Integration and volatility spillover amongst banks: a cross-correlation analysis
Authors: Rehman Mobeen Ur , Vo Xuan Vinh 
Published: February 2023

PurposeThe rising interconnectedness between international banks, at one end, allow participants to share risk and diversification which leads to stable local lending and increase in competitiveness, however, at the other end poses potential for volatility spillover and thereby contagion phenomena. Therefore, investigating the presence of co-integration amongst international banks can provide useful information about risk spillover in times of financial turbulenceDesign/methodology/approachThe authors employ wavelet correlation and wavelet multiple cross-correlation strategies, following an initial decomposition of returns series through maximal overlap discrete wavelet transformation (MODWT).FindingsThe results indicate high integration level between Citibank and Deutsche Bank whereas potential of diversification exists between pairs of Citibank–Hong Kong and Shanghai Banking Corporation and Bank of America–Deutsche Bank, with former more evident in short- and medium-term relationship and later in long-run investment horizon. This paper carries implications for investors, fund managers and policymakers in foreseeing the prospects of contagion attributable to high level integration levels.Practical implicationsImplications for cross-border banking integration includes the presence of common lender effect which appears as a dominant factor for cross-border contagion. Therefore, banks based in different countries should focus more on funds diversification rather than borrowing much from any single creditor. Furthermore, foreign operations based on subsidiaries instead of relying on direct cross-border lending can help in reducing volatility of the foreign financial resources. Nevertheless, based on the results and significant strand of existing literature, the presence of contagion is inevitable, and therefore, a careful consideration of cross-border banking supervision and co-operation by the financial authorities can help in mitigating the volatility of global capital flows.Originality/valueFirst, this study fills gap in the existing literature regarding the discussion on portfolio diversification opportunities in the banking sector. The banking sector is usually perceived as a main source of fixed income securities or financing; however, on the contrary, investors may also be interested for investments in publicly listed bank's stock. Most of the work regarding portfolio diversification revolves around capital market instruments; however, publicly listed shares of largest bank also present an avenue for diversification. Second, major fundamentals and the associated factor for banks performance are reflected in the its profits, either these profits result from large customer base or proper allocation of bank's assets, etc. Therefore, returns of these banks serve as a barometer for their performance and co-movement between any two banks can highlight the presence and extent of their underlying association. Third, the authors apply the latest extensions in wavelet techniques after decomposing returns series through the MODWT framework. This decomposition followed by wavelet estimations allow us to investigate banks integration level across different time and frequency space thereby carrying implications for both short- and long-run investors. Fourth, by analysing the presence of returns co-movements, the authors can predict the extent of plausible contagion since the recent global financial crisis of 2008–2009 used banks as the main medium of propagation of shocks. Fifth, the work presents many implications for the investment community, major trading partners associated with banks through different instruments and for policymakers so that the effect of contagion can be anticipated or at least mitigated in case of future financial turbulence.HighlightsWe investigate portfolio diversification opportunities in the banking sector.Time-frequency returns co-movements is measures by applying wavelet multiple correlation and cross-correlation techniques on decomposed return series.Deutsche Bank and Bank of America act as highest transmitter and recipient of volatility, respectively using the spillover approach of Diebold and Yilmaz (2012).Citibank and Deutsche Bank exhibit high pairwise correlation indicating no diversification benefits.Citibank exhibits high level of integration with other banks in the short- and medium-run whereas Deutsche Bank exercises high integration levels in the long-run investment period.