Systemic risk in banking systems is a crucial issue that remains to be completely addressed. In our toy model, banks are exposed to two sources of risks, namely, market risk from their investments in assets external to the system and credit risk from their lending in the interbank market.
The excessive increase of leverage, i.e. the abuse of debt financing, is considered one of the primary factors in the default of financial institutions since it amplifies potential investment losses. On the other side, portfolio diversification acts to mitigate these losses.
The Thesis investigates from a theoretical perspective the relationship between leverage, diversification and systemic risk. Moving from the folk wisdom that asset diversification enhances financial stability by dispersing credit risks, we contribute to the debate shedding light on a critical facet of this strategy.
Systemic risk, here meant as the risk of default of a large portion of the financial system, depends on the network of financial exposures among institutions. However, there is no widely accepted methodology to determine the systemically important nodes in a network.