We propose an identified structural GARCH model to disentangle the dynamics of financial market crises. We distinguish between the hypersensitivity of a domestic market in crisis to news from foreign non-crisis markets, and the contagion imported to a tranquil domestic market from foreign crises. The model also enables us to connect unobserved structural shocks with their source markets using variance decompositions and to compare the size and dynamics of impulses during crises periods with tranquil period impulses. To illustrate, we apply the method to data from the 1997–1998 Asian financial crisis which consists of a complicated set of interacting crises. We find significant hypersensitivity and contagion between these markets but also show that links may strengthen or weaken. Impulse response functions for an equally-weighted equity portfolio show the increasing dominance of Korean and Hong Kong shocks during the crises and covariance responses demonstrate multiple layers of contagion effects.

Detecting contagion during financial crises requires the demarcation of crisis periods. We develop a method for endogenously dating both the start and finish of crises, along with measuring contagion effects. Identification is achieved by coupling smooth transition functions with structural GARCH. In an application to US equity, bond and REIT returns for 2001–2010, we identify four phases; a pre-crisis period to July 2007, two phases of crisis up to and following October 2008, and a post-crisis phase from mid-May 2009. We detect significant contagion during the crisis and find evidence that the post-crisis period has not returned to pre-crisis relations.