Recent financial disasters have emphasized the need to accurately predict extreme financial losses and their consequences for the institutions belonging to a given financial market. The ability of econometric models to predict extreme events strongly relies on their flexibility to account for the highly nonlinear and asymmetric dependence patterns observed in financial time series. In this paper, we develop a new class of flexible copula models where the dependence parameters evolve according to a Markov switching generalized autoregressive score (GAS) dynamics. Maximum likelihood estimation is performed using a two-step procedure where the second step relies on the expectation-maximization algorithm. The proposed switching GAS copula models are then used to estimate the conditional value at risk and the conditional expected shortfall, measuring the impact on an institution of extreme events affecting another institution or the market. The empirical investigation, conducted on a panel of European regional portfolios, reveals that the proposed model is able to explain and predict the evolution of the systemic risk contributions over the period 1999-2015.Recent financial disasters have emphasized the need to accurately predict extreme financial losses and their consequences for institutions' financial health and, more generally, for the safety of the broader economy. As a consequence of the ever increasing level of interconnection between economies, markets, and institutions, recent financial crises feature similar ingredients. Indeed, the recent global financial crisis of 2007-2008 and the European sovereign debt crisis of 2010-2011 have been characterized by the spread of the financial turmoil from the banking sector to the whole economy, leading to sharp economic downturns and recessions. A large empirical literature focusing on the propagation mechanisms provides evidence that, during huge crisis episodes, the failure of banks and financial institutions triggers other nonfinancial institutions through the balance sheet and liquidity channels, threatening the stability of real economy (see, e.g., (Adrian & Shin, 2010;Brunnermeier, 2009;Brunnermeier & Pedersen, 2009).The ability of econometric models to account for the negative consequences for the overall financial system of such extreme events strongly relies on their flexibility to feature the highly nonlinear and asymmetric dependence structures of financial returns. Over the years, the correlation coefficient has emerged as the most natural measure of dependence. However, despite its widespread use, the correlation fails to capture the important tails behavior of the joint probability distribution (see, e.g., Embrechts, McNeil, & Straumann, 1999, 2002. Hence modeling the tail dependence and the asymmetric dependence between pairs of assets has been becoming increasingly more important in today's financial markets. Furthermore, the linear correlation coefficient as a measure of dependence is usually associated with the assumption of J Appl Econ. 2019;34:43-65...