to the dual limitations of minimum production costs and the lowest biofuel using requirements our empirical findings confirm that the arji model is more suitable than the garch 1 1 model and further captures the discontinuous jump behavior from the in the sample data the results of out of sample forecasts also are represented that our models play important roles in var estimation and risk management for biofuel portfolio we therefore suggest that the petroleum companies should simultaneously pay attention to jump risk in hedging material costs in the prices of energy related crops

biodiesel as a motor fuel price stabilization mechanism abstract this article studies the capacity of biofuels to reduce motor fuel price fluctuations for this purpose we study dependence between crude oil and biodiesel blend prices in spain copula models are used for this purpose results suggest that the practice of blending biodiesel with diesel can protect consumers against extreme crude oil price increases

considering macroeconomic indicators in the food before fuel nexus abstract a structural vector autoregression svar model along with a direct acyclic graph is employed to decompose how supply demand structural shocks affect food and fuel markets the results support the hypothesis that fundamental market forces of demand and supply are the main drivers of food price volatility increased biofuel production may cause short run food price increases but not long run price shifts decentralized freely operating markets will mitigate the persistence of any price shocks and restore prices to their long run trends the main policy implications are that oil gasoline and ethanol market shocks do not spillover into grain prices which indicates no long run food before fuel issue in the short run grain prices can spike due to market shocks so programs designed to blunt these price spikes may be warranted

on the prevalence of trends in primary commodity prices abstract this paper applies new time series procedures to examine the prebisch singer hypothesis of a secular deterioration in relative primary commodity prices specifically we allow for up to two structural breaks in 24 price series covering the 1900 98 period for the majority of commodities it is shown that the trend is not well represented by a single downward slope but instead by a shifting trend that often changes sign over the sample period unlike some recent work that has also allowed for structural breaks these results provide much less support for the prebisch singer hypothesis

asymmetric contests with conditional investments rent seeking scenarios competitions for promotions and research and development r d races are examples of competitions in which participants expend resources regardless of whether they win or lose although similar in their all pay feature such competitions often differ in important dimensions these include the type of technologies employed in competition the type of asymmetries among competitors the degree to which expenditures are sunk and the number of prizes consider lobbying settings in which firms expend resources in order to influence a policymaker if expenditures take the form of monetary outlays and all firms have the same cost of capital then it is reasonable to think of firms marginal cost of influence as linear but if a firm has a reputational advantage and high costs of capital its lobbying technology may be more reasonably thought of as having convex costs relatively low marginal costs up to a moderate level of influence due to the reputational advantage and relatively high marginal costs at higher levels of influence due to the high costs of capital similarly the lobbying technology of a firm that is relatively unknown and has low costs of capital may be characterized by concave costs lobbying restrictions geographic location or preferential treatment by the policymaker further impact firms lobbying technologies inducing additional nonlinearities and asymmetries among firms in some lobbying settings firms also commit to expenditures conditional on a favorable outcome for example a firm may commit to building factories and creating new jobs if it is granted one of a limited number of manufacturing licenses thus the specification of firms lobbying technologies the type of asymmetries among firms the combination of unconditional and conditional investments and the number of eventual winners may change according to the lobbying setting studied the same is true for other competitions with an all pay feature in a competition for promotions workers often differ in their abilities experience and social skills more than one prize

price cycles and asymmetric price transmission in the u s pork market economists have proposed several plausible explanations for observed price transmission asymmetries in commodity markets unfortunately the econometric methods commonly used in such studies cannot empirically distinguish pricing behavior under the competing theories we argue that the theories may be classified by firm responses to high and low frequency price cycles and use engle s band spectrum regression to test the symmetry of high and low frequency cycles in weekly pork prices the findings indicate that changes in wholesale prices are asymmetrically transmitted to retail prices in relatively low frequency cycles which does not support search costs and other high frequency explanations conversely wholesale pork prices asymmetrically adjust to changes in farm prices at all frequencies copyright 2001 oxford university press

dissipation of contestable rents by small numbers of contenders the theory of rent seeking with its origins in the observations of gordon tullock 1967 or to use jagdish bhagwati s 1982 proposed term the theory of directly unproductive profit seeking activities is concerned with the potentially adverse effects on resource allocation of incentives to cap ture and defend artificially contrived rents and transfers the scope for so cial loss proposed by the theory derives from the relation between the value of a contestable prize and the value of the resources attracted into the con test to determine the beneficiary of the prize underlying this social loss is a specification of how rational behavior by optimizing agents links the value of the prize sought to the resources expended it has been traditional to assume competitive behavior in describing the activities of lobbying and influence seeking then if some further condi tions are satisfied l the total value of the resources expended precisely equals the value of the prize sought so dissipation is complete 2 conse quently the social cost associated with contestability of a rent can be in ferred from the value of the rent itself and the detailed and hard to come by information on individual outlays made in the course of the contest be comes unnecessary by basing their analyses on competitive dissipation contributors to the rent seeking literature see the review by robert tollison 1982 have been able to presume that the observed value of a contested rent is an exact measure of the associated social cost of monopoly power or regu lation similarly in the trade theoretic literature where the rights contested are to quota premia or revenues from trade taxes krueger 1974 bhagwati

a lagrange multiplier test for causality in variance we adapt the lagrange multiplier lm principle to test for noncausality in variance of financial returns the new test is compared with a portmanteau statistic cheung y w ng l k 1996 a causality in variance test and its application to financial market prices journal of econometrics 72 33 48 a monte carlo study reveals superior power of the lm test

favoritism in asymmetric contests head starts and handicaps abstract i examine a contest with identity dependent rules in which contestants are privately informed and ex ante heterogeneous a contestant may suffer from a handicap or benefit from a head start the former reduces the contestant s score by a fixed percentage the latter is an additive bonus although total effort increases if the weak contestant is favored with a head start the optimal use of handicaps is not as clear cut depending on the nature of the asymmetry it may or may not be optimal to handicap the strong contestant moreover it is generally optimal to combine the two instruments for instance when contestants are sufficiently heterogeneous the weak contestant should be given both a head start and a handicap it may also be possible to induce higher effort and at the same time make both contestants better off ex ante

biofuel related price transmission literature a review abstract in this article an extensive review of the rapidly growing biofuel related time series literature is carried out the data used the modeling techniques and the main findings of this literature are discussed providing a review of this flourishing research area is relevant as a guidepost for future research this literature concludes that energy prices drive long run agricultural price levels and that instability in energy markets is transferred to food markets

the interaction between food prices and oil prices this paper provides a statistical methodology to estimate the impact of oil price uncertainty on food prices in doing so it examines the joint impact of oil price and food price uncertainties and their correlation on the food price also the theoretical model was applied to the oil based trinidad and tobago and the empirical results confirm the theoretical predictions the empirical results indicate that a higher oil price increases food price also a higher oil price volatility yields a higher food price moreover an increase in the oil supply reduces the food price

price formation in the german biodiesel supply chain a markov switching vector error correction modeling approach changing linkages between agricultural and energy markets have attracted considerable attention in research and policy discussions during recent years as one of the largest biofuel markets worldwide the german biodiesel market is of particular interest it has grown rapidly since the beginning of the new millennium with this growth being driven mainly by political interventions vertical price transmission channels along the biodiesel supply chain are analyzed in this study we examine the relationship between diesel and biodiesel prices and between rapeseed oil soy oil and biodiesel prices between 2002 and 2008 due to pronounced changes in market conditions and the policy framework a regime dependent markov switching vector error correction model is used the regimes are characterized by markedly different price adjustment behaviors before 2005 and from late 2007 onward a regime characterized by the strong orientation of biodiesel prices toward diesel prices dominates between 2005 and 2007 biodiesel and rapeseed oil prices are mutually interdependent frequent switches between the regimes of the price dynamics during this period indicate a high extent of uncertainty and instability in the market

about time daylight saving time transition and individual well being daylight saving time is controversial due to its alleged negative impact on individual well being using panel data from germany we find evidence that the transition to summer time has negative influence on general life satisfaction and mood which is stronger for those in full time employment

poker player behavior after big wins and big losses we find that experienced poker players typically change their style of play after winning or losing a big pot most notably playing less cautiously after a big loss evidently hoping for lucky cards that will erase their loss this finding is consistent with kahneman and tversky s kahneman d a tversky 1979 prospect theory an analysis of decision under risk econometrica47 2 263 292 break even hypothesis and suggests that when investors incur a large loss it might be time to take a vacation or be monitored closely

losing sleep at the market the daylight saving anomaly reply motivated by the recent flurry of activity in sleep research this paper explores the connection between sleep disruptions following spring and fall clock shifts associated with daylight savings time and equity returns it is shown that the weekend effect in the form of the lower than expected friday to monday returns is particularly pronounced for the two weekends involving daylight savings clock changes this abstract was borrowed from another version of this item

volatility spillovers between food and energy markets a semiparametric approach previous literature on volatility links between food and energy prices is scarce and mainly based on parametric approaches this article examines these links by using a semiparametric garch model recently proposed by long et al 2011 which is essentially a nonparametric correction of the parametric conditional covariance function the analysis focuses on price links between crude oil ethanol and sugar prices in brazil results suggest strong volatility links between the prices studied parametric approximations of the conditional covariance matrix may lead to misleading results that can be improved upon by using nonparametric techniques

autoregressive conditional heteroscedasticity in commodity spot prices muth s 1961 rational expectations model of commodity markets implies that inventory carryover creates arch processes in prices the model also indicates that the expected price variance is an explanatory variable in price regressions hypotheses were tested on price data of twenty commodities using a variation of engle et al 1987 arch m technique an arch process was found in storable and not in non storable commodity data as expected however changes in expected price variance have no significant impact on price copyright 2001 john wiley sons ltd

food versus fuel what do prices tell us abstract sorting out the impacts of biofuels on global agricultural commodity prices is impossible without turning to data and distinguishing between the short run versus the long run impacts using time series prices on fuels and agricultural commodities the aim is to investigate the long run cointegration of these prices simultaneously with their multivariate short run interactions results indicate no direct long run price relations between fuel and agricultural commodity prices and limited if any direct short run relationships in terms of short run price movements sugar prices are influencing all the other agricultural commodity prices except rice with sugar the number one world input for ethanol results indicate increased ethanol production is potentially influencing short run agricultural commodity prices overall results support the effect of agricultural commodity prices as market signals which restore commodity markets to their equilibria after a demand or supply event shock

world oil and agricultural commodity prices evidence from nonlinear causality abstract the increasing co movements between the world oil and agricultural commodity prices have renewed interest in determining price transmission from oil prices to those of agricultural commodities this study extends the literature on the oil agricultural commodity prices nexus which particularly concentrates on nonlinear causal relationships between the world oil and three key agricultural commodity prices corn soybeans and wheat to this end the linear causality approach of toda yamamoto and the nonparametric causality method of diks panchenko are applied to the weekly data spanning from 1994 to 2010 the linear causality analysis indicates that the oil prices and the agricultural commodity prices do not influence each other which supports evidence on the neutrality hypothesis in contrast the nonlinear causality analysis shows that i there are nonlinear feedbacks between the oil and the agricultural prices and ii there is a persistent unidirectional nonlinear causality running from the oil prices to the corn and to the soybeans prices the findings from the nonlinear causality analysis therefore provide clues for better understanding the recent dynamics of the agricultural commodity prices and some policy implications for policy makers farmers and global investors this study also suggests the directions for future studies

nonlinearities in the u s corn ethanol oil gasoline price system we use a smooth transition vector error correction model to assess price relationships within the u s ethanol industry monthly ethanol corn oil and gasoline prices from 1990 to 2008 are used in the analysis results indicate the existence of long run relationships among the prices analyzed strong links between energy and food prices are identified

does daylight saving time save energy evidence from a natural experiment in indiana abstract we take advantage of a natural experiment in the state of indiana to estimate the effect of daylight saving time dst on residential electricity consumption our main finding is that contrary to the policy s intent dst increases electricity demand the findings are consistent with simulation results that identify a trade off between reducing demand for lighting and increasing demand for heating and cooling we estimate a cost to indiana households of 9 million per year in increased electricity bills we also estimate social costs of increased pollution emissions between 1 7 to 5 5 million per year

asymmetry in retail gasoline and crude oil price movements in the united states an application of hidden cointegration technique abstract there is a common belief that gasoline prices respond more quickly to crude oil price increases than decreases some economists and politicians believe that asymmetry in oil and gasoline price movements is the outcome of a non competitive gasoline market requiring that governments take policy action to address unfair pricing there is no consensus as to the existence or nature of the asymmetric relationship between prices of gasoline and crude oil much of this literature specifies asymmetry in the speed of adjustment and short run adjustment coefficients in contrast granger and yoon s granger c w and yoon g hidden cointegration university of california san diego department of economics working paper 2002 crouching error correction model cecm identifies asymmetry of the cointegrating vectors between components cumulative positive and negative changes of the series applying the cecm to retail gasoline and crude oil prices for the u s we find that there is only evidence of cointegration between positive components of crude oil prices and negative components of gasoline prices in contrast to the literature which attributes asymmetric price movements to market power of refiners these findings suggest that gasoline prices in the long run are more influenced by the technological changes on the demand side than crude oil price movements on the supply side

dynamic impacts of high oil prices on the bioethanol and feedstock markets this study investigates the impacts of high international oil prices on the bioethanol and corn markets in the us between 2007 and 2008 the prices of major grain crops had increased sharply reflecting the rise in international oil prices these dual price shocks had caused substantial harm to the global economy employing a structural vector auto regression model svar we analyze how increases in international oil prices could impact the prices of and demand for corn which is used as a major bioethanol feedstock in the us the results indicate that an increase in the oil price would increase bioethanol demand for corn and corn prices in the short run and that corn prices would stabilize in the long run as corn exports and feedstock demand for corn decline consequently policies supporting biofuels should encourage the use of bioethanol co products for feed and the development of marginal land to mitigate increases in the feedstock price

how market efficiency and the theory of storage link corn and ethanol markets this article uses the theories of market efficiency and supply of storage to develop a conceptual link between the corn and ethanol markets and explores statistical evidence for the link we propose that a long run no profit condition is established in distant futures markets for ethanol corn and natural gas and then use the theory of storage to define an inter temporal equilibrium among these prices the relationship shows that under certain conditions future price expectations will influence nearby futures prices and that a short term relationship between input and output prices will exist we demonstrate validity of the theory using a structural price model and then by means of time series techniques

all pay contests this paper studies a class of games all pay contests which capture general asymmetries and sunk investments inherent in scenarios such as lobbying competition for market power labor market tournaments and r d races players compete for one of several identical prizes by choosing a score conditional on winning or losing it is weakly better to do so with a lower score this formulation allows for differing production technologies costs of capital prior investments attitudes toward risk and conditional and unconditional investments among others i provide a closed form formula for players equilibrium payoffs and analyze player participation a special case of contests is multiprize complete information all pay auctions

assessing the effect of oil price on world food prices application of principal component analysis the objective of this paper is to investigate the co movement of food prices and the macroeconomic index especially the oil price by principal component analysis to further understand the influence of the macroeconomic index on food prices we examined the food prices of seven major products eggs meat milk oilseeds rice sugar and wheat the macroeconomic variables studied were crude oil prices consumer price indexes food production indexes and gdp around the world between 1961 and 2005 we use the scree test and the proportion of variance method for determining the optimal number of common factors the correlation coefficient between the extracted principal component and the macroeconomic index varies between 0 87 for the world gdp and 0 36 for the consumer price index we find the food production index has the greatest influence on the macroeconomic index and that the oil price index has an influence on the food production index consequently crude oil prices have an indirect effect on food prices

are biofuels the culprit opec food and fuel the food commodity price boom of 2003 2008 was the most notable in the past several decades having a substantial impact on global economic activity it affected developing nations by impacting real output the balance of payments government budgetary positions and most important the well being of the very poor high commodity prices also affected developed countries by transmitting business cycle disturbances and creating inflationary pressures several recent studies tried to identify and quantify the factors that caused the food commodity price boom of 2003 2008 see for instance isabel vansteenkiste 2009 these studies suggest that one key factor is growth in demand which since the 1980s has outpaced growth in supply other studies argued that biofuel is the culprit since it increases demand for staple crops see for instance donald mitchell 2008 all these studies however assumed competitive markets and did not consider the impact of biofuel on energy costs to farmers moreover they ignored the organization of petroleum exporting countries opec these studies leave us perplexed regarding the true impact of biofuel on food commodity prices was it or was it not an important contributor to the recent food commodity boom we believe that to answer this question the interactions between energy and food must be modeled and opec introduced and the impact of biofuels compared with other factors that are argued by the literature to be important this paper aims to analyze the multiple contributions of energy and biofuels to the increase are biofuels the culprit opec food and fuel

oil price agricultural commodity prices and the dollar a panel cointegration and causality analysis abstract this study examines the dynamic relationship between world oil prices and twenty four world agricultural commodity prices accounting for changes in the relative strength of us dollar in a panel setting we employ panel cointegration and granger causality methods for a panel of twenty four agricultural products based on monthly prices ranging from january 1980 to february 2010 the empirical results provide strong evidence on the impact of world oil price changes on agricultural commodity prices contrary to the findings of many studies in the literature that report neutrality of agricultural prices to oil price changes we find strong support for the role of world oil prices on prices of several agricultural commodities the positive impact of a weak dollar on agricultural prices is also confirmed

gambling in contests with heterogeneous loss constraints i study the impact of asymmetric loss constraints on risk taking behavior in the contest model of seel and strack 2013 i derive the unique nash equilibrium outcome the equilibrium payoffs and comparative statics about the bankruptcy risk

assessing the impact of us ethanol on fossil fuel markets a structural var approach abstract despite the growing importance of biofuels the effect of biofuels on fossil fuel markets is not fully understood we develop a joint structural vector auto regression var model of the global crude oil us gasoline and us ethanol markets to examine whether the us ethanol market has had any impact on global oil markets the structural var approach provides a unique method for decomposing price and quantity data into demand and supply shocks allowing us to estimate the distinct dynamic effects of ethanol demand and supply shocks on the real prices of crude oil and us gasoline ethanol demand in the us is driven mainly by government support in the form of tax credits and blending mandates shocks to ethanol demand therefore reflect changes in policy more than any other factor in contrast ethanol supply shocks are driven by changes in feedstock prices a principle finding is that a policy driven ethanol demand expansion causes a statistically significant decline in real crude oil prices while an ethanol supply expansion does not have a statistically significant impact on real oil prices this suggests that even though us ethanol market is small the influence of us biofuels policy on the crude oil market is pervasive we also show that ethanol demand shocks are more important than ethanol supply shocks in explaining the fluctuation of real prices of crude oil and us gasoline

investment in the absence of property rights the role of incumbency advantages in many situations the individuals who can generate some output must enter a contest for appropriating this output this paper analyses the investment incentives of such agents and the role of incumbency advantages in the contest depending on the advantages an increase in the productivity of the investment can decrease or increase the amount of investment the results are applied to autocrats investment behavior and job specific investment in organizations

volatility spillover between oil and agricultural commodity markets abstract this study examines volatility transmission between oil and selected agricultural commodity prices wheat corn soybeans and sugar we apply the newly developed causality in variance test and impulse response functions to daily data from 01 january 1986 to 21 march 2011 in order to identify the impact of the food price crisis the data are divided into two sub periods the pre crisis period 01 january 1986 to 31 december 2005 and the post crisis period 01 january 2006 21 march 2011 the variance causality test shows that while there is no risk transmission between oil and agricultural commodity markets in the pre crisis period oil market volatility spills on the agricultural markets with the exception of sugar in the post crisis period the impulse response analysis also indicates that a shock to oil price volatility is transmitted to agricultural markets only in the post crisis period this paper thereby shows that the dynamics of volatility transmission changes significantly following the food price crisis after the crisis risk transmission emerges as another dimension of the dynamic interrelationships between energy and agricultural markets

a model of casino gambling we show that prospect theory offers a rich theory of casino gambling one that captures several features of actual gambling behavior first we demonstrate that for a wide range of preference parameter values a prospect theory agent would be willing to gamble in a casino even if the casino offers only bets with no skewness and with zero or negative expected value second we show that the probability weighting embedded in prospect theory leads to a plausible time inconsistency at the moment he enters a casino the agent plans to follow one particular gambling strategy but after he starts playing he wants to switch to a different strategy the model therefore predicts heterogeneity in gambling behavior how a gambler behaves depends on whether he is aware of the time inconsistency and if he is aware of it on whether he can commit in advance to his initial plan of action this paper was accepted by brad barber teck ho and terrance odean special issue editors

world oil prices and agricultural commodity prices evidence from an emerging market abstract oil prices are thought to have direct effect on agricultural prices followed by an indirect effect through the exchange rate this paper examines the short and long run interdependence between world oil prices lira dollar exchange rate and individual agricultural commodity prices wheat maize cotton soybeans and sunflower in turkey to this end the toda yamamoto causality approach and generalized impulse response analysis for identification of the long and short run interrelationships are applied to the monthly data spanning from january 1994 to march 2010 the impulse response analysis suggests the turkish agricultural prices do not significantly react to oil price and exchange rate shocks in the short run the long run causality analysis reveals that the changes in oil prices and appreciation depreciation of the turkish lira are not transmitted to agricultural commodity prices in turkey hence our results support neutrality of agricultural commodity markets in turkey to both direct and indirect effects of oil price changes

commodity prices and growth in africa a frican economies export primary commodities and most export little else policymakers as well as economists and historians of african economic development have seen these exports as both a hope and a curse the following parable tells the story once upon a time a servant of the ruler discovered a miraculous plant which grew readily in that country and whose seeds could be woven into fine cloth so desirable was this fabric that it became prized all over the world and fetched a high price after two score years the plant accounted for most of the country s trade with the world the ruler ordered the peasants to grow the plant paid them only a fraction of its price and he and his nobles became fabulously wealthy because the ruler wished to be remembered as a great ruler and as the father of his country he used his wealth to build a great army and brought machines from foreign countries to make the fine goods that previously could only be obtained from foreign merchants but the machines often broke down and the goods that they made were of poor quality and after the ruler died they were left to rust under the ruler s successor there was a war in a foreign land where the plant also grew so that there was a great shortage and its price increased threefold in only three seasons the new ruler spent his newfound riches on fantastic extravagance while immense sums were expended on public works after the manner of the east and on productive works carried out in the wrong way or too soon not even the threefold increase in prices could support these expenditures and the country soon found itself deeply in debt when the war ended and the price fell the country could no longer pay the interest on its debt or borrow more money even after it had sold its only useful public work to a foreign power so that power sent a mission to the country the publication of whose report from which the above

gambling in contests this paper presents a strategic model of risk taking behavior in contests formally we analyze an n player winner take all contest in which each player decides when to stop a privately observed brownian motion with drift a player whose process reaches zero has to stop the player with the highest stopping point wins unlike the explicit cost for a higher stopping time in a war of attrition here higher stopping times are riskier because players can go bankrupt we derive a closed form solution of a nash equilibrium outcome in equilibrium highest expected losses occur at an intermediate negative value of the drift

modeling asymmetric comovements of asset returns existing time varying covariance models usually impose strong restrictions on how past shocks affect the forecasted covariance matrix in this article we compare the restrictions imposed by the four most popular multivariate garch models and introduce a set of robust conditional moment tests to detect misspecification we demonstrate that the choice of a multivariate volatility model can lead to substantially different conclusions in any application that involves forecasting dynamic covariance matrices like estimating the optimal hedge ratio or deriving the risk minimizing portfolio we therefore introduce a general model which nests these four models and their natural asymmetric extensions the new model is applied to study the dynamic relation between large and small firm returns article published by oxford university press on behalf of the society for financial studies in its journal the review of financial studies