Before revision:  In particular, we are combining this network-based analysis and a general dynamic factor decomposition in a study of the volatilities of the stocks of the Standard \&Poor's 100 index over the period 2000-2013. This approach allows us to decompose the panel into two components which represent the two main sources of variation of financial time series: common or market shocks, and the stock-specific or idiosyncratic ones. While the common components, driven by market shocks, are related to the non-diversifiable or {\it systematic } components of risk, the idiosyncratic components show important interdependencies which are nicely described through network structures.
After revision:  In particular, we focus on the so-called {\it systematic } components of risk, the idiosyncratic components show important interdependencies which are nicely described through network structures.