In this study, we propose a wavelet-copula-GARCH procedure to investigate the occurrence of cross-market linkages during the COVID-19 pandemic. To explore cross-market linkages, we distinguish between regular interdependence and pure contagion, and associate changes in the correlation between stock market returns at higher frequencies with contagion, whereas changes at lower frequencies are associated with interdependence that relates to spillovers of shocks resulting from the normal interdependence between markets. An empirical analysis undertaken on six major stock markets reveals evidence of long-run interdependence between the markets under consideration before the start of the COVID-19 pandemic in December 2019. However, after the health crisis began, strong evidence of pure contagion among stock markets was detected.

Understanding the Stock Return-Inflation Nexus is a continuing concern among scholars. The main goal of the current study was to critically examine the view that the relation between stock return and inflation is potentially asymmetric. To capture the possibility of dynamic nonlinearity and, in turn, asymmetry, the nonlinear Autoregressive Distributed lag model (NARDL) was deployed. This study has identified that the responses of stock return are generally asymmetric. In other words, the results suggest that contractionary time appears to reduce the stock returns more than expansionary time does.

This study seeks, within the extended framework of the so-called environmental Kuznets curve (EKC), to analyse the nonlinear effect of economic growth and energy consumption on environmental pollution (measured by CO2 emissions) in 30 countries, over the period 2000 – 2018. The panel smooth transition regression (PSTR) model is used to allow such a relationship between variables in different economic regimes to be determined. According to the analysis results, this study strengthens the idea that the relationship can be described as a shaped business cycle, in which economic growth first increases environmental degradation, and then, after a certain growth (income) level has been reached, reduces it. This business cycle relationship suggests that environmental improvements will eventually occur as economies grow. Another implication of these results is the importance of using energy in a greener way to combat climate change and to sustain economic development.