We develop a stress-testing network model calibrated to the largest banks and investment funds in over-the-counter (OTC) derivatives markets. We examine the impact of the mandatory collateralisation of bilateral OTC derivatives on liquidity, counterparty, and systemic risks, as well as the impact of market frictions on participants’ ability to withstand liquidity shocks. The collateralisation of bilateral trades reduces counterparty and systemic risks but increases the prominence of liquidity-driven defaults and the potential for the central counterparty to transmit losses. Frictions such as fire sales, delayed payments, and no partial payments by defaulted counterparties greatly increase liquidity risk and systemic losses.

Using a large sample of European listed banks, we investigate the relationship between a bank’s business model and systemic risk between 2005 and 2020, a period which includes various episodes of instability. Our findings indicate that, during tranquil periods, banks with different business models exhibit similar sensitivity to systemic risk. However, during periods of instability, the type of business model becomes critical: investment banks contribute more to and are more exposed to systemic risk. Distinguishing between endogenous and exogenous crises, our results reveal that market-oriented banks contribute more to systemic risk when instability is endogenous to the financial sector. Conversely, focused retail banks consistently show lower contributions and exposures to systemic risk. Additionally, our findings highlight the importance of business model migrations in reducing systemic risk. Banks transitioning from diversified to more retail-oriented models reduce their systemic risk, whereas migrations in the opposite direction do not exhibit the same benefit. These findings underscore the importance of maintaining diverse business models in the banking sector to enhance financial stability. • The study investigates the relationship between a bank’s business model and systemic risk. • During tranquil periods, banks with different business models exhibit similar sensitivity to systemic risk. • During periods of instability, investment banks contribute more to and are more exposed to systemic risk. • Market-oriented banks contribute more to systemic risk when instability is endogenous to the financial sector. • Focused retail banks show lower contributions to and exposures to systemic risk across different crisis periods.