The intent in producing this Handbook is to familiarize researchers and policy makers with the many aspects of systemic risk. The Handbook contains some 32 chapters prepared by experts from a multitude of academic and professional backgrounds. What will become clear to the reader are both the complexity of systemic risk and the necessity for bringing together multiple academic disciplines to better understand systemic risk and for designing policies to mitigate the impact of a systemic crisis upon the global economy. Recent history has shown us not only the enormous cost of a systemic crisis but also how woefully unprepared and illequipped governments and private markets have been to prevent a systemic crisis or minimize its impact.

The first issue in addressing systemic risk is to define the system. Despite the large volume of recent articles on the topic of systemic risk, there has been little attention paid to what is endogenous to the system and events that are external. The financial system is a system in which humans, their emotions, politics and responses to incentives play a critical role. The topology of the system is extremely complex, dynamic, and not well studied. The system does not recognize national boundaries. Events in the US have impacted the markets across the globe. European debt crisis is impacting the Americas, Africa, and Asia. The common use of the terms “Wall Street” and “Main Street” seems to suggest that the two are separable.