Unmasking return and volatility connectedness between the oil market and stock markets of the G20 countries

Our research addresses the increasing concern of interdependency in the global financial markets, especially the stock market of G20 nations (Australia, Argentina, China, France, Japan, and the USA) and the WTI (West Texas Intermediate) oil market between January 2017 and September 2025. The dynamic connectedness approach and quantile VAR are a strong check as we use them to determine the spillover effect in various market conditions. We find that the spillover effect in bullish and bearish market conditions is strong with the Total Connectedness Index (TCI) of 71.98% and 70.25%, respectively. In the normal case, the highest connectedness effect is achieved at tau=0.5, and this result is consistent with the dynamic TCI of 39.12%. Based on the varying market conditions, USA, Australia, and France are strong net transmitters, but WTI is a net receiver in a bullish and bearish market situation, then Argentina, China and Japan, respectively depending on the return spillover effects. The USA, France, and Australia can strengthen their leading position as a net transmitter in the volatility spillover. Japan is a net transmitter in bearish market conditions only in the volatility series, and it is a net transmitter in bullish market conditions only in the return series. This became particularly clear during the global epidemic, the war between Russia and Ukraine, and the ongoing tariff war. In general, our study points to the increased role of the USA stock market in world markets concerning WTI. These findings can be used by investors and policymakers to maximize returns and ensure market stability.