The study looked at how banking crises spread internationally during the 2007-2009 financial crisis. They found that crises can be transmitted through three different ways - systematic, idiosyncratic, and volatility. These types of contagion were seen in 41 out of 50 countries studied. The research showed that when crisis shocks from another country spread through idiosyncratic contagion, it increased the chances of a banking crisis in the domestic system by almost 27%. However, exposure through systematic contagion did not always lead to instability in the domestic banking system. This suggests that reducing the potential for idiosyncratic contagion can help lessen the impact of banking crises on the economy.