The study looked at how U.S. and Canadian corporate bond markets are connected. They found that in normal times, the two markets don't affect each other much. But during crises, the bond markets become more closely linked. In the U.S., different types of bonds became more connected during the 2007-2009 financial crisis and this connection continued after the crisis. In Canada, bonds from different sectors stayed connected over time, showing how bonds in the Canadian market depend on each other.