Other elements would include how the bank's portfolio of business loans would be affected by the same event, including through the second-round effects of households' spending responding to the deterioration in their financial position. A shock large enough to cause the household sector significant problems in servicing mortgages would presumably be associated with some belt tightening for business borrowers too.
Hence there could be a correlation between the two portfolios, and not necessarily the same one as in the past. These interrelationships point to stress testing, for individual institutions and systems, as the way in which assessments of stability and resilience need to be conducted.