For the past few years, the literature on risk connectedness in international stock markets has explored the interdependence of risks across stock markets globally. Several studies have found that risk connectedness tends to escalate during periods of market stress, such as financial crises. Studies have also found that the degree of risk connectedness between stock markets can vary depending on the specific markets considered and the time period studied. Overall, the literature highlights the need to better understand the risk connectedness in international stock markets to inform investment strategies and public policy decisions. Let us examine previous studies on this subject more closely.
2.1. Financial risk network at the firm or sector level
The interconnectedness of financial risks within a firm or sector occurs when a firm’s financial risk has an indirect or direct influence on the financial risks of other firms within the same sector. For example, if a firm in a sector experiences financial difficulties, this can lead to a cascade of financial losses throughout the sector because of exposure to common risk factors such as supplier disruptions or declining market demand. At the firm level, financial risk networks can be used to analyze and manage the interdependence of various financial risks, such as credit, liquidity, and market risks. Firms can use this information to identify and address sources of systemic risk and make informed investment decisions. At the sector level, a financial risk network analysis can inform public policy decisions aimed at promoting stability and resilience in the financial system.
Many studies have analyzed the formation and structure of financial risk networks at the firm or sector level. Among others, in a study on the stock market in China, Wu [
32] identified the financial, industrial, and energy sectors as the most significant contributors to systemic risk, whereas Wu et al. [
33] determined that the industrial sector had the greatest systemic importance among the Chinese stock market sectors. Additionally, Zhang et al. [
34] examined the tail risk network of Chinese sectoral markets and analyzed systemic risk linkages using the conditional VaR (CoVaR) approach. Arreola Hernandez et al. [
35] explored the interdependence structure of the bank return network of emerging and developed Asia-Pacific countries. Ngene [
36] explored asymmetric and time-varying volatility spillovers among US sector equities. Wu et al. [
37] analyzed systemic risk connectedness in a network of global energy companies and revealed that US stock market volatility and financial market sentiment are the major drivers of time-varying risks. Shen et al. [
38] investigated risk spillovers within Chinese sectors using the generalized variance decomposition framework of the vector autoregression (VAR) model.
2.2. Financial risk network using a bivariate approach
To measure the network connectedness among financial markets, researchers have used various methods, such as correlation analysis, the Granger causality approach, the transfer entropy approach, and the variance decomposition of the VAR model. The most popular method in financial network analysis is calculating pairwise correlations. In a network, markets (sectors, institutions, or firms) are nodes, and correlations are links. For example, Chi et al. [
39] built a network of US-listed stocks using the calculated cross-correlations of price returns and trading volumes. Giroud and Mueller [
40] used correlations to construct internal networks of firms and examined the transmission of local shocks across regions in the US through these networks. Zhou et al. [
41] investigated special stock price behaviors in the Chinese A-share stock market using correlation-based stock networks.
The Granger causality network identifies causality by detecting the presence of information flow in a linear relationship, as proposed by Granger [
42]. As this approach has the advantage of being based on statistical tests, many studies have applied this model. For example, by applying the Granger causality network, Billio et al. [
43] analyzed the connectedness and system risk of four types of finance and insurance sectors, and Výrost et al. [
44] analyzed the network between 20 stock markets. Wang et al. [
45] employed VaR and Granger causality risk test to construct an extreme risk spillover network that measured the connectedness among financial institutions and quantified the extent of extreme risk spillovers.
The Granger causality approach only considers the direction of causality and not the degree of causality in terms of the magnitude of information flow. If the quantity of information flow between the two markets is of greater importance, the transfer entropy approach becomes more relevant. A transfer entropy approach is a useful tool for quantifying information transfer within a network numerically [
46]. Since Schreiber [
47] proposed the concept of transfer entropy, it has been applied in many fields. Sensoy et al. [
48] applied the transfer entropy method to investigate the intensity and direction of the information flow between stock prices and foreign exchange rates in emerging countries. Gong et al. [
49] analyzed stock market connectedness and found that the total connectedness of the market increased during periods of crisis. Nicola et al. [
50] used daily stock data from 74 listed US banks and investigated the US bank network. García-Medina and Luu Duc Huynh [
51] examined the predictive power of the determinants of Bitcoin prices by employing the transfer entropy approach. Tiwari et al. [
52] applied transfer entropy to investigate the information flow between government bonds and stock markets in the G7 countries.
If tail risks are crucial, then the copula approach is suitable for building a tail-dependence network. For example, Münnix and Schäfer [
53] investigated the statistical dependencies in the US stock market using a copula approach and revealed that many dependencies are from the tails of the marginal distributions. Changqing et al. [
54] explored risk contagion between international and Chinese stock markets using a dynamic copula model and revealed that risk contagion is identified by lower tail dependence. Xixi et al. [
55] utilized copula tail correlation to construct a complex network of the Chinese stock market and analyzed the network structure of the market. Wen et al. [
56] employed a copula model to investigate the edge information of a stock price network.
2.3. Financial market risk network using a multivariate system approach
The pairwise correlation and Granger causality approaches focus only on bivariate linkage and thus fail to measure overall systemic connectedness. The VAR approach can analyze the relationship in a multivariate system as a whole. Diebold and Yilmaz (hereafter, DY) [
15,
30,
31] suggest the most popular model of the VAR approach. Diebold and Yilmaz [
31] suggested a network topology employing the variance decomposition method. They constructed stock returns and volatility networks by measuring the time-varying connectedness of the stock return volatilities of major US financial institutions using variance decomposition.
The DY approach has been applied to spillover studies on several financial markets. For example, Mensi et al. [
57] examined the risk spillovers and hedging characteristics between precious metals and currency markets at three-time horizons using the DY index method. Using a DY spillover index approach, Arreola Hernandez et al. [
58] investigated the spillovers between a portfolio of precious metal commodities and equity markets. Kang et al. [
59] constructed a system of oil, gold, and US equity sector markets to explore the spillover effects in the system by employing the DY spillover index method.
Recently, several techniques have been developed to improve the DY method. Demirer et al. [
60] introduced the Least Absolute Shrinkage and Selection Operator (LASSO) method into high-dimensional networks to overcome the limitations of the VAR model in constructing low-dimensional networks. They construct a network of publicly traded subsets of the world’s top 150 banks. Du et al. [
27] also investigated multiscale tail risk spillovers across global stock markets at different frequencies by employing LASSO-based network connectedness. Baruník and Křehlík [
61] introduced the DY framework, which used the spectral representation of variance decompositions to measure the connectedness between financial variables resulting from heterogeneous frequency responses to shocks. Baruník and Kocenda [
62] applied an extended DY approach to high-frequency intraday data and examined the total, asymmetric, and frequency connectedness between oil and foreign exchange markets. Youssef et al. [
14] used the time-varying parameter VAR (TVP-VAR) of the DY method and investigated the dynamic connectedness between the eight stock indices affected by the COVID-19 pandemic. They also analyze how economic policy uncertainty affects this connectedness. Chatziantoniou et al. [
63] examined sectoral stock market connectedness in India by employing a TVP-VAR connectedness approach and revealed that connectedness was strongest during the GFC. Zhou et al. [
64] used a TVP-VAR DY model, constructed a network in Chinese sectoral stock markets, and analyzed sectoral risk spillovers based on high-frequency data. Alshater et al. [
65] explored the connectedness among several regional FinTech indices and analyzed how the Russia-Ukraine war affected the dynamic spillover using the TVP-VAR DY and time-frequency connectedness network approaches.
Some studies have focused on measuring the system risk in a financial network. Adrian and Brunnermeier [
66] introduced the CoVaR method to measure system risk according to the institutions’ leverage, size, and maturity mismatch. Al-Yahyaee et al. [
67] used a CoVaR and ΔCoVaR approach and studied the systemic risk among the Sharia, Sukuk, and Gulf Cooperation Council (GCC) stock markets. Wu et al. [
68] analyzed the tail risks of 28 stock markets using the conditional autoregressive value-at-risk model.
In addition, by applying the dynamic model averaging approach, Dong et al. [
7] explored how the interdependent structures between economic factors and stock markets changed during the COVID-19 outbreak. Their findings revealed that the dependence structures experienced significant changes during the COVID-19 outbreak and that economic factors had a stronger impact on developed stock markets than on emerging Asian markets. Hanif et al. [
69] analyzed connectedness spillover effects, and nonlinear dependence between European emission allowance prices and clean/renewable energy sector equity indices by employing the time-frequency DY model and TVP copula approaches.
Remarkably, previous studies have mainly concentrated on examining the connectedness of downside risks and have not considered upside risks and asymmetry in risk connectedness. In the stock market network, upside risk connectedness is another type of systemic risk, which can lead to future losses and high uncertainty [
28]. In this context, it is important to measure and analyze the upside and downside risk connectedness together and utilize the information in policy-making for stock market stabilization and international investors’ risk management. There have been several studies on this topic. Baruník et al. [
70] suggested a method to estimate asymmetries in volatility spillovers and revealed that asymmetries emerge because of bad and good volatility in the US stock market. BenSaïda [
71] investigated asymmetric volatility spillovers across the G7 stock markets and discovered that asymmetric connectedness is time-varying. Li [
72] dissected the influence of COVID-19 on global stock markets by employing the DY approach and discovered that volatility spillovers are time-varying, crisis-sensitive, and asymmetric. Mensi et al. [
73] investigated the asymmetric volatility connectedness among stock markets by analyzing high-frequency data from 16 stock markets and found that bad volatility dominates good volatility. Mensi et al. [
74], employing the DY spillover index, investigated the dynamic asymmetric volatility connectedness among US equity sector markets and revealed that the network of connectedness among sectors demonstrates asymmetric behaviors. Using high-frequency data from the COVID-19 period, Shahzad et al. [
75] analyzed asymmetric volatility spillovers among Chinese stock markets and discovered that bad volatility spillover shocks dominate good volatility spillover shocks.
As mentioned in previous studies, various models have been applied and analyzed between markets (or industries) to analyze the risk spillover effects in many studies. However, the model for calculating the extreme risks was not applied, and the analysis of the spillover effect was insufficient when applying the upper risk. Therefore, this study provides a new framework for computing networks and connectedness by applying the VaR model, which can estimate extreme risks (upside and downside risks).