heavy tails and copulas limits of diversification revisited we show that diversification does not reduce value at risk for a large class of dependent heavy tailed risks the class is characterized by power law marginals with tail exponent no greater than one and by a general dependence structure which includes some of the most commonly used copulas

the behavior of extreme values in germany s stock index futures an application to intradaily margin setting recent defaults and large financial losses attributed to derivative security investing point to an area of finance not often researched i e the probabilities of observing extreme occurrences this paper examines this behavior for german stock index futures fdax contracts its empirical results indicate that large fdax intradaily price changes follow a frechet extreme value distribution and the extreme value distribution probabilities may be confidently used to help set intradaily margin levels

breaks and outliers when modelling the volatility of the u s stock market this study analyses volatility persistence of the u s stock market after taking into account the role of breaks and outliers by employing a wavelet based algorithm it identifies several outliers which are comfortably associated with major events such as the black monday and the asian crisis there is also evidence of clustering of breaks and a substantial variation in the properties of the identified segments

financial crashes as endogenous jumps estimation testing and forecasting abstract this paper provides an econometric approach for forecasting financial crashes based on diffusion processes with time varying parameters that are driven by market fundamentals under a polynomial drift function one obtains a cusp stochastic process that entails a generalized exponential stationary distribution this class of densities is quite convenient as it allows for skewness different tail shapes and even multimodality which corresponds to multiple equilibria movements from one equilibrium to another due to changes in the market fundamentals then relates to crashes methods for fitting and evaluating this sort of diffusion processes are proposed to enable the estimation and forecast of crash events finally an empirical assessment is carried out by tracking the likelihood of a crash during the swedish twin crises in the early 1990s

the simple economics of bank fragility banks are linked through the interbank deposit mar ket participations like syndicated loans and deposit interest rate risk the similarity in exposures carries the potential for systemic breakdowns this potential is either weak or strong depending on whether the linkages remain or vanish asymptotically it is shown that the linearity of the bank portfolios in the exposures in combi nation with a condition on the tails of the marginal distributions of these exposures determines whether the potential for systemic risk is weak or strong we show that if the exposures have marginal normal distributions the potential for systemic risk is weak while if e g the student distributions apply the potential is strong

contagion risk in the australian banking and property sectors abstract the australian banking system emerged from the global crisis virtually unhurt with most banks still profitable adequately capitalized and with aa credit ratings are there any risks or vulnerabilities in this success story this paper analyzes australia s systemic banking risk and attempts to determine if this risk increased with the recent global crisis and whether this risk is related to the downturn experienced in the real estate market we use extreme value theory to measure banks and property firms univariate value at risk as well as multivariate intra sector and inter sector contagion risks of the 13 sectors analyzed we find that the property sector exhibits the highest level of extremal dependence with the banking sector the credit crisis significantly increased the probability of a bank or property firm crashing moreover contagion risks significantly increased not only within the banking and property sectors but also between those sectors

tail risk and systemic risk of us and eurozone financial institutions in the wake of the global financial crisis we evaluate multiple market based measures for us and eurozone individual bank tail risk and bank systemic risk we apply statistical extreme value analysis to the tails of bank equity capital losses to estimate the likelihood of individual institutions financial distress as well as individual banks exposure to each other spillover risk and to global shocks extreme systematic risk the estimation procedure presupposes that bank equity returns are heavy tailed and tail dependent as identifying assumption using both us and eurozone banks allows one to make a cross atlantic comparison of tail risks and systemic stability we also assess to what extent magnitudes of tail risk and systemic risk have been altered by the global financial crisis the results suggest that both tail risk and systemic risk in the us are higher than in the eurozone regardless of the considered sample period

the limits of diversification when losses may be large abstract recent results in value at risk analysis show that for extremely heavy tailed risks with unbounded distribution support diversification may increase value at risk and that generally it is difficult to construct an appropriate risk measure for such distributions we further analyze the limitations of diversification for heavy tailed risks we provide additional insight in two ways first we show that similar non diversification results are valid for a large class of risks with bounded support as long as the risks are concentrated on a sufficiently large interval the required length of the support depends on the number of risks available and on the degree of heavy tailedness second we relate the value at risk approach to more general risk frameworks we argue that in markets for risky assets where the number of assets is limited compared with the bounded distribution support of the risks unbounded heavy tailed risks may provide a reasonable approximation we suggest that this type of analysis may have a role in explaining various types of market failures in markets for assets with possibly large negative outcomes

measuring systemic importance of financial institutions an extreme value theory approach abstract this paper proposes a set of market based measures on the systemic importance of a financial institution or a group of financial institutions each designed to capture different aspects of systemic importance of financial institutions multivariate extreme value theory approach is used to estimate these measures using six big canadian banks as the proxy for canadian banking sector we apply these measures to identify systemically important banks in canadian banking sector and major risk contributors from international financial institutions to canadian banking sector the empirical evidence reveals that i the top three banks rbc financial group td bank financial group and scotiabank are more systemically important than other banks while we also find that the size of a financial institution should not be considered as a proxy of systemic importance ii compared to the european and asian banks the crashes of the u s banks on average are the most damaging to canadian banking sector while the risk contribution to the canadian banking sector from asian banks is quite lower than that from banks in the u s and euro area iii the risk contribution to canadian banking sector exhibits home bias that is cross country risk contribution tends to be smaller than domestic risk contribution

short sales in log robust portfolio management abstract this paper extends the log robust portfolio management approach to the case with short sales i e the case where the manager can sell shares he does not yet own we model the continuously compounded rates of return which have been established in the literature as the true drivers of uncertainty as uncertain parameters belonging to polyhedral uncertainty sets and maximize the worst case portfolio wealth over that set in a one period setting the degree of the manager s aversion to ambiguity is incorporated through a single intuitive parameter which determines the size of the uncertainty set the presence of short selling requires the development of problem specific techniques because the optimization problem is not convex in the case where assets are independent we show that the robust optimization problem can be solved exactly as a series of linear programming problems as a result the approach remains tractable for large numbers of assets we also provide insights into the structure of the optimal solution in the case of correlated assets we develop and test a heuristic where correlation is maintained only between assets invested in in computational experiments the proposed approach exhibits superior performance to that of the traditional robust approach

the effect of asset and ownership structure on political risk some evidence from mitterrand s election in france abstract previous research suggests that political risk varies considerably from firm to firm yet few empirical tests of the cross sectional variation in political risk exist french assets were massively revalued the day after mitterrand was elected in 1981 providing a unique opportunity to test for the effect of firm specific factors on political risk although foreign ownership tends to increase political risk other factors can reduce it a simple model of political behavior is presented in which politicians value among other things economic growth a foreign firm with significant future growth options is likely to experience less political risk than other foreign firms and under certain circumstances less risk than even other domestic firms tests of these hypotheses are conducted using data from the french and u s capital markets the results are generally consistent with the hypotheses

differences between foreign exchange rate regimes the view from the tails abstract in the literature on the empirical unconditional distribution of foreign exchange rate returns there is indication that the type of distribution function is related to the form of exchange rate regime the analysis has been hampered by the nonnestedness of alternative distribution models the paper investigates the issue by means of extremal analysis which allows for a unified treatment in particular we try to sort out whether apparent distributional differences are due to differences in techniques or in regimes jel f31 f33

an extreme value approach to estimating volatility and value at risk this article determines the type of asymptotic distribution for the extreme changes in u s treasury yields the thin tailed gumbel and exponential distributions are strongly rejected against the fat tailed frechet and pareto distributions the empirical results indicate that the volatility of maximal and minimal changes in interest rates declines as time to maturity rises yielding a downward sloping volatility curve for the extremes the article proposes an extreme value approach to estimating value at risk and shows that the statistical theory of extremes provides a more accurate approach for risk management and value at risk var calculations than the standard models

overnight borrowing interest rates and extreme value theory we examine the dynamics of extreme values of overnight borrowing rates in an inter bank money market before a financial crisis during which overnight borrowing rates rocketed up to simple annual 4000 percent it is shown that the generalized pareto distribution fits well to the extreme values of the interest rate distribution we also provide predictions of extreme overnight borrowing rates before the crisis the examination of tails extreme values provides answers to such issues as what are the extreme movements expected in financial markets have we already seen the largest moves is there a possibility for even larger movements and are there theoretical processes that can model the type of fat tails in the observed data the answers to such questions are essential for proper management of financial exposures and laying ground for regulations

an extreme value analysis of the last century crises across industries in the u s economy the two large scale crises that hit the world economy in the last century i e the great depression and the great recession have similar outbreak and recovery patterns with respect to several macroeconomic variables in particular the largest depressions are likely to be accompanied by stock market crashes this study investigates the behavior of the u s stock market before during and after deep downturns focusing particularly on the tails of the return distribution we develop two automatic procedures to identify multiple change points in the tail of financial time series as well as in the co crash and co boom probabilities of different markets we then apply our methodology to twelve time series representative of the sectors of the u s economy we find that regime shifts in the lower tail of the distribution tend to co occur before deep downturns our results contribute to a better understanding of the origin and systemic nature of large scale events to make policy interventions more timely and effective

fixed versus flexible exchange rates and measurement of exchange rate instability comment this paper comments on brodsky 1984 in which he refers to my november 1981 article the paper reiterates the point that the standard deviation cannot be used to draw statistical inferences when the underlying distribution is non normal stable paretian in such a case both the scale and characteristic exponent have to be considered

measuring tail thickness to estimate the stable index α a critique a generalized pareto or simple pareto tail index estimate above 2 has frequently been cited as evidence against infinite variance stable distributions it is demonstrated that this inference is invalid tail index estimates greater than 2 are to be expected for stable distributions with as low as 1 65 the nonregular distribution of the likelihood ratio statistic for a null of normality and an alternative of symmetric stability is tabulated by monte carlo methods and appropriately adjusted for sampling error in repeated tests real stock returns yield a stable of 1 845 and reject iid normality at the 996 level

emerging markets and heavy tails abstract emerging countries are held to be subject to more frequent and more pronounced external and internal shocks than their developed counter parts this suggests that key variables pertaining to their markets including their exchange rates will be marked by greater likelihood of extreme observations and large fluctuations we focus on the hypothesis that compared to developed country exchange rates emerging country exchange rates will be more pronouncedly heavy tailed we find support for the hypothesis using recently proposed robust tail index estimation methods which in particular perform well under heavy tailed dependent garch processes that are often used for modeling exchange rates according to the estimation results reported in the paper variances may be infinite for several emerging country exchange rates tail index values p 2 6 2 8 appear to be at the dividing boundary between the two sets of countries while the moments of order p 2 6 2 8 are finite for most of the developed country exchange rates they may be or are infinite for most of the emerging country exchange rates we also study the impact of the on going financial and economic crisis and find that heavy tailedness properties of most exchange rates did not change significantly with the onset of the crisis at the same time some foreign exchange markets have experienced structural changes in their heavy tailedness properties during the crisis

structural change tests in tail behaviour and the asian crisis this paper explores tests of the hypothesis that the tail thickness of a distribution is constant over time using hill s conditional maximum likelihood estimator for the tail index of a distribution tests of tail shape constancy are constructed that allow for an unknown breakpoint the recursive test is shown to be inconsistent in one direction and only a one sided test is recommended specifically the test can be used when the alternative hypothesis is that the tail index decreases over time a rolling and sequential version of the test is consistent in both directions the methods are illustrated on recent stock price data for thailand malaysia and indonesia the period covers the recent asian financial crisis and enables us to assess whether breakpoints in domestic asset return distributions are related to known changes in institutional arrangements in the foreign currency markets of these countries

tail risk dynamics in stock returns links to the macroeconomy and global markets connectedness we propose a new time varying peaks over threshold model to study tail risk dynamics in equity markets the laws of motion for the parameters are defined through the score based approach we apply the model to daily returns from u s size sorted decile stock portfolios and show that large firms tail risk increases during recessions more than small firms tail risk our results are consistent with the granular hypothesis of aggregate fluctuations and we quantify the impact of large firms tail risk shocks on the economy a measure of tail connectedness is proposed evidence from international equity markets shows that tail connectedness increases during periods of turmoil this paper was accepted by lauren cohen finance

does it pay to change your company s name a stock market perspective a company s name is commonly considered to be an integral part of its image just like the quality of its products or the quality of its technical services changing a company s name is a major policy decision contemplated by many firms and actually implemented by some each year this paper attempts to examine albeit indirectly whether a name change can improve the profit performance of a firm and what type of firm is more likely to succeed in doing so we use the event study methodology developed in finance to examine the above questions with respect to 58 corporations that changed their names in 1981 1985 our findings are that for most of the firms name changes are associated with improved performance and that the greatest improvement tends to occur in firms that produce industrial goods and whose performance prior to the change was relatively poor evidence that industrial good producers are also heavy users of corporate advertising lends further credence to this finding our findings do not support however the contention that the new name per se will enhance demand for the firm s products rather it seems that the act of a name change serves as a signal that other measures to improve performance such as changes in product offerings and organizational changes will be seriously and successfully undertaken the rationale behind why such a signal is sent and why it is believed is discussed

time reversibility tests of volume volatility dynamics for stock returns abstract non parametric tests based on the concept of time reversibility in statistical mechanics are applied to assess the dynamic implications of the mixture of distributions hypothesis mdh the tests show that shocks to volume and volatility are dynamically asymmetric thus rejecting the one factor mdh

the tail index of exchange rate returns in the literature on the empirical distribution of foreign exchange rates there is now consensus that exchange rate yields are fat tailed three problems however persist 1 which class of distribution functions is most appropriate 2 are the parameters of the distribution invariant over subperiods 3 what are the effects of aggregation over time on the distribution in this paper we employ extreme value theory to shed new light on these questions we apply the theoretical results to ems data

estimating the marginal law of a time series with applications to heavy tailed distributions this article addresses estimating parametric marginal densities of stationary time series in the absence of precise information on the dynamics of the underlying process we propose using an estimator obtained by maximization of the quasi marginal likelihood which is a likelihood written as if the observations were independent we study the effect of the neglected dynamics on the asymptotic behavior of this estimator the consistency and asymptotic normality of the estimator are established under mild assumptions on the dependence structure applications of the asymptotic results to the estimation of stable generalized extreme value and generalized pareto distributions are proposed the theoretical results are illustrated on financial index returns supplementary materials for this article are available online

an essay on post keynesian theory a new paradigm in economics the impact of keynes s work in the 1930 s has been viewed by some economists as a revolution in economic thinking see lawrence r klein 56 1947 yet to those who were most closely associated with keynes at cambridge during that period the revolution proved largely abortive over the past 30 years many of keynes s critical insights into the workings of a modern technologically advanced economy seem to have been ignored with the result that there has been little fundamental change in the way economists perceive the world those one time associates of keynes joined by a small number of the younger generation at cambridge and elsewhere have consistently tried to highlight the incompatibility of keynes s views with orthodox theory even as they worked to develop more fully a generalization of the general theory see joan robinson 78 1952 this generalization may be said to represent in thomas kuhn s sense 62 1962 a new paradigm and since it extends the analysis set forth in keynes s treatise on money 1930 and the general theory it can be termed post keynesian few american economists seem aware of the major works that have contributed to the development of this new paradigm2 and fewer still even among those likely to be sympathetic seem to be aware of the

accounting for retail land sales analysis of a mandated change abstract this study assesses the stock market s reaction to a series of events leading up to a mandated change in accounting for retail land sales evidence is found to support the conclusion that the market reacted to some of these events in a manner consistent with the effects of the accounting change on debt annagement contracts a distinctive aspect of the analysis is the efficient use of security returns data to detect market reactions and to derive empirical distributions of test statistics employed the analysis is extended by a model for grouping regression equations known as seemingly unrelated regressions however the gains from this extension are modest

on rational bubbles and fat tails this paper addresses the statistical properties of time series driven by rational bubbles a la blanchard and watson 1982 using insights on the behavior of multiplicative stochastic processes we demonstrate that the tails of the unconditional distribution emerging from such bubble processes follow power laws exhibit hyperbolic decline more precisely we find that rational bubbles predict a fat power tail for both the bubble component and price differences with an exponent smaller than 1 the distribution of returns is dominated by the same power law over an extended range of large returns although power law tails are a pervasive feature of empirical data these numerical predictions are in disagreement with the usual empirical estimates it therefore appears that exogenous rational bubbles are hardly reconcilable with some of the stylized facts of financial data at a very elementary level

the economic consequences of accounting choice implications of costly contracting and monitoring abstract in this paper we review research into the economic consequences of voluntary and mandatory choices of accounting techniques and standards we discuss how the predictions of extant economic consequence theories are driven by contracting and monitoring costs associated with management compensation contracts bond covenants regulation and or political visibility we review empirical tests of economic consequence theories categorize those tests and discuss their strengths and weaknesses the empirical tests reveal two systematic associations with accounting choice size a proxy for political visibility and leverage a proxy for contracting and monitoring costs of lending agreements interpretation of the results is difficult due to general limitations of the tests we conclude by suggesting some directions for future research based on our analysis of the potential payoffs associated with different types of empirical tests

systemic risk and diversification across european banks and insurers the mutual and cross company exposures to fat tail distributed risks determine the potential impact of a financial crisis on banks and insurers we examine the systemic interdependencies within and across the european banking and insurance sectors during times of stress by means of extreme value analysis while insurers exhibit a slightly higher interdependency in comparison with banks the interdependency across the two sectors turns out to be considerably lower this suggests that downside risk can be lowered through financial conglomeration

optimal portfolio selection in a value at risk framework abstract in this paper we develop a portfolio selection model which allocates financial assets by maximising expected return subject to the constraint that the expected maximum loss should meet the value at risk limits set by the risk manager similar to the mean variance approach a performance index like the sharpe index is constructed furthermore when expected returns are assumed to be normally distributed we show that the model provides almost identical results to the mean variance approach we provide an empirical analysis using two risky assets us stocks and bonds the results highlight the influence of both non normal characteristics of the expected return distribution and the length of investment time horizon on the optimal portfolio selection

relation between market model prediction errors and omitted variables a methodological note a number of accounting studies have examined market model prediction errors to evaluate the share price effects of various events such as voluntary or mandatory accounting changes a common approach is to examine the prediction errors around the event date of a portfolio of potentially affected firms this approach has been extended recently through the use of cross sectional regressions e g leftwich 1981 holthausen 1981 collins rozeff and dhaliwal 1981 sepe 1982 and chow 1983 in which prediction errors or raw returns are regressed on firm specific variables such as size the purpose of this paper is to examine the implications of some recent findings in finance for the various finance based empirical accounting studies in general two types of omitted variables from the standard capital assets pricing model have been identified first several studies have reported that certain firm specific variables such as size banz 1981 and reinganum 1981 earnings yield basu 1975 1983 and dividend payout ratio litzenberger and ramaswamy 1979 may be omitted variables from the standard capm in addition other studies have found some special time series characteristics of stock returns such

growth distribution and inflation a centennial synthesis microeconomics at harvard a little more than a decade ago having become disenchanted with neoclassical economics i suggested to my students that the very neoclassical course i had just taught provided one way of characterising the workings of a capitalist economy but hardly the only way after a year of utility maximisation partial and general equili brium pareto optimality and the associated agonies of lagrangians hessians jacobians and fixed point theorems my students were able to contain their enthusiasm for this news they had expected not one way of looking at the world but at the very least a magical key to knowledge and wisdom it is probably accurate to say that my message was not received at all i shall always remember the incomprehension etched on their faces the next year the last i was to teach theory in that incarnation i decided to present at least a sketch of an alternative to the neoclassical orthodoxy i soon discovered there were at least two foundations on which to build one going back to marx who died one hundred years ago the other deriving from keynes whose birth centenary we celebrate this year these two approaches it was clear were as different from each other as from the neoclassical approach the analysis of neo keynesian neo marxian and neoclassical theories has been a major focus of my research ever since and provides the framework for these lectures 1

international diversification an extreme value approach abstract international diversification has costs and benefits depending on the degree of asset dependence we study international diversification with two dependence measures correlations and extreme dependence we discover that dependence has typically increased over time and document mixed evidence on heavy tails in individual countries moreover we uncover three additional findings related to dependence first the timing of downside risk differs depending on the region surprisingly recent latin american returns exhibit little downside risk second latin america exhibits a great deal of correlation complexity third according to the empirical results correlation does not vary with returns but extreme dependence does vary monotonically with regional returns our results are consistent with a tradeoff between international diversification and systemic risk they also suggest international limits to diversification and that international investors demand some compensation for joint downside risk during extreme events

the siable law model of stock returns this study investigates the tail shapes of empirical distributions of returns on an extensive group of common stocks the tails of the return distributions are found to be thinner than those of infinite variance stable distributions therefore although homogeneity is evident in general economic and statistical inferences drawn from stable law parameters estimated from samples of stock returns may be misleading this is in spite of the apparent overall similarity in shape between empirical and stable distributions

estimating the density tail index for financial time series the tail index of a density has been widely used as an indicator of the probability of getting a large deviation in a random variable most of the theory underlying popular estimators of it assume that the data are independently and identically distributed i i d however many recent applications of the estimator have been to financial data and such data tend to exhibit long range dependence we show via monte carlo simulations that conventional measures of the precision of the estimator which are based on the i i d assumption are greatly exaggerated when such dependent data are used this conclusion also has implications for estimates of the likelihood of getting some extreme values and we illustrate the changed conclusions one would get using equity return data

cross sectional association between abnormal returns and firm specific variables abstract abnormal returns market model prediction errors are the subject of many event studies in accounting and finance literature conditional on the event of interest researchers have recently used cross sectional regressions to examine relations between abnormal returns and firm specific variables this paper demostrates that non constant variences and covariances in market model residuals across firms introduced bias in the estimated slope coefficients of the independent variables i e the expected signs of the estimated slope coefficients can be predicted a priori a method is develope to removed the bias in the estimated slope coefficiets and is found to be effective this method explicitly takes the dependence among abnormal returns across firms into account methods that assume abnormal returns across firms to be independent do not control for such bias

institutional investors and stock market volatility statement of responsibility on t p reads xavier gabaix parameswaran gopikrishnan vasiliki plerou h eugene stanley

extreme us stock market fluctuations in the wake of 9 11 we apply extreme value analysis to us sectoral stock indices in order to assess whether tail risk measures like value at risk and extremal linkages were significantly altered by 9 11 we test whether semi parametric quantile estimates of downside risk and upward potential have increased after 9 11 the same methodology allows one to estimate probabilities of joint booms and busts for pairs of sectoral indices or for a sectoral index and a market portfolio the latter probabilities measure the sectoral response to macro shocks during periods of financial stress so called tail s taking 9 11 as the sample midpoint we find that tail s often increase in a statistically and economically significant way this might be due to perceived risk of new terrorist attacks copyright 2008 john wiley sons ltd

nonlinearities and nonstationarities in stock returns this article addresses the question of whether recent findings of nonlinearities in high frequency financial time series have been contaminated by possible shifts in the distribution of the data it applies a recursive version of the brock dechert scheinkman statistic to daily data on two stock market indexes between january 1980 and december 1990 it is shown that october 1987 is highly influential in the characterization of the stock market dynamics and appears to correspond to a shift in the distribution of stock returns sampling experiments show that simple linear processes with shifts in variance can replicate the behavior of the tests but autoregressive conditional heteroscedastic filters are unable to do so

the probability distribution of foreign exchange price changes tests of candidate processes this study investigates empirically candidate processes for characterizing foreign exchange price changes measured over limited horizons extant empirical studies find distributions of exchange returns too long tailed and leptokurtic to satisfy normality four processes are investigated here because of their potential to model o bserved discontinuities in exchange rates and nonstationary sample moments as well as their economic appeal the results favor a mixed jump model for all six major trading currencies tested copyright 1988 by mit press

effects of early bond refundings abstract this paper examines bond for bond refundings and their effects on stock returns refundings can affect the reported income cash flows including taxes dividend constraints and financial ratios of firms for a sample of 36 nyse and ase firms that performed refundings between 1971 and 1980 stock returns were significantly higher than predicted only around the release of the quarterly earnings announcement that included the refunding s effects while the refundings were found to have many characteristics that were hypothesized to benefit shareholders only the change in earnings per share was found to be associated with the prediction errors further there appears to be no refunding related information released in the quarterly earnings announcement except for the refunding gain these results imply that a portfolio of refunding firms can be created in advance of the quarterly earnings announcement that will generate abnormal returns around the earnings announcement because trading rules are inconsistent with the concept of an efficient capital market these results constitute an anomaly

testing for covariance stationarity in stock market data abstract this paper proposes several non parametric tests for covariance stationarity and applies them to common stock return data from 1834 1987 recursive variance plots post sample prediction tests cumulative sum henceforth cusum tests and modified scaled range tests all show strong non stationarity in stock returns primarily due to the large increase in volatility during the great depression these tests should be useful as diagnostics for data where the assumptions underlying the desired statistical procedure require stationarity

an empirical re examination of extreme tail behavior testing the assumptions of the power laws and the generalized pareto distribution on the financial series this study investigates whether the power laws and the associated generalized pareto distribution gpd exist in the extreme tail behavior of financial return series we include 10 series of five m

stock price reactions as surrogates for the net cash flow effects of corporate policy decisions abstract this paper adopts a rational market structure to examine the link between the cash flow effects of management policy decisions and the resulting stock price reactions the focus is on testing cross sectional associations between cash flow effects and the underlying characteristics of affected firms we find that it is not possible to infer the sign of association between the stock price reaction and any characteristics of the firm that are observable before management announces its decision our methodological suggestions involve exploiting either a priori assumptions or sample information about the probability distribution of unobservable decision variables underlying the management decision process

quantifying and understanding the economics of large financial movements abstract financial market data offer the exciting possibility of quantifying and understanding the physics of a complex dynamical system and the hope that this line of thinking may give some insights into understanding collective human behavior various measures of stock market activity have been found to exhibit puzzling features that have recently attracted much research attention these features include the power law distributions of return volume number of trades assets under management of trading institutions and other power law relations linking them here we review these empirical results and show that some of these findings can be usefully interpreted within the framework of a reduced form model gabaix x gopikrishnan p plerou v stanley h e 2003 a theory of power law distributions in financial market fluctuations nature 423 267 270 and an economic model gabaix x gopikrishnan p plerou v stanley h e 2006b institutional investors and stock market volatility quarterly journal of economics 121 461 504 the features not only present a challenge to models of market fluctuations but their specific power law nature also suggests new modeling directions which include ideas from statistical physics which proved useful in understanding similar relationships that occur in the physics of critical phenomena

unexpected tails in risk measurement some international evidence risk management critically depends on the assumptions made about the distribution of stock returns this paper applies extreme value methods to investigate the limiting distribution of the extreme returns of the nikkei225 ftse100 and s p500 indices as well as the indices of some of largest sectors in japan uk and us the results indicate that the much celebrated generalised extreme value distribution does not provide the most accurate description of the minima since the generalised logistic distribution performs better due to its ability to better capture the fat tails of returns the time varying nature of extremes is also confirmed while a simulation exercise adds to the robustness of our results it is also shown that the findings may have important implications for risk models such as var and expected shortfall since risk measures which cannot capture the fatness of tails of the empirical distribution function of returns may lead to serious underestimation of downside risk

evidence on the effect of bond covenants and management compensation contracts on the choice of accounting techniques the case of the depreciation switch back abstract provisions of bond indenture agreements and management compensation contracts are examined to derive testable implications concerning management s incentives to choose among alternative accounting techniques the hypotheses are subjected to empirical examination by investigating the voluntary change from accelerated to straight line depreciation for financial reporting purposes only the methodology utilized incorporates an expectations model of accounting earnings in an attempt to separate out of the effects of earnings announcements from accounting change announcements which are often concurrent the evidence from both price and non price data is not consistent with the general hypothesis that bond covenants and management compensation contracts are important determinants of the decision to change depreciation techniques five potential explanations for the results are offered

from value at risk to stress testing the extreme value approach this article presents an application of extreme value theory to compute the value at risk of a market position in statistics extremes of a random process refer to the lowest observation the minimum and to the highest observation the maximum over a given time period extreme value theory gives some interesting results about the distribution of extreme returns in particular the limiting distribution of extreme returns observed over a long time period is largely independent of the distribution of returns itself in financial markets extreme price movements correspond to market corrections during ordinary periods and also to stock market crashes bond market collapses or foreign exchange crises during extraordinary periods an approach based on extreme values to compute the var thus covers market conditions ranging from the usual environment considered by the existing var methods to the financial crises which are the focus of stress testing univariate extreme value theory is used to compute the var of a fully aggregated position while multivariate extreme value theory is used to compute the var of a position decomposed on risk factors 2000 elsevier science b v all rights reserved

atheoretical macroeconometrics a critique abstract the spurious nature of the restrictions used to identify many macroeconometric models has led some researchers to advocate a style of econometric inquiry that is less dependent on prior theoretical restrictions of the sort that were central to the approach of the cowles commission this development which we call atheoretical macroeconometrics is summarized and evaluated in the current paper it is contrasted with an updated version of the cowles commission approach we conclude that while some of the exercises of atheoretical macroeconometrics are valid those that have attracted the most attention and appear the most innovative exogeneity testing impulse response analysis and policy analysis using estimated vector autoregressions are based on incorrect analysis

testing for multiple regimes in the tail behavior of emerging currency returns it is by now generally accepted that foreign exchange returns exhibit heavy tails as measured by the so called tail index however it is unclear whether the tail behavior remains stationary in the presence of recurrent switches in the exchange rate regime we therefore test the null hypothesis of tail index constancy by applying a single breaks test in rounds which enables the detection of multiple breakpoints we are able to identify multiple jumps in the tail index of currency returns moreover some breaks coincide with documented shifts in monetary and exchange rate policies

deducing the implications of jump models for the structure of stock market crashes rallies jump arrival rates and extremes this article studies the structure of stock market crashes rallies their jump arrival rates and extremes large market moves are characterized in a pure jump modeling framework based on both raw and devolatized returns it is shown empirically that crashes are more severe in intensity than rallies and have higher arrival rates at the same time both left tail and right tail extreme events conform with frechet limit laws pure jump models which describe well the tail properties of market returns are identified via their levy measures the distribution of extreme events implied by our model s levy measure is closer to the actual realization of extremes than those of competing models finally there is information content in the levy measure of pure jump models for forward arrival rate of jumps

the economic value of fundamental and technical information in emerging currency markets abstract we measure the economic value of information derived from macroeconomic variables and from technical trading rules for emerging markets currency investments our analysis is based on a sample of 21 emerging markets with a floating exchange rate regime over the period 1997 2007 and explicitly accounts for trading restrictions on foreign capital movements by using non deliverable forward data we document that both types of information can be exploited to implement profitable trading strategies in line with evidence from surveys of foreign exchange professionals concerning the use of fundamental and technical analysis we find that combining the two types of information improves the risk adjusted performance of the investment strategies

evidence of the impact of mandatory changes in accounting principles on corporate loan agreements abstract the theory in this paper predicts that mandatory changes in accounting princples can affect the measurement rules defined in restrictive covenants in firms lending agreements consequently those mandatory changes can have an impact on the value of a firm s equity even if the changes appear to be merely cosmetic this contracting cost theory is tested by examining of both event related and cross sectional abnormal performance of the equity of a sample of firms when the accounting princples board changes accounting princples for business combinations the theory provides at best in incomplete explanation of the observed abnormal performance

an approach to statistical inference in cross sectional models with security abnormal returns as dependent variable several recent event studies test hypotheses about the association between event related abnormal security returns and firm characteristics using a three step procedure first forecast model parameters are estimated usually parameters of a market model second prediction errors or residuals are computed over an event period third prediction errors are regressed cross sectionally on firm characteristics hypothesized to influence the impact of the event on share values results of these regressions are used to draw inferences about the relation between abnormal returns and firm characteristics researchers who employ three step procedures acknowledge that crosssectional ols regressions lead to valid inferences if the disturbances are iid normal in cross section see for example leftwich 1981 p 23 and lustgarten 1982 p 138 while sufficient assumptions to draw valid inferences from ols regressions are clear these assumptions are violated if there is cross correlation and cross sectional heteroscedasticity in the firm return processes from which the prediction errors are estimated assumptions about the processes generating these prediction

distribution properties of latin american black market exchange rates abstract this paper conducts a statistical analysis of the distribution properties of black market exchange rate changes for 12 latin american currencies the infinite variance stable law hypothesis is tested using a regression type technique to estimate the parameters of the stable paretian distribution strong evidence is found supporting this hypothesis a separate analysis of extreme observations using a robust statistical procedure further supports these findings

profits investment and causality an examination of alternative paradigms determinants of the level of profits and the share of these profits in national income in the short run have received only limited attention from economists most paradigms such as the neo classical neo keynesian and neo marxian theories have in general attempted to explain distributive shares in long run equilibrium disequilibrium or steady state growth frameworks further there is little discussion of the behavioral relationships of various economic agents who affect and are affected by changes in distributive shares kalecki 19 argued for determination of profits and wages by the expenditure behavior of capitalists and by the distribution factors such as the degree of monopoly in output and input markets particularly the labor market 2 capitalists expenditure together with the distribution factors determine workers consumption and consequently national output and employment the national output will be pushed to the point where profits carved out of it in accordance with the distribution factors are equal to the sum of capitalists consumption and investment 19 81 further kalecki argued at length that given the distribution factors in the short run it is their capitalists consumption and investment that determine profits and not vice versa 19 79 similar behavioral roles of different economic classes are emphasized in the works of keynes 20 kaldor 18 and pasinetti 25 keynesians neo keynesians also ascribe a leading role to investment however there are differences in detail between the popular keynesian paradigm and that of keynes s own work 10 23 neo classical theory on the other hand seems to reverse this direction of causation between investment and profits due to the absence of an independent investment function

the choice of the distribution of asset returns how extreme value theory can help abstract one of the issues of risk management is the choice of the distribution of asset returns academics and practitioners have assumed for a long time for more than three decades that the distribution of asset returns is a gaussian distribution such an assumption has been used in many fields of finance building optimal portfolio pricing and hedging derivatives and managing risks however real financial data tend to exhibit extreme price changes such as stock market crashes that seem incompatible with the assumption of normality this article shows how extreme value theory can be useful to know more precisely the characteristics of the distribution of asset returns and finally help to chose a better model by focusing on the tails of the distribution an empirical analysis using equity data of the us market is provided to illustrate this point

event study methodologies and the size effect abstract this study of 862 press recommendations demonstrates that the size effect can distort longer term performance measures and hence event studies relative to similar sized companies post publication performance is neutral however market adjustments the capm and market model with equally or capitalization weighted indexes all produce biased results event studies are most exposed to such bias when the measurement interval is long event securities differ systematically in size or weighting from the index constituents the size effect is large and or volatile and when capm type methodologies are used these distortions are avoided by explicitly controlling for size

long term asset tail risks in developed and emerging markets a power law typically governs the tail decay of financial returns but the constancy of the so called tail index which dictates the tail decay remains relatively unexplored we study the finite sample properties of some recently proposed endogenous tests for structural change in the tail index given that the finite sample critical values strongly depend on the tail parameters of the return distribution we propose a bootstrap based version of the structural change test our empirical application spans developed and emerging financial asset returns somewhat surprisingly emerging stock market tails are not more inclined to structural change than their developed counterparts emerging currency tails on the contrary do exhibit structural shifts in contrast to developed currencies our results suggest that extreme value theory evt applications in hedging tail risks can assume stationary tail behavior over long time spans provided one considers portfolios that solely consist of stocks or bonds

asset market linkages in crisis periods we characterize asset return linkages during periods of stress by an extremal dependence measure contrary to correlation analysis this nonparametric measure is not predisposed toward the normal distribution and can allow for nonlinear relationships our estimates for the g 5 countries suggest that simultaneous crashes between stock markets are much more likely than between bond markets however for the assessment of financial system stability the widely disregarded cross asset perspective is particularly important for example our data show that stock bond contagion is approximately as frequent as flight to quality from stocks into bonds extreme cross border linkages are surprisingly similar to national linkages illustrating a potential downside to international financial integration

on the frequency of large stock returns putting booms and busts into perspective textabstractnumerous articles have investigated the distribution of share prices and find that the returns are fat tailed nevertheless there is still controversy about the amount of probability mass in the tails and hence about the most appropriate distribution to use in modeling returns this controversy has proven hard to resolve as the alternatives are non nested we employ extreme value theory focusing exclusively on the larger observations in order to assess the tail shape within a unified framework we find that at least the first two moments exist this enables one to generate robust probabilities on large returns which put the recent stock market swings into historical perspective

the asymptotic distribution of extreme stock market returns this article presents a study of extreme stock market price movements according to extreme value theory the form of the distribution of extreme returns is precisely known and independent of the process generating returns using data for an index of the most traded stocks on the new york stock exchange for the period 1885 1990 the author shows empirically that the extreme returns obey a frechet distribution copyright 1996 by university of chicago press

the day of the week effect the international evidence abstract we re examine the day of the week effect for eleven indexes from nine countries during the 1969 1992 period the standard methodology as well as the moving average methodology are used and we find returns to be lower at the beginning of the week but not necessarily on monday for the full period as in chang et al international evidence on the robustness of the day of the week effect journal of financial and quantitative analysis 28 1993 497 514 the anomaly disappears for the most recent period in the usa however the effect is still strong for european countries hong kong and toronto

the effect of value line investment survey rank changes on common stock prices abstract the information content of value line investment survey rank changes is investigated the results suggest rank changes affect common stock prices but the effect varies by the type of rank change changes from rank 2 to rank 1 have the most dramatic impact on prices a cross sectional analysis finds small firms have a greater reaction to a rank change than larger firms which supports theories on the frequency of report arrival and precision of information a speed of adjustment test concludes the prices of individual securities adjust to the information in a rank change over a multiple day period

dependence structure between the equity market and the foreign exchange market a copula approach abstract this paper investigates the dependence structure between the equity market and the foreign exchange market by using copulas in particular several copulas with different dependence structure are compared and used to directly model the underlying dependence structure we find that there exists significant symmetric upper and lower tail dependence between the two financial markets and the dependence remains significant but weaker after the launch of the euro our findings have important implications for both global investment risk management and international asset pricing by taking into account joint tail risk

prudent margin levels in the finnish stock index futures market futures market officials are confronted with the difficult task of setting appropriate margin levels that must balance the costs of trader default and the benefits of increased market liquidity one way to guard against default is prudent margin setting practices designed to protect futures positions from extreme price movements the objective of this research is to extrapolate the probabilities of encountering extreme price movements by applying statistical extreme value theory to the finnish stock index futures market the extreme value technique is found to be appropriate since it generates theoretical margin violation probabilities that closely follow the empirical probability distribution the extrapolated results provide decision makers information on extreme events that have not yet occurred

on cross sectional analysis in accounting research abstract this paper examines cross sectional analysis procedures common to many market based accounting research papers both the economic and econometric properties of levels and returns studies are discussed topics covered include the relations between the accounting studies and cash flow valuation models the role of expectations of accounting variables deflators spurious inference risk adjustment and its relation to growth size and leverage residual dependence dependence among explanatory variables and the effect of scale differences across firms major conclusions are that market value is the correct deflator in returns studies and that levels and returns studies are economically but not econometrically equivalent

mandated accounting changes and debt covenants the case of oil and gas accounting abstract the relationships among mandated accounting changes bond covenants and security prices has been the focus of several studies these studies have provided mixed evidence on the existence of a bond covenant effect on security prices this paper suggests that inconclusive prior results are a consequence of inappropriately measuring the default risk of debt using an option pricing framework it is shown that the debt to equity alone is not an adequate measure of default risk in particular both the debt to equity ratio and the total risk of the firm are necessary to adequately model the bond covenant effects of an accounting change these theoretical propositions are supported by the empirical analysis of the security market reaction to changes in oil and gas accounting

systemic risk and bank business models textabstractin this paper we decompose banks systemic risk into two dimensions the risk of a bank bank tail risk and the link of the bank to the system in financial distress systemic linkage based on extreme value theory we estimate a systemic risk measure that can be decomposed into two subcomponents reflecting these dimensions empirically we assess the relationships of bank business models to the two dimensions of systemic risk the observed differences in these relationships partly explain why micro and macroprudential perspectives sometimes have different implications for banking regulation

simulating and calibrating diversification against black swans abstract an investor concerned with the downside risk of a black swan only needs a small portfolio to reap the benefits from diversification this matches actual portfolio sizes but does contrast with received wisdom from mean variance analysis and intuition regarding fat tailed distributed returns the concern for downside risk and the fat tail property of the distribution of returns can explain the low portfolio diversification a simulation and calibration study is used to demonstrate the relevance of the theory and to disentangle the relative importance of the different effects

heteroskedasticity robust panel unit root tests this article proposes new unit root tests for panels where the errors may be not only serial and or cross correlated but also unconditionally heteroscedastic despite their generality the test statistics are shown to be very simple to implement requiring only minimal corrections and still the limiting distributions under the null hypothesis are completely free from nuisance parameters monte carlo evidence is also provided to suggest that the new tests perform well in small samples also when compared to some of the existing tests supplementary materials for this article are available online

mixed diffusion jump process modeling of exchange rate movements this study demonstrates that the mixed diffusion jump process is superior to the stable laws or a mixture of normals as a model of exchange rate changes for the british pound french franc and the we st german mark relative to the united states dollar the parameter value s for the mixed diffusion jump process are dependent on the monetary policy regime in force in the united states with the estimates for the franc and mark being intertemporally similar but different from the pound copyright 1988 by mit press

modeling heteroscedasticity in daily foreign exchange rates this article estimates autoregressive conditionally heteroscedastic arch and generalized arch garch models for five foreign currencies using 10 years of daily data a variety of arch and garch specifications a number of nonnormal error densities and a comprehensive set of diagnostic checks it finds that arch and garch models can usually remove all heteroscedasticity in price changes in all five currencies goodness of fit diagnostics indicate that exponential garch with certain nonnormal distributions fits the canadian dollar extremely well and the swiss franc and the deutsche mark reasonably well only one nonnormal distribution fits the japanese yen reasonably well none fit the british pound

tail relation between return and volume in the us stock market an analysis based on extreme value theory abstract using daily data of the s p 500 index from 1950 to 2015 we investigate the relation between return and transaction volume in the statistical distribution tails associated with booms and crashes in the us stock market we use extreme value theory peaks over threshold method to study the extreme dependence between the two variables we show that the extreme correlation between return and volume decreases as we consider larger events in both the left and right distribution tails from an economic viewpoint this paper contributes to a better understanding of the activity of market participants during extreme events our empirical result is consistent with the economic explanation by gennotte and leland 1990 of extreme price movements based on misinterpretation of trades by market participants

the economic determinants of the market reaction to proposed mandatory accounting changes in the oil and gas industry a cross sectional analysis abstract this paper examines the economic reasons for the observed negative abnormal common stock performance of firms whose reported earnings and stockholders equity were negatively affected by the proposed elimination of full cost accounting in the oil and gas industry four explanations of the market effects of this mandatory accounting change are examined 1 naive investor theory 2 modified naive investor theory 3 contracting cost theory and 4 estimation risk theory these hypotheses are developed in detail and used to generate variables for a cross sectional model which explains observed return behavior the effect of the accounting change on total stockholder s equity the existence of financial contracts denominated in terms of accounting numbers and to a lesser extent firm size are shown to be important explanatory variables the importance of these variables is consistent with both the contracting cost and estimation risk theories

extreme value theory in finance a survey extreme value theory is concerned with the study of the asymptotic distribution of extreme events that is to say events which are rare in frequency and huge in magnitude with respect to the majority of observations statistical methods derived from it have been employed increasingly in finance especially for risk measurement this paper surveys some of those main applications namely for testing different distributional assumptions for the data for value at risk and expected shortfall calculations for asset allocation under safety first type constraints and for the study of contagion and dependence across markets under conditions of stress

robust tests of forward exchange market efficiency with empirical evidence from the 1920s summary this paper provides a robust statistical approach to testing the unbiasedness hypothesis in forward exchange market efficiency studies the methods we use allow us to work explicitly with levels rather than differenced data they are statistically robust to data distributions with heavy tails and they can be applied to data sets where the frequency of observation and the futures maturity do not coincide in addition our methods allow for stochastic trend non stationarity and general forms of serial dependence the methods are applied to daily data of spot exchange rates and forward exchange rates during the 1920s which marked the first episode of a broadly general floating exchange rate system the tail behaviour of the data is analysed using an adaptive data based method for estimating the tail slope of the density the results confirm the need for the use of robust regression methods we find cointegration between the forward rate and spot rate for the four currencies we consider the belgian and french francs the italian lira and the us dollar all measured against the british pound we find support for a stationary risk premium in the case of the belgian franc the italian lira and the us dollar and we find support for the simple market efficiency hypothesis where the forward rate is an unbiased predictor of the future spot rate and there is a zero mean risk premium in the case of the us dollar

structural change test in duration of bull and bear markets abstract we propose a recursive test to analyze structural changes in duration of bull and bear markets using the dow jones industrial average index we detected a single structural break in the bull market duration in april 1942