In July 2019, the Financial Stability Institute (FSI) of the Bank for International Settlements (BIS) published a study of the application of proportionality under Pillar 2 of the Basel framework. Sixteen jurisdictions were surveyed to examine their application of proportionality and how they implemented Pillar 2 principles. FSI stated that the key aim of the survey was, "to determine whether and, and if so, how supervisory authorities apply proportionality in tailoring risk management expectations and supervisory practices according to the size, complexity and risk profile of regulated entities."

The Basel Committee on Banking Supervision created a three pillar approach to the oversight of international banks, designating Pillar 1 to outline risk-based capital (RBC) rules, which are subject to supervisory review pursuant to Pillar 2 regulatory requirements and disclosure requirements set forth in Pillar 3. Pillar 2 requires an assessment of risk profile through a cumulative set of risk management requirements coupled with risk-based supervision (RBS). 

FSI's "Proportionality Under Pillar 2 of the Basel Framework", can be found here.