Quantifying the contagion effect of the 2008 financial crisis between the G7 countries (by GDP nominal)

•We apply ρDCCAρDCCA to analyze the stock market of the G7 countries in GDP (nominal).•We analyzed the 2008 financial crisis in terms of ρDCCAρDCCA, in function of time.•ΔρDCCAΔρDCCA is defined in order to measure the contagion/interdependence effect.

In this paper we quantify the cross-correlation between the adjusted closing index of the G7 countries, by their Gross Domestic Product (nominal). For this purpose we consider the 2008 financial crisis. Thus, we intend to observe the impact of the 2008 crisis by applying the DCCA cross-correlation coefficient ρDCCAρDCCA between these countries. As an immediate result we observe that there is a positive cross-correlation between the index, and this coefficient changes with time between weak, medium, and strong values. If we compare the pre-crisis period (before 2008) with the post-crisis period (after 2008), it is noticed that ρDCCAρDCCA changes its value. From these facts, we propose to study the contagion (interdependence) effect from this change by a new variable, ΔρDCCAΔρDCCA. Thus, we present new findings for the 2008 crisis between the members of the G7.