9. Monitoring the stressed period

In addition to the above-mentioned regular review, an institution should have in place procedures which ensure, on an on-going basis, that the specified stressed period remains representative, including when ,market conditions or portfolio compositions have been subject to significant change.

In order to put in place sound procedures for the ongoing monitoring of the relevance of a stressed period, an institution should document the soundness of the implemented approach. Monitoring may be based on a variety of factors which may differ among institutions. Factors to be considered include changes in market conditions, in trading strategies or also in portfolio composition. These factors may be analysed by comparing them to changes in the allocation of market values or notionals, in risk factor loadings, in the level of VaR or sensitivities, in the repartition of VaR or sensitivities over portfolios and risk categories, in the P&L and back-testing results or also by the impact of newly approved products on the risk profile.

In addition to the above-mentioned procedures, monitoring of Stressed VaR relative to VaR should be performed on an on-going basis, because, while in theory, due to differences in parameterisation, Stressed VaR can exceptionally be smaller than VaR, also at inception, this should not structurally be the case. The ratio between Stressed VaR and VaR at the moment of identification of the relevant stressed period should be used as a reference value for ongoing monitoring. Significant decreases in the ratio should be considered as indications for a potential need for review of a stressed period. A ratio between Stressed VaR and VaR below one should be considered as a warning signal triggering a review of the stressed period.

12 C. Stressed VaR methodology