Ratings Based Capital Adequacy for Securitizations
39 Pages Posted: 10 Nov 2013 Last revised: 15 Nov 2015
Date Written: April 24, 2013
This paper develops a framework to measure the exposure to systematic risk for pools of asset securitizations and measures empirically whether current ratings-based rules for regulatory capital of securitizations under Basel II and Basel III reflect this exposure. The analysis is based on a comprehensive US dataset on asset securitizations for the time period between 2000 and 2008. We find that the short-fall of regulatory capital during the Global Financial Crisis is strongly related to ratings. In particular, we empirically show that insufficient capital is allocated to tranches with the highest rating. These tranches account for the greatest part of the total issuance volumes. Furthermore, this paper is the first to calibrate risk weights which account for systematic risk and provide sufficient capital buffers to cover the exposure during similar economic downturns. These policy-relevant findings suggest a re-calibration of RBA risk weights and may contribute to the current efforts by the Basel Committee on Banking Supervision and others to re-establish sustainable securitization markets and to improve the stability of the financial system.
Keywords: Asset-Backed Security, Basel II and III, Collateralized Debt Obligation, Economic Downturn, Mortgage-Backed Securities, Home Equity Loan Securities, Ratings-Based Approach, Regulation, Regulatory Capital, Risk Weights, Securitization
JEL Classification: G20, G28, C51
Suggested Citation: Suggested Citation