This paper provides a model of systemic panic among financial institutions with heterogeneous fragilities. Concerns about potential spillovers from each other generate strategic interaction among institutions, triggering a preemption game in which one tries to exit the market before the others to avoid spillovers. Although financial contagion originates in weaker institutions, systemic risk depends critically on the financial health of stronger institutions in the contagion chain. This analysis suggests that when concerns about spillovers prevail, then 1) increasing heterogeneity of institutions promotes systemic stability and 2) bolstering the strong institutions in the contagion chain, rather than the weak, more effectively enhances systemic stability.