%0 Journal Article %T Dynamics of multivariate default system in random environment %A Nicole El Karoui %A Monique Jeanblanc %A Ying Jiao %J Quantitative Finance %D 2015 %I arXiv %X We consider a multivariate default system where random environmental information is available. We study the dynamics of the system in a general setting and adopt the point of view of change of probability measures. We also make a link with the density approach in the credit risk modelling. In the particular case where no environmental information is concerned, we pay a special attention to the phenomenon of system weakened by failures as in the classical reliability system. %U http://arxiv.org/abs/1509.09133v1