Definitions and General Terminology

For risk-based capital purposes, an internal ratings-based (IRB) pool means a securitization pool for which a bank is able to use an IRB approach to calculate capital requirements for all underlying exposures given that it has approval to apply IRB for the type of underlying exposures and it has sufficient information to calculate IRB capital requirements for these exposures. A bank which has a SAMA-approved IRB approach for the entire pool of exposures underlying a given securitization exposure that cannot estimate capital requirements for all underlying exposures using an IRB approach would be expected to demonstrate to SAMA why it is unable to do so. However, SAMA may prohibit a bank from treating an IRB pool as such in the case of particular structures or transactions, including transactions with highly complex loss allocations, tranches whose credit enhancement could be eroded for reasons other than portfolio losses, and tranches of portfolios with high internal correlations (such as portfolios with high exposure to single sectors or with high geographical concentration). 18.16 For risk-based capital purposes, a mixed pool means a securitization pool for which a bank is able to calculate IRB parameters for some, but not all, underlying exposures in a securitization. 18.17 For risk-based capital purposes, a standardized approach (SA) pool means a securitization pool for which a bank does not have approval to calculate IRB parameters for any underlying exposures; or for which, while the bank has approval to calculate IRB parameters for some or all of the types of underlying exposures, it is unable to calculate IRB parameters for any underlying exposures because of lack of relevant data, or is prohibited by SAMA from treating the pool as an IRB pool pursuant to 18.15.