(9)Given the wide geographical and sectoral diversity of portfolios, it is not practicable to prescribe the precise data sources that must be used for each listed indicator in every jurisdiction of the world and every sector. Moreover, institutions are already required under Regulation (EU) No 575/2013 to use reliable data and to have robust systems in place for validating the estimation of all risk parameters. As a result, institutions will in any event be required to demonstrate the accuracy and reliability of the data sources used by them for obtaining indicator values. It is therefore not necessary to lay down specific rules in this Regulation about the precise data sources to be used.