ON THE IDENTIFICATION OF INTERDEPENDENCE AND CONTAGION OF FINANCIAL CRISES EMANUELE BACCHIOCCHI Working Paper n. 2015-12 LUGLIO 2015 FRANCESCO GUALA Working Paper n. 2011-18 SETTEMBRE 2011 ARE PREFERENCES FOR REAL? CHOICE THEORY, FOLK PSYCHOLOGY, DIPARTIMENTO DI ECONOMIA, MANAGEMENT E METODI QUANTITATIVI AND THE HARD CASE FOR COMMONSENSIBLE REALISM Via Conservatorio 7 20122 Milano tel. ++39 02 503 21501 (21522) - fax ++39 02 503 21450 (21505) FRANCESCO GUALA http://www.economia.unimi.it E Mail: [email protected] Working Paper n. 2011-18 On the Identification of Interdependence and Contagion of Financial Crises Emanuele Bacchiocchi⇤ July 2015 Abstract In this paper we propose a new framework for modeling heteroskedastic structural vector autoregressions. Although it is general enough to find potential applications in many empirical economic fields, it reveals to be well suited in the distinction between interdependence and contagion in the literature related to the transmission of financial crises. The identification of the structural parameters is obtained by exploiting the heteroskedasticity in the data, naturally arising during crisis periods. More precisely we provide identification conditions when both heteroskedasticity and traditional restrictions on the parameters are jointly considered. Finally, this methodology is used to investigate the relationships between sovereign bond yields for some highly indebted EU countries. Keywords: Heteroskedasticity, identification, interdependence, contagion, highly indebted EU countries, financial crisis. JEL codes: C01,C13,C30,C51. ⇤ DEMM, University of Milan, Via Conservatorio 7, 20122 Milan (Italy), tel +39 02 50321504, fax +39 02 50321450. Email: [email protected] 1 I Introduction The recent global crisis and the subsequent European debt sovereign crisis, in their drama, o↵er economists and econometricians a rich laboratory to study the transmission of financial shocks during periods of high turbulences. Since the seminal contribution by King and Wadhwany (1990) many studies have been proposed to capture the rational and irrational aspects of the spreads of financial crises. Contagion is the term which mainly represents this stream of research, although over the years, other definitions were proposed according to the di↵erent theoretical explanations causing this phenomenon. Masson (1999), for example, distinguishes between monsoonal e↵ects, spillovers, and pure contagion. While the first two are mainly related to macroeconomic fundamentals and external economic linkages, the last one indicates all those cases when the co-movements can be considered as “excessive”. The definition of contagion we have in mind for the aim of the present paper is to look at whether shocks propagate di↵erently during normal or turbulent periods, indicated as “shift contagion” by Caporin et al., 2013. From the empirical point of view, the literature is huge. Di↵erent approaches have been proposed and many international crises investigated (see Dungey et al, 2005, Bacchiocchi and Bevilacqua, 2009, and Caporin et al., 2013, for surveys). A consistent class of papers, in particular, proposes empirical tests for financial contagion by observing whether the correlations between di↵erent markets are significantly higher during crisis periods. In this line of research Forbes and Rigobon (2002) point to the importance of the distinction between the so called “interdependence”, indicating the market co-movements occurring even in periods of stability, and the “pure contagion” effects, occurring only if cross-markets co-movements increase significantly after the shock. Their approach is based on correcting the traditional tests for comparing cross-market correlations for the upward bias caused by heteroskedasticity, naturally arising during crises. Once correcting for this bias, they find that for many crises occurred during the ’90s the observed high cross-market correlations are mainly attributed to interdependence rather than contagion. This approach, however, is not immune to the endogeneity problem, i.e. when there are bi-directional simultaneous linkages between the two investigated countries (the originating and the a↵ected countries). Rigobon (2003a), instead, in studying the propagation of shocks proposes a test for parameter stability, taking into account the econometric problems that generally arise when one investigates market relationships during high turbulent periods, i.e. simultaneous equations, omitted variables and heteroskedasticity. The paper, however, does not make any distinction between the two possible transmission channels “interdependence” and “contagion”. Ciccarelli and Rebucci’s (2007) work also represents an important contribution to the analysis of transmission of financial shocks. They propose a time-varying coefficient model to measure contagion and interdependence in a Bayesian framework, that jointly deals with the presence of heteroskedasticity and omitted variables. The time-varying nature of the coefficients, moreover, may be used without knowledge of the e↵ective timing of the crisis prior to the empirical analysis. However, as recognized by the authors, they do not attempt to address the possible simultaneity problems that might arise when modeling strictly linked countries or markets1 . 1 The authors suggest to deal with the possible endogeneity problem by means of potential extensions of the time-varying coefficients structural VAR models used by Cogley and Sargent (2005) and Ciccarelli and Rebucci (2006) 2 In the present paper, instead, we concentrate on this last problem and propose a solution based on a new specification of structural vector autoregressive (SVAR) models that explicitly accounts for possible heteroskedasticity of the endogenous variables which is exploited to identify di↵erent volatility regimes. Such heteroskedasticity is thus used to understanding whether the transmission of shocks is di↵erent across di↵erent volatility regimes. As an example, in periods of high instability of the financial markets, a shock hitting one particular market might propagate in a di↵erent way than in relatively tranquil periods. The e↵ect of the same shock, in di↵erent periods of time, might be completely di↵erent. The turbulences of the market could either amplify the e↵ect of the shock in the same market in which it originates, or allow for a propagation to other financial markets, or both the e↵ects. In this context, the proposed model, although general enough to find potential applications in many macro-economic and financial frameworks, reveals to be well suited for the distinction between interdependence and contagion of financial markets as discussed above. The particular structure of the model, in fact, helps in the distinction between these two phenomena, while the endogeneity drawback highlighted by Forbes and Rigobon (2002) is solved through the recent “identification through heteroskedasticity” proposed by Rigobon (2003b). The intuition, originally introduced by Wright (1928), consists in using the second moments to increase the number of relations mapping the parameters of the reduced and structural forms. Lanne and Lütkepohl (2008) and Lanne et al. (2010) use the same idea to identify the structural shocks in SVAR models. As will be shown in the next sections, the specification introduced in the present paper reveals to be more general than those proposed by Rigobon (2003b) and Lanne and Lütkepohl (2008). The paper also introduces novel identification rules for heteroskedastic SVAR models that encompasses previous ones. To the best of our knowledge, the most similar contributions to our approach are Dungey et al (2010) and Dungey et al (2015). In the former, the authors use a multivariate identified GARCH model and distinguish between tranquil periods, hypersensitivity and contagion between Hong Kong, Indonesia, Korea and Thailand, over the period 1997-98. In the latter, instead, the focus is on crises dating using smooth transition structural GARCH model, with an application to US equity, bond and REIT returns for 2001-10. Similarly to our model, contagion can be detected by looking at possible changes in the simultaneous relationships among the investigated variables. Another related paper is Kosch and Caporin (2013), that extends the Dynamic Conditional Correlation (DCC) multivariate GARCH by including a threshold structure for the dynamics of the correlations. This model allows the authors to show that, when considering a set of stock markets in 1994-2011, periods of market turmoils are associated with higher market comovements. This paper, however, does not discriminate between interdependence and contagion, but rather corrects the dynamic correlations from the presence of heteroskedasticity as in the spirit of Forbes and Rigobon (2002). Over the last years other authors have proposed approaches to obtain identification using heteroskedasticity in the data. Klein and Vella (2010) use the heteroskedasticity of the residuals to identify the structural parameters in bivariate triangular systems. Prono (2013) also discusses identification in linear bivariate triangular models where structural errors follow a bivariate and diagonal GARCH(1, 1) process. Lewbel (2010), instead, considers bivariate models with mismeasured or endogenous regressors. Identification in triangular and fully simultaneous systems can be obtained by imposing restrictions on particular second moments involving regressors and heteroskedastic residuals. Bacchiocchi and Fanelli (2015) propose an heteroskedastic SVAR model with structural breaks. Sentana and Fiorentini (2001), in a context of conditionally heteroskedastic factor models, provide identification 3 conditions that can be applied in a large number of cases, like residuals following GARCH specifications2 , regime switching processes3 or structural VAR models4 . On one side, in our innovative specification for heteroskedastic SVAR models, the presence of di↵erent volatility regimes facilitates the identification of the interdependence among financial markets when a priori restrictions on the direction of causality cannot be imposed. More generally, and this is new to the best of our knowledge, identification conditions will be provided when the heteroskedasticity in the data is mixed with the traditional approach of imposing restrictions on the structural parameters of the model. On the other side, the new transmission channels operating in high turbulent periods provide evidence on the contagion e↵ects. A test for contagion, thus, simply becomes a test on the parameters related to these further transmission channels. The methodology developed in the paper is used to study the transmission of financial shocks in some highly indebted EU countries during the recent global and debt crises: Spain, Ireland, Portugal, Greece and Italy. Being part of a common market these countries are highly connected one to the others. Moreover, during the recent turbulences all these countries have played a proactive role in the propagation of (negative) financial shocks, making impossible to discriminate between originating and a↵ected countries. The assumption of no endogeneity considered in many empirical contributions in the literature of contagion, such as Forbes and Rigobon (2002) and Ciccarelli and Rebucci (2006), becomes seriously questionable.5 While the empirical literature on contagion is huge, only few contributions explicitly focus on the e↵ects of the recent financial and debt crises within the European Monetary Union (EMU). One of these is the already mentioned work by Caporin et al (2013), that using univariate quantile regression techniques find almost no presence of contagion over the sample 2003-2013, for some European countries. Arezki et al (2011), using a VAR with dummies, investigate the spillover e↵ects of rating news on some European credit and financial markets over the period 2007-2010, excluding thus the more recent events of the sovereign debt crisis. De Santis (2012) studies the factors a↵ecting the sovereign bond yields. Using daily observations for the period September 2008-August 2011, he finds that sovereign spreads are explained by an aggregate regional risk factor, by country-specific credit risk and by spillover e↵ects from Greece. Giordani et al (2013), distinguish between “wake-up-call” and pure (or shift) contagion and find that only the former occurred among nine euro-area countries during the period 2000-2011. The results obtained using our procedure, that accounts for possible endogeneity and heteroskedasticity, show that these countries are characterized by strong and bidirectional interdependence. During the recent financial and debt crises, the transmission of financial shocks is completely changed and in some cases there is strong evidence of contagion. The rest of the paper is organized as follows. In Section II we first present the statistical model and then derive the conditions for identification of the structural parameters. Section III uses this methodology to investigate the transmission of financial shocks among some highly indebted EU countries over the last years. Section IV provides some concluding remarks. 2 See Caporale, Cipollini and Demetriades (2005), Dungey and Martin (2001), King et al. (1994), Rigobon (2002). 3 See Caporale, Cipollini and Spagnolo (2005) and Rigobon and Sack (2003, 2004). 4 See Normandin and Phaneuf (2004). 5 This issue has been discussed and addressed in Caporin et al (2013), too. 4 II Modeling Interdependence and Contagion through a new class of heteroskedastic structural VAR models Periods of financial crises are characterized by clusters of higher volatility that, following Forbes and Rigobon (2002), invalidate tests for contagion based on correlation coefficients. Moreover, the two authors, using simulation exercises, highlight that endogeneity also biases these kinds of tests for contagion. In the present section we propose a general econometric framework that allows for both endogeneity and heteroskedasticity in the data. II.1 A structural VAR model with heteroskedastic errors In this section we present a new specification for structural vector autoregressions that explicitly model the heteroskedasticity features of the data. Let the data generating process (DGP) follows a VAR model of the form yt = Ddt + A1 yt 1 + · · · + Ap yt p + ut (1) where yt is a g-dimensional vector of observable variables, dt is a set of deterministic components with related coefficients D, A1 , A2 , . . . , Ap are matrices of parameters, and ut a vector of innovations characterized by s regimes of di↵erent covariance matrices ⌃i , i.e. ut ⇠ L (0, ⌃i ) with i = 1 . . . s. The structural form of the model, connecting the observable variables yt or, concentrating out the dynamics, the innovations ut , with the uncorrelated heteroskedastic shocks "t ⇠ L (0, ⇤t ), can be written as Aut = Bi (t 2 Ti ) "t , E "t "0t = ⇤i t 2 Ti for (2) where Ti collects all the time periods such that regime i is in place, and (·) is the indicator function. Given the heteroskedasticity nature of the structural shocks, described by the ⇤i diagonal matrices, an equivalent representation of the connections between the structural and reduced forms of the model is given by ⌃i = A 1 Bi ⇤i Bi0 A0 1 , i = 1 . . . s. The time-invariant A matrix contains all the parameters describing the simultaneous relations among the observable variables. The time-varying Bi matrices, instead, contain regime-specific structural parameters describing further transmission channels for the structural shocks, operating during each regime. Moreover, as already mentioned, such structural shocks are allowed to have di↵erent (diagonal) covariance matrices ⇤i . Remark 1. Rigobon (2003b) provides a sufficient rank condition for the identification of a bivariate simultaneous equation model characterized by s = 2 volatility regimes. Lanne and Lütkepohl (2008), using a well known result from matrix algebra, generalize the Rigobon’s result by considering heteroskedastic SVAR models for more than two observable variables. In particular, their specification features the following relations ⌃1 = A 1 ⇤1 A 10 and ⌃2 = A 1 ⇤2 A 10 . (3) The generalization to s > 2 is straightforward and can be obtained by considering a constant A matrix and regime-specific ⇤i covariance matrices for the structural shocks, with i = 1, . . . , s. This specification, as can be easily seen, can be obtained as a special case of the SVAR model in Eq.s (1)-(2) when all Bi matrices are restricted to be unit diagonal, 5 i.e. Bi = Ig for i = 1, . . . , s. This di↵erence is substantial in that, in the Lanne and Lütkepohl’s model, once re-scaled, the impulse response functions (IRFs) do not change across the di↵erent volatility regimes, while in our specification, they can change according to the di↵erent further transmission channels provided by the Bi matrices.⌅ Structural breaks in the dynamics of the VAR model The DGP in Eq. (1) is characterized by constant dynamics and regime-specific covariance matrices ⌃i . It might be the case, as for instance in the empirical analysis in Section III, that the VAR model is not stable over time, requiring regime-specific dynamics as well. In this latter case all the reduced-form parameters will be regime-specific and, similarly to the structural parameters, denoted by Di , A1i , . . . , Api , ⌃i , i = 1, . . . , s. This case, that will be discussed in more details in the empirical analysis, does not alter the structural characteristics of the model previously discussed. Under the assumption of known break dates, the estimation of the reduced-form parameters can be performed separately in each regime. In the opposite situation, when there are no changes in both the dynamics and the structural parameters of the model, i.e. Bi = B and ⇤i = Ig , the model reduces to the traditional AB-SVAR model in the terminology of Amisano and Giannini (1997) and Lütkepohl (2005). Unit roots and Cointegration If some of the variables appear to be non-stationary, it would be more convenient to move to the Vector Error Correction (VECM) notation yt = Ddt + ↵ 0 yt 1 + yt 1 1 + ··· + p 1 yt p+1 + ut (4) where is the di↵erencing operator, the full column rank g ⇥ r matrices ↵ and are the adjustment coefficients and the cointegration matrix, respectively, r is the number of cointegrating relations, while j = (Aj+1 + . . . + Ap ), for j = 1, . . . , p 1. The structural form of the model easily becomes A yt = D ⇤ d t + ↵ ⇤ 0 yt 1 + ⇤ 1 yt 1 + ··· + ⇤ p 1 yt p+1 + Bi (t 2 Ti ) "t (5) where D⇤ = AD, ↵⇤ = A↵, ⇤i = A i and where E ("t "0t ) = ⇤i , for t 2 Ti . Furthermore, as for the simple VAR model discussed before, if the structural breaks are not confined to the second moments but involve the dynamics of the model as well, under the assumption of known break dates, the reduced-form VECM can be studied separately in each regime. Interdependence and Contagion The specification discussed above, thus, allows to distinguish between relationships that remain constant over the whole sample, and others that are regime-specific. Going back to the core of the present paper, this is well suited to model interdependence and contagion of financial crises. In particular, the interdependence relations among markets, that remain constant both in tranquil and turbulent periods, can be captured through the A paramet- 6 ers, while the further relationships among the shocks, generally appearing during turmoil periods, characterizing the pure contagion phenomenon, are described by the Bi matrices. The transmission of shocks, thus, is much more complicated than in standard SVAR models and is given by the combination of a) the natural linkages between two or more markets (interdependence) and b) the e↵ect of contagion operating in each specific regime. This point will be largely discussed in the empirical analysis in Section III. II.2 Identification As is known, all SVAR models su↵er from identification problems, which are generally solved by imposing restrictions on the structural parameters. Our specification is not immune to such a problem, although the heteroskedasticity in the data may solve or, at least, alleviate it. In fact, as originally proposed by Rigobon (2003b) the di↵erent clusters of volatility provides a useful source of information that can be used in the identification of the parameters of the structural form of the model. The approach we follow in the present paper is to mix the heteroskedasticity present in the data with the traditional approach consisting of imposing restrictions on the parameters. The A, B1 , . . . , Bs , ⇤1 , . . . , ⇤s parameters, thus, can be subjected to linear restrictions of the form: 0 1 0 1 0 1 0 a SA sA A B b1 C B C B C B S S · · · S s B11 B12 B1s B C B C B B1 C B B1 B b C B C B C B s SB22 · · · SB2s B 2 C B C B B2 C B B2 B . C B C B C B . . . . B .. C B C B .. C B .. .. .. B C B C B C B + B B C = B C B C B bs C B C B Bs C B s Bs SBss B C B C B C B B 1 C B C B C B s⇤1 S ⇤ ⇤ 1 1 B C B C B C B B .. C B C B C B .. . .. @ . A A @ .. A @ . @ . S⇤ s s ⇤s s ⇤s ✓ g 2 (2s+1)⇥1 = S + g 2 (2s+1)⇥(pA +pB +p⇤ ) (pA +pB +p⇤ )⇥1 s Assumption 1 The reduced form innovations are distributed as a multivariate normal variable with time-varying covariance matrix for t 2 T Bi (7) where, ⌃i = A 1 Bi ⇤i Bi0 A0 1 6 , i = 1, . . . , s. (8) This is the explicit notation for imposing restrictions on the parameters. An equivalent way is represented by the implicit form R✓ = r where the p = pA + pB + p⇤ columns of the S matrix form a basis for the null space of the rows of R, so that RS = [0]. 7 C C C C C C C C C C C C C A g 2 (2s+1)⇥1 (6) where a = vec A, bi = vec Bi and i = vec ⇤i , while pA , pB = pB1 +. . .+pBs and p⇤ = p⇤1 + 0 , 0 ,..., 0 , 0 ,..., . . .+p⇤s are the number of free parameters to be estimated in = A B1 Bs ⇤1 The restrictions in Eq. (6) allow for cross restrictions in the parameters contained in the Bi matrices. This will be extremely useful in the empirical analysis in Section III, when some parameters of the Bi matrices are imposed to not change among di↵erent regimes. The following assumptions formalize some concepts previously introduced: ut ⇠ N (0, ⌃i ) 1 0 6 0 ⇤s . Assumption 2 The g ⇥ g matrices of parameters A, Bi and ⇤i , i = 1, . . . , s, are non singular. Assumption 1 describes the distributional aspects of the error terms of the VAR model, which show a time-varying covariance matrix modeled as a function of the structural parameters characterizing the di↵erent volatility states7 . In the traditional literature on SVAR models, Assumption 2 refers to the invertibility of the A and B matrices. In our framework, instead, it is required that all Bi matrices are non-singular. Throughout, use is made of the following notation: Kg is the g 2 ⇥g 2 commutation matrix as defined in Magnus and Neudecker (2007), Ng = 1/2 Ig2 + Kg . The g ⇥ g 2 full-row rank matrix Ug , instead, defined in Magnus (1988), is such that Ug0 w (M ) = vec (M ) with the g⇥1 vector w (M ) = (m11 , m22 , . . . , mss )0 , relating the vector w (M ) to the diagonal elements in the diagonal g ⇥ g matrix M . The following proposition presents the necessary and sufficient condition for identification of the structural parameters. Proposition 1 Consider the SVAR model with s regimes of volatility described in Eq.s (1)(2). Under Assumptions 1-2, then (A, B1 , . . . , Bs , ⇤1 , . . . , ⇤s ) are locally identified if and only if the following sg 2 ⇥ p matrix 0 2Ng B1⇤ 2Ng A⇤1 .. . B @ 2Ng Bs⇤ A .. . 1B 1 ⌦A 1B 1 1 Ug .. . 2Ng A⇤s A 1B s A⇤1 , . . . , A⇤s , B1⇤ , . . . , Bs⇤ has full column rank. The non-singular matrices lows A⇤i = A 1 Bi ⇤1 ⌦ A Bi⇤ = A 1 Bi ⇤i Bi0 A ⌦A 1B s Ug C AS (9) are defined as fol- 1 10 ⌦A 1 . A necessary condition for identification is that sg (g + 1) /2 p, where p = pA + pB + p⇤ represents the number of free parameters in the A, Bi , and ⇤i matrices, with i = 1, . . . , s. Proof. The proof of Proposition 1 is discussed in the Appendix A. Remark 2. When all Bi matrices are restricted to be unit diagonal, as already said, the model in Eq.s (1)-(2) can be reconciled with the Lanne and Lütkepohl’s (2008) approach. Using a well known result of matrix algebra in which two symmetric and positive definite matrices can be simultaneously diagonalized by means of common squared matrices and specific diagonal matrices, they show that simply exploiting the presence of two or more levels of volatility is sufficient for the structural parameters (the A matrix) to be identified (without the need of parameters restrictions, as instead in the well-known Cholesky triangularization). However, considering the necessary order condition in our Proposition 1, as well as the discussion in Lanne et al (2010, page 124), simultaneous diagonalization discussed above is exact only for s = 2 volatility regimes, while for more than two regimes 7 Any other multivariate stochastic variable univocally defined by the first two moments will provide the same results in terms of identification. 8 it is not necessarily possible. In other words, the model is exactly identified for s = 2, but overidentified for s 2. If a hypothetical LR test for such overidentifying restrictions would reject the null, the Lanne and Lütkepohl’s specification provides no alternatives. The heteroskedastic SVAR model described in Eq. (1)-(2), introducing the Bi parameters, fills this gap. The more complicated structure of the model, however, necessitates specific identification rules, provided in the previous Proposition 1.⌅ In practical applications, the necessary and sufficient condition in Eq. (9) can be numerically checked, as suggested in Giannini (1992), using random numbers for the three vectors A , B , and ⇤ such that the restrictions in Eq. (6) hold8 . III The European Debt Crisis This empirical analysis aims to shed light on the relationships between sovereign bond yields for some highly indebted EU countries. The data refer to 10-year bond maturity yield spreads between the so called ‘PIIGS’ countries (Portugal, Italy, Ireland, Greece, and Spain) versus Germany, used as benchmark, since German bonds have maintained their benchmark status and have continued to display lower yields even during both the financial and debt crises. We consider weekly observations over the period January 2005 - March 2014. All the series come from Datastream. The investigated period covers many interesting events characterizing the recent European and world-wide history, such as the global financial crises in 2007 and 2008, the 2008-2009 Spanish financial crisis, the great fear for the Greece default in 2010. All these events have led instabilities and tensions on the financial markets, which raised the problem of high public deficits and debt sustainability for the EU member states. Furthermore, given the strong interconnections between the markets, financial shocks in one country are likely propagated to other markets. Moreover, following Forbes and Rigobon (2002), Dungey et al (2010,2015) and Caporin et al (2013), such mechanisms of propagation are di↵erent during tranquil or turbulent periods. It becomes fundamental, thus, to distinguish between a) the “natural” interconnections between financial markets, that we indicate as interdependence, from b) the propagation of financial crises hitting one or more countries, that constitutes the pure or shift contagion phenomenon. As thoroughly discussed in the paper, such distinction, from an econometric point of view, leads to two serious problems of identification: The distinction between contagion and interdependence from one side, and the possible double causality between the two (or more) markets investigated. If the trend of market A is important in explaining the trend of market B, it could be possible that also the contrary holds. This clearly conflicts with the traditional theory of identification in simultaneous equation systems and SVARs9 . The model we have developed in this paper starts from the idea that the heteroskedasticity present in the data can provide new information to solve the identification problem. On the other hand, as we will discuss here below, the presence of di↵erent clusters of volatility cannot be excluded given the financial pressures characterizing the markets in the investigated sample. The model in Eq.s (1)-(2), and all the related results for identification, reveal to be well 8 A Gauss 13.0 package for checking for identification and estimating the unknown parameters of the heteroskedastic SVAR model developed in this paper can be obtained from the author upon request. 9 The problem has been circumvented by Favero and Giavazzi (2002) by imposing restrictions on the dynamic part of the model, leading the contemporaneous relationships unrestricted. 9 suited for distinguishing among interdependence and contagion, measured by the A and Bi matrices respectively. III.1 Stylized facts and historical events In Figure 1 we show the interest rates (left panel) and spreads (right panel) series for the sample period. From both graphs it emerges that the first years of the sample, at least up to the first signals of the global financial crisis, i.e. the collapse of the U.S. housing bubble and the consequent rise in interest rates in the second half of 2007, the interest rates for all EU countries followed practically the same almost constant trend. Since that period, and up to the almost overall recognized end of the global financial crisis in the late 2008, the EU interest rates started to rise and highlighted positive spreads with respect to their benchmark, the German Bund. At the end of the global crisis, such di↵erentials are in the order of 3 percent for Greece and Ireland, and 1.5 percent for Italy, Spain and Portugal. During the 2009 a moderate realignment appeared, but the situation became critical since the beginning of 2010, when the financial crisis turned into an even more dangerous debt crisis. Such debt crisis was mostly centered on events in Greece, where there was concern about the rising cost of financing government debt. The global financial crisis, however, had contributed to transform other EU countries into fertile ground for financial, economic and social instabilities to occur. Such weak economic and financial conditions acted as a trigger for the rise in the interest rates di↵erentials realized in the markets since the beginning of 2010. Idiosyncratic policy interventions pursued by the National Governments, associated to wider rescue remedies proposed by the EU and IMF, seem to have only moderate and transitory e↵ects on the situation of the financial markets, that up to the end of the sample continue to register incredibly high spreads with respect to Germany, leading to serious problems of sustainability of the public debt for those countries. The objectives of this section are twofold: First, we want to estimate the simultaneous relationships between the interest rates of these countries measured by the A matrix in our general model specification. The complicated economic and financial interconnections between all these countries do not allow to follow any economic theoretical framework, suggesting thus to estimate such matrix unrestrictedly. Second, the global and idiosyncratic financial crises suggest to estimate di↵erent mechanisms of propagation of shocks in periods of high volatility regimes as described by the Bi matrices in our formulation. In Table 1 we report the di↵erent covariance and correlation matrices among the spreads over di↵erent horizons in the sample. Among the di↵erent sub periods described above, very di↵erent values for the variances and covariances among the spreads clearly emerge. Apart for the first period, characterized by stable interest rates and spreads, for all the other periods the correlations between the spreads are high and generally above 0.9. 10 III.2 Interdependence and contagion We consider that the structural form of the model is given as follows 0 B B B AB B @ spt irt ptt grt itt 1 get get get get get 0 C B C B C B C = c+ (L) B C B A @ spt irt ptt grt itt get get get get get 1 C C C C+⇥ (L) C A V ixxt 1 Baat 1 Aaat 1 ! +Bi 0 B B B (t 2 Ti ) B B @ (10) where spt get , irt get , ptt get , grt get , and itt get are the interest rate spreads for Spain, Ireland, Portugal, Greece, and Italy, respectively. Baat Aaat is the spread between BAA and AAA corporate bonds and V ixxt measures market expectations of near term volatility conveyed by stock index option prices. Both indicators represent exogenous variables that could play a relevant role in the explanation of EU spreads. (L) and ⇥ (L) are two matrix polynomials in the lag operator L, while c is a vector of constant terms.10 A and Bi , i = 1, . . . , s are the matrices of interest and measure the interdependence and contagion relationships, respectively. The "’s are the idiosyncratic shocks, and are assumed to be uncorrelated and with regime-specific variances given by ⇤i , i = 1, . . . , s. As before, Ti collects all the time periods such that regime i is in place, and (·) is the indicator function. The reduced form of the model is trivially obtained by premultiplying both sides of Eq. (10) by the invertible matrix A 0 B B B B B @ spt irt ptt grt itt get get get get get 1 C C C C=A C A 1 c+A 1 0 B B B (L) B B @ spt irt ptt grt itt get get get get get 1 C C C C+A C A 1 ⇥ (L) V ixxt 1 Baat 1 Aaat 1 ! + ut (11) where the reduced-form residuals ut satisfy 0 B B B AB B @ usp t uir t upt t ugr t uit t 1 0 C B C B C B C = Bi (t 2 Ti ) B C B A @ "sp t "ir t "pt t "gr t "it t 1 C C C C C A , E "t "0t = ⇤i for t 2 Ti (12) that continue to share the same interdependence-contagion relationships as the original model in Eq. (10). Without any constraint on the parameters of the predetermined variables, maximizing the likelihood for Eq. (10) is equivalent to maximizing the concentrated likelihood in Eq. (12). 10 Originally, other explanatory variables, like US and EU stock price indices, Euro/US Dollar exchange rate, EU and US short term interest rate, have been included as potential exogenous regressors. However, the explanatory power was so poor that an F test strongly suggested to exclude all these variables from the analysis. 11 "sp t "ir t "pt t "gr t "it t 1 C C C C C A The reduced form and the structural breaks The reduced form in Eq. (11) can be seen as a standard VAR model. The residuals ut depend on the structural matrices A, Bi and ⇤i , but also on the volatility regime dates. The first point, thus, concerns the determination of the regimes. The recent events concerning the global financial crisis and the EU debt crisis provide a natural framework to define the regimes. As mentioned before, these events have been associated with large and persistent increases in volatility. Since June 2007 the five countries experienced global and idiosyncratic shocks that allow us to distinguish, country by country, tranquil from turbulent periods. In Spain, the first and strong signals of instabilities appeared even before the ‘official’ start of the global financial crisis. During the second half of 2007, when the real estate bubble burst, the crisis immediately overcame the whole banking system that, although credited as one of the most solid and best equipped among all Western economies to cope with the worldwide liquidity crisis, strongly relaxed his strict requirements from intending borrowers during the housing bubble, o↵ering up to 50-year mortgages. As for the Spanish case, the Irish crisis was triggered by the ‘terrible’ mix of a real estate bubble from one side, and over-exposure of many large banks that financed the property market, from the other side. The situation for the banking sector became critical in September 2007, with the explosion of the global financial crisis. The recent historical events were substantially di↵erent for Greek and Portugal. Given the limited exposure of these countries with respect to international financial markets, they were only marginally touched by the global financial crisis. The Portuguese financial crisis was mainly an economic and political crisis and started during the first weeks of 2010. In Greece, instead, in only few days the situation became completely out of control. Facing the growing increase of the public debt, on April 23 the Greek government asks an initial loan of 45 billion euro to the EU and IMF to cover its financial needs for the remaining part of 2010. Only few days later Standard & Poor’s decided to relegate the sovereign debt rating to ‘junk’. The Italian case is completely di↵erent. As is well-known, Italy has the largest Debt/GDP ratio amongst the major European countries, around 115% at the end of 2010. However, Italy is not growing it faster than its neighbors. The government deficit is small, and the country has a best in class primary balance. Nevertheless, unstable and weak political conditions, as well as the uncertainty due to the large amount of debt that has to be rolled over each year, by August 2011 the spread between Italian ten-year bonds and their German counterparts reached alarming levels, pushing ECB President and Bank of Italy Governor to writing a joint letter to Italian Prime Minister calling for ‘immediate and bold’ measures to promote growth. The combination of these events indicates approximately s = 3 di↵erent volatility regimes: quiet until mid 2007, crises in Spain and Ireland until early 2010, and then crisis everywhere. More precisely, we take as break dates a) June 2007, that is generally taken as the first signal of the crisis in Spain and b) the end of January 2010, when the Portuguese government announces strong measures to reduce the budget deficit, raised up to a worrisome 9.4%. These dates are clearly indicative, although warmly suggested by the hystorical events and by the data reported in Figure 1. A robustness analysis, however, will be conducted in order to confirm the main empirical findings. Although the attention is mainly paid on the di↵erent volatility regimes, a special atten12 tion must be paid on the stability of the dynamics of the VAR. A set of statistical tests will be thus performed in order to verify, firstly, whether the break dates discussed before are e↵ectively structural breaks, and secondly whether such breaks are confined to the volatility of the residuals or involve the dynamics too. We first consider the VAR model without any break. A joint analysis of information criteria and specification tests on the residuals suggests to include 6 lags for both the ⇥ and polynomials. We then account for the structural breaks on the covariance matrices only. A (quasi)LR test for the null that there are no breaks against the alternative of two breaks on the covariance matrices can be given by LR = 2 [372.51 (1219.81 + 668.51 213.45)] = 2604.71, which suggests to strongly reject the null with a p value = 0.000 (taken from a 2(30) distribution). Moreover, when considering a completely unrestricted model, i.e. di↵erent dynamics and di↵erent covariance matrices, and compare it with a model with constant dynamics but di↵erent covariance matrices, the (quasi-)LR test becomes LR = 2 [1674.87 2806.32] = 2262.89 that continues to reject the null with a p value = 0.000 (taken from a 2(310) distribution). We thus find formal support that the two breaks involve both the dynamics and the volatility of the VAR model. The analysis of the structural form of the model, thus, will be focused on regime-specific VAR models, each of which written as in Eq.s (1)-(2). In Figure 2 (middle panel) we report the residuals of the estimated reduced forms, as well as the fitted and actual series of the spreads11 (left panel). In the right panel, instead, we report the absolute values for the reduced form residuals, which clearly highlight the presence of di↵erent volatility clusters. The structural form The structural form of the model in Eq.s (10)-(12) does not meet the identifying conditions reported in Proposition 1. More precisely, focusing on the concentrated version in Eq. (12), the parameters to estimate are 20 for the A matrix (we impose unit values on the main diagonal), 75 for the Bi matrices and 15 for the diagonal ⇤i matrices, i = 1, . . . , 3. The number of empirical moments provided by the covariance matrices of the residuals ⌃i , i = 1 . . . 3, are instead 3g (g + 1) /2 = 45. The necessary condition in Proposition 1 states that 20 + 75 + 15 45 = 65 further restrictions must be imposed. First of all, given the nature of the first regime, characterized by the absence of significant turbulences on the financial markets, we suppose that the transmission of shocks takes place only through the interdependence among the markets. The first set of restrictions, thus, is B1 = I5 (25 restrictions). The other two regimes, instead, are characterized by strong turmoils that, as largely discussed above, hit the financial markets with a well determined order; in sequence, Spain, Ireland, Portugal, Greece and, finally, Italy. This series of historical events allows to restrict the B2 and B3 matrices to be lower triangular (with unit values on the main diagonal), where the order of the variables respects the one just mentioned (which corresponds to what indicated in the representations in Eq.s (10)-(12)). 11 As said above, the standard steps for the correct specification of the VAR models in each regime suggest to include 6 lags for both the ⇥ and polynomials. The included dynamics, however, reveals to be not sufficient for cleaning the residuals in terms of departure from normality, especially for the excess of kurtosis. Increasing the number of lags does not help to solve the problem. All estimates (and inference), thus, should be referred to ‘quasi’-ML (and ‘quasi’-LR tests). As expected, the residuals show strong signals of heteroskedasticity, that justifies the “identification through heteroskedasticity” strategy pursued in the paper. All results are available upon request. 13 Moreover, we suppose that B2 and B3 do not change across the two regimes, i.e. B2 = B3 . The diagonal covariance matrices ⇤1 , ⇤2 and ⇤3 , instead, are left free to vary across the three volatility regimes. This set of restrictions allows the model to meet both the order (necessary) and rank (necessary and sufficient) conditions discussed in Proposition 1. More precisely, the model is exactly identified, with 45 parameters to estimate, and 45 empirical moments. Estimated results The estimated parameters, with associated standard errors, are reported in Table 4. Column (1) reports the estimates (and related standard errors) of A, Bi and ⇤i where some highly insignificant coefficients are set to zero. Interestingly, this new procedure allows to consistently estimate the parameters of the contemporaneous relationships among the endogenous variables (the A matrix) without imposing exclusion restrictions as generally required in the traditional approach for the simultaneous equation models and SVARs. Di↵erently to standard SVARs, the proposed specification allows the identification and estimation of the elements in the Bi matrices, accounting for the propagation of the structural shocks during turbulent periods. The (quasi-)LR test statistic, with associated p-value, for such overidentifying restrictions, is reported in the last row of the table. The test suggests to not reject the null hypotheses for all standard significant levels. Interestingly, the test is not simply a test for the overidentifying restrictions, but represents a test for the entire structure of the model, too. In other words, the test does not reject the lower-triangularity and equivalence of B2 and B3 . For a more comprehensible reading of the results we show, in the following equation, the estimated A and Bi parameters in a matrix notation, as reported in Table 4: 0 B B B B B @ 1 1.294 1.141 1 0.226 0.102 0.109 0 0.585 0.084 0.331 0.215 1 0.345 0.558 0 B B B +B B @ 0 B B B +B B @ 0.046 0.025 0.454 1 0 1.760 0.949 0.441 1.206 1 10 CB CB CB CB CB A@ usp t uir t upt t ugr t uit t 1 0 0.380 1 0.119 0 0.156 0 0 0.763 0 0 0 0 1 0 0.959 1 0 0.260 0 0 0 0 1 1 0 0.380 1 0.119 0 0.156 0 0 0.763 0 0 0 0 1 0 0.959 1 0 0.260 0 0 0 0 1 1 C C C C = I5 (t 2 T1 ) + C A 1 C C C C (t 2 T2 ) + C A 1 C C C C (t 2 T3 ) C A 0 B B B B B @ (13) "sp t "ir t "pt t "gr t "it t 1 C C C C C A where the three covariance matrices of the structural shocks, together with those of the residuals of the VAR model, are reported in Table 2. The interpretation of the results is as follows. The first equation, for example, can be 14 read as an equation for the Spanish spread, that depends on the other contemporaneous spreads and the idiosyncratic structural shock "sp t , that with di↵erent levels of volatility, hits the Spanish spread during the three regimes. The second equation, instead, is devoted to explain the Irish spread and, other than depending from the other spreads and the idiosyncratic structural shock "ir t , during turbulent periods (second and third regimes), also depends on the Spanish structural shock "sp t , through the 0.380 coefficient. This evidence highlights that during turmoils there is a further channel for the transmission of shocks that, given the positive sign of the coefficient, can be interpreted as contagion (from Spain to Ireland). The other equations can be interpreted accordingly. The first comment highlights that there are bi-directional interdependent relations among all the spreads, as indicated by the full structure of the A matrix. This result, allowed by the heteroskedasticity present in the data, confirms that it would have been dangerous to impose identifying restrictions on the A matrix. Unexpectedly, some of the coefficients present a positive sign, indicating that the referring spread enters negatively in that specific equation. In particular, two of these coefficients are surprisingly high (Irish spread in the Spanish equation and Italian spread in the Irish equation). However, looking at the results in Table 4, these coefficients are imprecisely estimated and, as shown in the robustness checks in Section III.3, dramatically reduce when using the first di↵erences of the spreads instead of the levels. As can be seen from the coefficients shown in Eq. (13), during the second and third regimes there are di↵erent episodes of contagion. However, one of the coefficient in the B2 and B3 parameters merits a special attention. Overall, the Greek spread depends, among others, negatively from the Portuguese spread (interdependence). Furthermore, during periods of crisis, an unexpected open of the Portuguese spread given by a positive "pt t shock, negatively transmits to the Greek spread through the 0.959 coefficient. During turbulent periods, the negative impact of the Portuguese spread on the Greek one is even reinforced. Due to identification issues, the imposed restrictions of a common transmission structure during the global financial crisis and during the EU debt one (B2 = B3 ) is not rejected by the data. In fact, when imposing some zero restrictions on A, B2 and B3 , obtaining thus degrees of freedom for possible LR or Wald tests, common parameters in B2 and B3 are strongly supported by the data (see the LR test in the last row of Table 4, columns (1)-(3), according to the di↵erent specification of the VAR model). This result is in line with Caporin et al (2013), who find that when there is a change in the propagation mechanism, this appended with the burst of the global financial crisis, and not when passing from the global financial crisis to the debt one. Although the transmission mechanism does not change during the global and debt crises, the volatility of the shocks is much larger during the latter period, as shown by the extremely di↵erent ⇤2 and ⇤3 matrices. This justifies the much larger volatility of the spreads during the debt crisis with respect to the global financial one, as reported in Figure 1 and Figure 2. Overall, the previous results highlight that the di↵erent regimes are characterized by di↵erent transmission of shocks: through the A matrix during the quiet first regime, through the combination of the A and the Bi coefficients during turbulent periods. This result, obtained using the di↵erent volatility regimes featuring the data, is completely new in the literature of SVAR models. Lanne and Lütkepohl (2008), in generalizing the original Rigobon’s approach, consider di↵erent volatility regimes. However, as explained in the Remark 1 in Section II.1, they explain the regimes as di↵erent variances of the uncorrelated 15 structural shocks. In our model, this is given by considering ⇤1 6= ⇤2 6= ⇤3 , but restricting the Bi matrices as B1 = B2 = B3 = I5 . In other words, they consider the transmission of shocks to remain the same across regimes. As said before, the novelty in our approach is to consider possible di↵erences in the transmission of shocks. The Lanne and Lütkephol’s specification is exactly identified for s = 2 volatility regimes, while becomes overidentified for more than two regimes. In particular for s = 3 regimes, as in our empirical analysis, we have g (g 1) /2 degrees of freedom for a formal (quasi-)LR test on the structure of the model. Estimating our specification with the Lanne and Lütkephol’s restrictions we obtain a log-likelihood value equal to 2704.35, that when compared to the log-likelihood of the unrestricted model (with cointegration restrictions) gives LR = 2 [2704.35 2733.10] = 57.49 that is strongly rejected with a p value = 0.000 (taken from a 2(10) distribution).12 The transmission of shocks, in our empirical application is much more complicated than what described by the Lanne and Lütkephol’s model. III.3 Robustness In this section we report a set of robustness checks. First, we consider alternative specifications of the model and di↵erent data. Second, we check the robustness of the results versus the uncertainty associated to the break dates. The main results presented in Eq. (13) and in Table 4 - column (1) - are obtained by considering the levels of the spreads. In fact, if the VARs are correctly specified, Sims et al. (1990) suggest that the parameters of the reduced form, and thus the residuals, can be consistently estimated even in the case of non-stationary time series. In Table 4, column (2), instead, we report the structural parameters for the model estimated with the first di↵erences of the spreads, instead of the levels. The results are completely in line with those presented for the main specification. A related point, concerns the presence of unit roots and, eventually, cointegration among the investigated spreads. The investigation for the presence of structural breaks has shown that the analysis should be restricted within each regime. In Table 3 we report the results of the unit root and cointegration analysis for each regime. The Johansen trace test provides evidence of non-stationarity and, more precisely, suggests r = 1 cointegrating relation in the first and second regimes13 , and r = 2 in the third. The results of the estimated A and B matrices are reported in Table 4 - column (3) - and show that accounting for unit roots and cointegration does not substantially alter those obtained in the previous specifications, i.e. considering the levels of the spreads or their growth rates. The last column (4) of Table 4, as already said, reports the estimated coefficients when the Bi matrices are all set to the identity matrix, as in the Lanne and Lütkepohl’s (2008) specification. Important, the results are strongly rejected by the LR test (bottom part of the column) with a p-value practically equal to zero. The previous results have been obtained by using interest rate spreads. The same analysis has been repeated by using weekly bond returns. Once transformed to excess 12 The complete set of results can be obtained from the author upon request. In both the first and third regimes the cointegration analysis has been performed by considering a restricted constant as deterministic term. For the second regime, instead, given the increasing path of all the spreads emerging from Figure 1 (right panel) a restricted trend seemed preferable. Furthermore, looking at the trace test reported in Table 3, it seems to suggest r = 3, and as a consequence 2 = 5 3 unit roots in the system. When imposing these restrictions, however, the system continues to be characterized by two further roots practically equal to one. The most reasonable solution, thus, is to impose r = 1 (and thus four unit roots) with a restricted deterministic trend. From here onward, we will include a (restricted) deterministic trend in the VAR model for the second regime. 13 16 returns, the new series are almost proportional to the first di↵erences of the interest rate spreads (e.g., the correlation between the excess return for Spanish bonds and the first di↵erence of the interest rate spread (spt get ) is 0.98). The structural breaks for the reduced form VAR model are strongly confirmed and the estimated A and Bi matrices are practically identical.14 As already discussed in the previous sections, the way the breaks are detected might have an influence on the estimation of the parameters. Di↵erent strategies could be used in order to endogenously determine the breaks, e.g. through Markov switching models (see Lanne et al, 2010, for an application to heteroskedastic SVARs) or the general framework proposed by Qu and Perron (2007). However, given the consolidated sequence of events characterizing the investigated period, we alternatively focus on whether the results are robust to small or moderate variations of the break dates. We have thus performed a set of simulations in which the break dates are randomly generated around the original breaks (those used in the main empirical analysis). More precisely we use a uniform distribution to generate breaks up to 4 or 8 weeks before or after the original breaks. For each new break date we re-estimate the model and perform the LR tests both for the plausibility of the break and for overidentifying restrictions, in order to compare the new results with the main empirical findings. The structural form, for simplicity, refers to a VAR model in levels, only. The results are reported in Table 5, for 1000 replications for each of the two window widths. In column (1), for facilitating the comparison, we report the corresponding results obtained in Table 4, column (3). In columns (2) and (3) we show the estimated coefficients for the 8-16 weeks window width, respectively. Concerning the new break dates, for both windows widths, the LR test for the constancy of the reduced form parameters (both the dynamics and the covariance matrices) always rejects the null. Concerning the overidentifying restrictions imposed in the main analysis, they are rejected only once and five times for the two window widths, respectively. For each of the two simulation exercises we report the median, the mean, the first decile and the ninth decile. The results are clearly in line with those obtained in the main analysis. Overall, the simulation exercises confirm the presence of the two breaks and, moreover, the results are robust to possible misspecification of the break dates. IV Conclusion This paper o↵ers two main contributions in the discussion of contagion: methodological and empirical. Firstly, we have presented a theoretical framework for distinguishing between interdependence and contagion in the transmission of financial shocks. In particular, we have proposed a new specification of SVAR models that explicitly allows for di↵erent states of volatility. The identification problem in the structural form of the model has been solved by using the information coming from the di↵erent volatility regimes, under the assumption that some of the structural parameters remain stable over time, in the spirit of the “identification through heteroskedasticity” framework. The specification adopted is well suited for distinguishing between interdependence and contagion in an environment in which the investigated countries can behave alternatively as originating or a↵ected actors. The endogeneity problem, thus, generally by-passed in the literature (where a specific financial crisis naturally selects the originating country, leaving 14 The results, not reported here for saving space, are available from the author upon request. 17 all the others as simply a↵ected), is here solved by using the heteroskedastic structural VAR model discussed in the paper. Secondly, we have proposed an empirical analysis focusing on the transmission of financial shocks within five highly indebted EU countries; Spain, Ireland, Portugal, Greece and Italy. The particular specification of the model provides a useful tool for modeling the higher volatility of the interest rates on sovereign bonds observed during the recent turbulences on the financial markets all over the world. The results highlight that a) there are two structural breaks, a↵ecting both the reduced form parameters and the covariance matrix of the residuals, b) the propagation of financial shocks is di↵erent between tranquil and turbulent periods, although it does not change across global financial crisis and debt crisis and c) the volatility of the shocks is much larger during the debt crisis, compared to that of the global financial crisis. These findings are robust to di↵erent specification of the VAR model, di↵erent data and possible misspecification of the break dates. 18 References Amisano, G. and Giannini, C. (1997), Topics in Structural VAR Econometrics, 2nd edn, Springer, Berlin. Arezki, R., Candelon, B. and Sy, A.N.R. (2011), Sovereign Rating News and Financial Markets Spillovers: Evidence from the European Debt Crisis, IMF Working Paper 11/68. Bacchiocchi, E. and Bevilacqua, M. 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(14), for i = 1, . . . , s, gives A 1 dAA 1 Bi ⇤i Bi0 A 10 A +A 1 1 dBi ⇤i Bi0 A Bi ⇤i dBi0 A 10 10 +A +A 1 1 Bi d⇤i Bi0 A Bi ⇤i Bi0 A 10 10 dA0 A + 10 = 0 (15) Using the property vec (ABC) = (C 0 ⌦ A) vec B the system of equations can be written ✓ ◆ ✓ ◆ ✓ ◆ 1 0 10 1 1 1 1 1 A Bi ⇤i Bi A ⌦ A vec dA + A Bi ⇤i ⌦ A vec dBi + A Bi ⌦ A Bi vec d⇤i ✓ ◆ ✓ ◆ 1 1 1 1 0 10 + A ⌦ A Bi ⇤i Kg vec dBi A ⌦ A Bi ⇤i Bi A Kg vec dA = 0 that, using the properties of the commutation matrix Kg , becomes ✓ 2Ng A 1 Bi ⇤i Bi0 A 10 ⌦A 1 ◆ ✓ 1 1 ◆ vec dA + 2Ng A Bi ⇤i ⌦ A vec dBi + ✓ ◆ A 1 Bi ⌦ A 1 Bi Ug dw (⇤i ) = 0 (16) where Ug , already defined above, is such that Ug0 w (M ) = vec M with w (M ) = (m11 , m22 , . . . , mnn )0 . The Jacobian and the necessary and sufficient condition in Eq. (9) immediately follow. The necessary-only condition in Proposition 1, instead, refers to the number of free parameters to be estimated (p) with respect to the number of empirical moments provided by ⌃i , i = 1, . . . , s. This is easily proved by observing that the number of empirical moments is given by sg (g + 1) /2. ⌅ 22 B Appendix: Estimation and Inference In this appendix we turn to the problem of estimating the heteroskedastic SVAR model in Eq.s (1)-(2), assuming that some sufficient condition for identification is satisfied. We propose a Full-Information Maximum Likelihood (FIML) estimator that is based on the maximization of the likelihood function of the structural form of the model. For the specific case of three regimes used in the empirical analysis, the concentrated log-likelihood function can be written as: lT (✓) = T1 log |A|2 2 T1 T2 T1 2 log |⇤1 | log A 1 B2 log |⇤1 | 2 2 2 ✓ ◆ T3 T3 T1 2 10 1 1 ˆ 1 0 log A B3 log |⇤3 | tr A B1 ⇤1 B1 A⌃1 2 2 2 ✓ ◆ ✓ ◆ T2 T3 10 1 1 ˆ 10 1 1 ˆ 0 0 tr A B2 ⇤2 B2 A⌃2 tr A B3 ⇤3 B3 A⌃1 2 2 (17) ˆ i is the estimated covariance matrix of the VAR residuals in the i-th regime. Maxwhere ⌃ imizing the log-likelihood function in Eq. (17) provides ML estimators for the structural parameters A, Bi and ⇤i , i = 1 . . . 3. However, if the actual distribution of the "t ’s is non-normal, as it seems to be in our empirical application, the estimators are of course quasi -ML, and the same holds for the related inference. C Appendix: Tables and Figures Table 1: Covariances and Correlations across di↵erent sub periods First regime 16/02/200530/05/2007 T1 = 126 Second regime 06/06/200720/01/2010 T2 = 138 Third regime 27/01/20105/3/14 T3 = 215 sp-ge 0.0006 0.0000 0.0004 -0.0003 -0.0002 0.0849 0.2119 0.1019 0.2229 0.1037 1.3517 0.8012 2.5103 7.0838 1.2422 ir-ge 0.0000 0.0048 0.0020 0.0024 0.0019 0.2119 0.6424 0.2667 0.6020 0.2517 0.8012 4.2626 4.0656 10.1390 0.7882 pt-ge 0.0004 0.0020 0.0050 0.0033 0.0028 0.1019 0.2667 0.1327 0.2755 0.1276 2.5103 4.0656 8.6490 23.3689 2.8558 gr-ge -0.0003 0.0024 0.0033 0.0048 0.0035 0.2229 0.6020 0.2755 0.6617 0.2641 7.0838 10.1390 23.3689 78.2626 8.3973 23 it-ge -0.0002 0.0019 0.0028 0.0035 0.0029 0.1037 0.2517 0.1276 0.2641 0.1363 1.2422 0.7882 2.8558 8.3973 1.3592 sp-ge 1 0.0255 0.2462 -0.1541 -0.1579 1 0.9077 0.9599 0.9406 0.9642 1 0.3338 0.7342 0.6887 0.9164 ir-ge 0.0255 1 0.4093 0.5047 0.5211 0.9077 1 0.9135 0.9233 0.8506 0.3338 1 0.6696 0.5551 0.3275 pt-ge 0.2462 0.4093 1 0.6654 0.7317 0.9599 0.9135 1 0.9296 0.9485 0.7342 0.6696 1 0.8982 0.8329 gr-ge -0.1541 0.5047 0.6654 1 0.9267 0.9406 0.9233 0.9296 1 0.8794 0.6887 0.5551 0.8982 1 0.8142 it-ge -0.1579 0.5211 0.7317 0.9267 1 0.9642 0.8506 0.9485 0.8794 1 0.9164 0.3275 0.8329 0.8142 1 Table 2: Estimated Covariance matrices: Reduced form (left panel) and Structural form (right panel). 0.0002 0.0000 0.0000 0.0000 0.0000 0.0000 0.0004 0.0000 0.0000 0.0000 0.0013 0.0017 0.0014 0.0016 0.0013 0.0017 0.0069 0.0027 0.0028 0.0024 0.0461 0.0355 0.0329 0.0883 0.0366 0.0355 0.1044 0.0699 0.1062 0.0307 ˆ1 ⌃ 0.0000 0.0000 0.0001 0.0000 0.0000 ˆ2 ⌃ 0.0014 0.0027 0.0027 0.0030 0.0021 ˆ3 ⌃ 0.0329 0.0699 0.1667 0.1489 0.0318 0.0000 0.0000 0.0000 0.0002 0.0001 0.0000 0.0000 0.0000 0.0001 0.0001 0.0015 0 0 0 0 0 0.0009 0 0 0 0.0016 0.0028 0.0030 0.0074 0.0024 0.0013 0.0024 0.0021 0.0024 0.0026 0.0105 0 0 0 0 0 0.0075 0 0 0 0.0883 0.1062 0.1489 0.8668 0.0779 0.0366 0.0307 0.0318 0.0779 0.0445 0.1755 0 0 0 0 0 0.0743 0 0 0 ˆ1 ⇤ 0 0 0.0002 0 0 ˆ2 ⇤ 0 0 0.0011 0 0 ˆ3 ⇤ 0 0 0.2197 0 0 0 0 0 0.0002 0 0 0 0 0 0.0002 0 0 0 0.005 0 0 0 0 0 0.0035 0 0 0 0.6553 0 0 0 0 0 0.1259 Table 3: Cointegration analysis (standard errors in parentheses). first regime 16/02/2005-30/05/2007 T1 = 120 Rank Trace test p-value 0 83.035 0.015 1 38.575 0.548 2 20.857 0.673 3 11.604 0.493 4 4.205 0.394 second regime 06/06/2007-20/01/2010 T2 = 138 Rank Trace test p-value 0 180.490 0.000 1 110.220 0.000 2 57.664 0.001 3 20.731 0.194 4 6.069 0.462 1 es-ge ir-ge pt-ge 1 0.337 es-ge 0 ir-ge (0.099) 0.225 pt-ge (0.041) gr-ge 0.570 gr-ge (0.043) it-ge 1 third regime 27/01/2010-05/03/2014 T3 = 215 Rank Trace test p-value 0 111.270 0.000 1 60.654 0.010 2 27.023 0.292 3 12.827 0.386 4 1.923 0.788 1 es-ge 1 0 0.054 ir-ge 0 0 0.345 pt-ge 0 gr-ge 0 (0.028) (0.098) 0.241 (0.027) it-ge 2 1 0.560 1 ( ) 0.398 (0.048) it-ge 1 0 (0.053) const 0.073 trend (0.021) es-ge ir-ge pt-ge gr-ge it-ge 2 (1) p-value ↵1 0.093 es-ge 0.539 ir-ge (0.242) (0.322) 0.561 (0.191) 0.325 (0.242) 0.434 0.001 const (0.000) ↵1 1.236 es-ge (0.184) 0.417 1.183 pt-ge (0.260) gr-ge 1.132 gr-ge (0.430) it-ge 0.763 (0.146) (0.256) 0.202 0.653 exactly identified 24 ↵1 0.070 (0.044) ir-ge (0.416) pt-ge 0.357 (0.466) 0.047 (0.066) 0.146 (0.084) 0.820 (0.191) it-ge 2 (5) p-value 0.010 (0.043) 9.402 0.094 4.280 (0.915) ↵2 0.021 (0.009) 0.003 (0.014) 0.047 (0.018) 0.128 (0.041) 0.026 (0.009) Table 4: FIML estimates of A, Bi and ⇤i . (1) VAR levels (2) VAR first di↵. (4) RigobonLanne-Lütkepohl param. SE -0.205 0.163 -0.229 0.075 0.027 0.071 0.371 0.070 -0.058 0.051 -0.035 0.039 -0.019 0.046 0.091 0.061 0.014 0.039 -0.284 0.060 0.168 0.130 0.195 0.067 -0.035 0.010 -0.014 0.025 -0.163 0.034 -0.121 0.030 -0.713 0.052 -0.545 0.165 -0.554 0.075 -0.914 0.131 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.018 0.001 0.021 0.001 0.013 0.001 0.013 0.001 0.010 0.001 0.028 0.002 0.065 0.004 0.028 0.002 0.074 0.005 0.069 0.007 0.121 0.006 0.259 0.014 0.367 0.019 0.898 0.048 0.299 0.028 SE param. SE param. SE 0.543 -0.668 0.269 -1.162 0.492 0.074 -0.296 0.081 -0.237 0.077 0.089 0.000 -0.087 0.083 0.108 0.637 0.122 0.634 0.118 0.881 0.450 0.202 1.402 0.837 0.066 0.140 0.070 0.127 0.065 0.000 0.000 0.083 0.000 0.063 0.079 0.261 -0.110 0.073 -0.362 0.252 0.065 -0.264 0.055 -0.196 0.066 0.159 0.000 0.359 0.138 0.149 0.444 0.117 0.519 0.148 0.040 -0.042 0.015 -0.057 0.047 0.031 -0.026 0.025 -0.039 0.030 0.115 -0.321 0.065 -0.426 0.090 0.000 0.000 0.668 -1.136 0.151 -1.816 0.647 0.594 0.474 0.259 1.190 0.594 0.148 -0.449 0.112 -0.474 0.125 0.166 -0.898 0.104 -1.150 0.141 0.215 0.544 0.103 0.351 0.194 0.078 0.279 0.098 0.140 0.082 0.126 0.000 0.061 0.091 0.000 0.000 0.099 0.083 0.000 0.000 0.000 0.180 0.599 0.137 0.849 0.166 0.128 -0.960 0.194 -0.916 0.158 0.000 0.000 0.080 0.218 0.059 0.255 0.075 0.016 0.021 0.003 0.039 0.016 0.008 0.022 0.002 0.030 0.008 0.001 0.014 0.001 0.014 0.001 0.001 0.014 0.001 0.014 0.001 0.002 -0.013 0.002 0.014 0.002 0.052 0.043 0.009 0.102 0.053 0.013 0.072 0.006 0.087 0.017 0.005 0.029 0.003 0.033 0.004 0.006 0.066 0.005 0.070 0.006 0.010 0.072 0.009 0.059 0.009 0.217 0.194 0.042 0.419 0.214 0.047 0.240 0.020 0.273 0.054 0.066 0.444 0.037 0.469 0.052 0.063 0.803 0.063 0.810 0.062 0.054 0.378 0.044 0.355 0.050 LR test for over-identifying restrictions 2 2 2 2 LR 1.255 3.839 1.257 57.485 6 = 6 = 6 = 10 = (p-value) (0.974) (0.922) (0.974) (0.000) Note: The generic ijj . parameter represents the squared root of the variance of the structural shock in equation j for the i-th regime. A21 A31 A41 A51 A12 A32 A42 A52 A13 A23 A43 A53 A14 A24 A34 A54 A15 A25 A35 A45 B21 B31 B41 B51 B32 B42 B52 B43 B53 B54 ⇤111 ⇤221 ⇤331 ⇤441 ⇤551 ⇤112 ⇤222 ⇤332 ⇤442 ⇤552 ⇤113 ⇤223 ⇤333 ⇤443 ⇤553 param. -1.141 -0.226 -0.109 0.585 1.294 0.102 0.000 0.084 -0.331 -0.215 0.345 0.558 -0.046 -0.025 -0.454 0.000 -1.760 0.949 -0.441 -1.206 0.380 0.119 0.156 0.000 0.000 0.000 0.763 -0.959 0.000 0.260 0.036 0.028 0.014 0.014 0.013 0.089 0.067 0.033 0.061 0.071 0.383 0.243 0.483 0.757 0.379 (3) — Cointegrated VAR 25 Table 5: Simulation results for the robustness towards the break dates. (1) (2) median ninth mean first median ninth mean decile decile decile A21 -1.120 -0.995 -1.334 -2.284 -1.120 -0.977 -1.439 A31 -0.226 -0.208 -0.239 -0.281 -0.239 -0.213 -0.233 A41 -0.110 -0.083 -0.106 -0.155 -0.119 -0.084 -0.134 A51 0.607 0.631 0.609 0.588 0.612 0.665 0.614 A12 1.261 2.676 1.780 1.089 1.269 3.964 2.156 A32 0.108 0.117 0.107 0.100 0.115 0.132 0.125 A52 0.087 0.101 0.088 0.071 0.085 0.102 0.084 A13 -0.324 -0.266 -0.458 -1.062 -0.326 -0.229 -0.540 A23 -0.196 -0.175 -0.195 -0.216 -0.196 -0.158 -0.200 A43 0.343 0.356 0.338 0.293 0.355 0.528 0.376 A53 0.568 0.712 0.585 0.514 0.580 0.684 0.615 A14 -0.048 -0.031 -0.065 -0.185 -0.049 -0.030 -0.089 A24 -0.031 -0.023 -0.032 -0.041 -0.033 -0.026 -0.065 A34 -0.460 -0.379 -0.452 -0.584 -0.492 -0.392 -0.511 A15 -1.761 -1.676 -2.058 -3.180 -1.856 -1.674 -2.239 A25 0.928 1.782 1.253 0.843 0.972 2.508 1.426 A35 -0.450 -0.426 -0.453 -0.501 -0.434 -0.269 -0.385 A45 -1.211 -1.129 -1.199 -1.319 -1.223 -1.126 -1.200 B21 0.384 0.414 0.314 0.111 0.362 0.413 0.288 B31 0.106 0.184 0.113 0.056 0.111 0.187 0.118 B41 0.139 0.236 0.127 0.011 0.136 0.267 0.125 B52 0.770 0.923 0.778 0.549 0.769 0.942 0.770 B43 -0.963 -0.915 -0.956 -0.981 -0.954 -0.893 -0.937 B54 0.266 0.304 0.268 0.245 0.279 0.314 0.277 1 0.035 0.062 0.045 0.032 0.036 0.087 0.052 11 1 0.028 0.039 0.032 0.026 0.028 0.050 0.034 22 1 0.014 0.014 0.014 0.013 0.014 0.015 0.013 33 1 0.014 0.014 0.014 0.014 0.014 0.015 0.014 44 1 0.013 0.014 0.013 0.013 0.013 0.015 0.013 55 2 0.088 0.169 0.116 0.079 0.092 0.218 0.134 11 2 0.069 0.084 0.074 0.067 0.075 0.099 0.081 22 2 0.033 0.053 0.037 0.029 0.034 0.058 0.040 33 2 0.061 0.068 0.061 0.044 0.061 0.079 0.063 44 2 0.071 0.079 0.070 0.063 0.068 0.078 0.070 55 3 0.378 0.724 0.503 0.338 0.379 1.039 0.602 11 3 0.247 0.317 0.273 0.241 0.259 0.389 0.290 22 3 0.488 0.522 0.484 0.451 0.510 0.559 0.500 33 3 0.754 0.785 0.757 0.722 0.747 0.781 0.741 44 3 0.381 0.421 0.380 0.347 0.368 0.414 0.368 55 LR for common reduced form parameters num. of rejection: 1000 num. of rejection: 1000 LR for overidentifying restrictions num. of rejection: 1 num. of rejection: 5 Note: Results obtained through 1000 replications for each window width. true param. -1.162 -0.237 -0.087 0.634 1.402 0.127 0.063 -0.362 -0.196 0.359 0.519 -0.057 -0.039 -0.426 -1.816 1.190 -0.474 -1.150 0.351 0.140 0.061 0.849 -0.916 0.255 0.039 0.030 0.014 0.014 0.014 0.102 0.087 0.033 0.070 0.059 0.419 0.273 0.469 0.810 0.355 first decile -1.735 -0.285 -0.134 0.591 1.089 0.094 0.074 -0.709 -0.227 0.280 0.512 -0.103 -0.040 -0.511 -2.640 0.830 -0.511 -1.269 0.191 0.067 0.041 0.667 -0.987 0.237 0.032 0.026 0.013 0.013 0.013 0.079 0.066 0.028 0.055 0.064 0.336 0.240 0.443 0.730 0.348 26 Figure 1: Interest rates (left panel) and spreads (right panel), January 2005 - March 2014. 45 ESBRYLD PTBRYLD ITBRYLD 45 40 IRBRYLD GRBRYLD BDBRYLD 40 es_ge pt_ge it_ge ir_ge gr_ge 35 35 30 30 25 25 20 20 15 15 10 10 5 5 0 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 Figure 2: Actual and fitted spreads (left panel), residuals (middle panel) and residuals in absolute value (right panel), January 2005 - March 2014. Vertical bars: break dates. 5 es-ge es-ge fitted 2010 ir_ge ir-ge fitted 0 2010 pt-ge pt-ge hat 2005 2010 gr-ge gr-ge fitted 20 2010 it-ge it-ge fitted 2.5 2005 2010 2010 gr-ge residuals 2005 2005 4 2010 abs pt-ge residuals 2010 abs gr-ge residuals 2 2010 it_ge residuals 2005 1.0 0 2010 abs ir-ge residuals 0.5 2005 1 2005 1.5 pt-ge residuals 2005 5 2010 0.5 2005 1 2005 1.5 ir-ge residuals 0 2005 5.0 2010 -1 0 40 1 abs es-ge residuals 0.25 2005 -1 2005 10 0.75 es-ge residuals -0.5 0 2005 10 0.5 2010 abs it-ge residual 0.5 2010 27 2005 2010
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