(3)A highly concentrated pool of underlying exposures increases the risk of major losses in the securitisation. Since concentration risk is more prevalent in pools of underlying exposures which have a low granularity, it is necessary to lay down a threshold for the minimum granularity of the pool of underlying exposures measured by the effective number of exposures in the pool. Where the concentration risk is less prevalent, the forward-looking trigger should be subject to the average credit quality of the underlying portfolio. To set that trigger, the credit quality of the underlying portfolio should be measured since origination of the securitisation.