Downturn model risk: Another view of the global financial crisis

Researchers and practitioners have spent ample resources modelling credit, explaining correlations between risk models as well as inputs and outputs. One popular example is asset correlation, which describes the co-movement between the asset value returns of corporate borrowers or issuers. Other examples are default correlations, correlations between default and recovery processes and correlations between risk categories such as credit, interest, liquidity or market risk. In statistical terms, correlations are often placeholders for relationships which cannot be explained and are also known as "seeming correlations". The 2008-9 global financial crisis caught us by surprise and showed that, starting with US subprime mortgage markets, other markets such as equity, credit and commodity markets have declined globally. These links have not been included into existing risk models, and this chapter identifies these links and shows . how to address these relationships in risk models