Recent turbulences in financial markets are not only a challenge for the actors in the front offices of the related institutions, but also represent a serious challenge for the IT departments in the back offices of banks etc. We present a simulation model that shows how Grid computing increases the resilience and quality-of-service of IT infrastructure in departmentalized enterprises in the presence of shocks. Grid computing also reduces the costs deriving from the cancellation of jobs in times with a high volatility of computational load. The model can be used to find the appropriate type of IT infrastructure for different financial service institutions. Our simulations' findings are also likely to encourage the introduction of Grid computing for related business branches and applications.