This paper explores the effect of the return and volatility spillover between the Standard and Poor’s 500 index and FTSE All-Share index using the AG-DCC_ Dynamic Conditional Correlation model over the sample period from April 1995 to April 2019. It demonstrates that the Standard and Poor’s 500 return and volatility are crucial in forecasting the market’s future dynamics of the FTSE All Shares where it finds a significant spillover effect for both return and volatility from the Standard and Poor’s 500 to FTSE All Shares, while weak evidence has been found in the opposite direction, that is, an insignificant spillover effect for both return and volatility from FTSE All Shares to the Standard and Poor’s 500. In addition, the paper also finds high Dynamic Conditional Correlation (DCC) between both the Standard and Poor’s 500 and FTSE All Shares. Therefore, it finds asymmetric correlation and transmission mechanisms between the Standard and Poor’s 500 and FTSE All Shares, which means there is an asymmetric interconnectedness between two markets, so allocating assets between two markets will not benefit investor portfolios as investing in high-yielding shares do.