“…However, being parametric, those models all suffer of the "curse of dimensionality": estimation, even panels of moderate size, rapidly becomes unfeasible. In order to overcome this problem, and in agreement with the Capital Asset Pricing Model (CAPM) idea of a market shock affecting all components of a financial index, factor structures on the returns have been developed jointly with GARCH modelling for the latent factors: see, for instance, Ng et al (1992), Harvey et al (1992), Diebold and Nerlove (1989), Van der Weide (2002), Connor et al (2006), Sentana et al (2008), or Rangel and Engle (2012). All those factor models, however, are static, and mainly of the exact type (strictly no idiosyncratic cross-correlations); thus, they do not fully exploit the time series nature of the data.…”