The article discusses how common investments like corporate bonds and CDS portfolios can have higher combined risks than just credit or spread risks alone. By separating migration risk from default risk, total risk can be more accurately estimated. The researchers found that under certain conditions, the total value-at-risk can be 50% larger than the sum of spread and credit risks, with an even stronger effect for expected shortfall. This study improves on previous research by defining conditions where risk separation is beneficial.