(15)For non-retail qualifying securitised exposures that are eligible for the retail treatment, institutions calculating K IRB should be required to verify and calculate the outstanding exposure values to a group of connected clients to comply with the requirement on pool diversification. Such a verification and calculation may, however, be difficult due to the lack of relevant data. The institution calculating K IRB should, therefore, only be required to undertake such verification and calculation to the best of its knowledge, such as on the basis of information about the debtors that was obtained from the originator, the seller, or the original lender, at the time of the origination of the exposures, or information obtained from the servicer either when servicing the exposures or in the course of its risk-management procedure.