Do information contagion and business model similarities explain bank credit risk commonalities?

This paper revisits the credit spread puzzle for banks from the perspective of information contagion. The puzzle consists of two stylized facts: Structural determinants of credit risk not only have low explanatory power but also fail to capture common factors in the residuals. We reproduce the puzzle for European bank credit spreads and hypothesize that the puzzle exists because structural models ignore contagion effects. We therefore extend the structural approach to include information contagion through bank business model similarities. To capture this channel, we propose an intuitive measure for portfolio overlap and apply it to the complete asset holdings of the largest banks in the Eurozone. Incorporating this unique network information into the structural model increases explanatory power and removes a systemic common factor from the residuals. Furthermore, neglecting the network likely overstates the importance of structural determinants. JEL Classification: G01, G21, C32, C33, C38