Modeling Issues to be addressed For Credit Risk in Sub-Prime Markets.
Key word: securitization, credit risk, transfer, modeling, sub-prime crisis.
The advantages and disadvantages of securitization for issuers and investors: Securitization is a structured finance process, which involves pooling and repackaging of cash-flow producing financial assets into securities that are then sold to investors. For issuers, the advantages of the securitization are obvious: First, securitization reduces funding cost: through securitization, a company ranked BB but with AAA cash flows could be able to borrow at possibly AAA rates. The difference between AAA and BB debt can be hundreds of basis points. Second, reduces asset-liability mismatch: depending on structures chosen, securitization can offer perfect matched funding by eliminating funding exposure in terms of both duration and pricing basis. Securitization allows banks whose liability book or funding is from borrowing to create a self-funded asset book. Third, lower capital requirements: Some firms, due to legal, regulatory or other reasons, have a limit or a range that their leverage is allowed to be. Securitization can allow companies to maintain the ‘earning power’ of asset while lessening their equity on their balance sheets. Fourth, transfer risks: securitization makes it possible to transfer risks from an entity that does not want to bear to one that does. These kinds of risks include credit, liquidity, prepayment, reinvestment and asset concentration.For the credit risk, the issuer transfers their credit risk to the investors who want to bear the credit risk, meanwhile, accepting the risks brought by securitization process itself: since securitization is a structured transaction which may include par structures as well as credit enhancements that are subject to risks of impairment, such as prepayment, as well as credit loss, especially for structures where there are some retained strips. For the investors, the benefits of holding the securitization asset are the opportunities to potentially earn a higher rate of return, to invest in a specific pool of high quality credit-enhanced assets, the diversification of portfolios and the isolation of risks from parent entity. Since the assets that are securitized are isolated from the assets of the originating entity, under securitization it may be possible for the securitization to receive a higher credit rating than the “parent,” because the underlying risks are different.Meanwhile, the risks exposed to investors are accompanied with the benefit from the securitization: First, liquidity risk, which arises from situations in which a party interested in trading an asset can not do it because no body in the market wants to trade that asset. Second, Credit Risk: default risk is generally accepted as a borrower’s inability to meet interest payment obligations on time. Third, event risk: some current events will cause the fluctuation of the security prices. Fourth, current interest rate fluctuations: the same risks faced by all other fixed-income products.
The new requirement of risk management
The securitization process transfers the credit risks from lender to common investors and making the risk management more complicate and high tech. As one of the tools of Credit Risk Transaction (CRT), securitization requires an in-depth understanding of credit risk not only for risk management companies but for the common market participants.
Market participants transacting in CRT instruments should have the capacity to understand and assess the credit-related risks inherent in these instruments. This should include the capacity to understand the major variables on which the valuation of the instrument depends and how the valuation of the instrument will be affected by changes in these variables. Market participants should seek to ensure that their measures of credit exposures to individual obligors are as comprehensive as possible, for example by including both direct exposures as well as indirect exposures from CRT transactions.
As the whole process of securitization above, the participants in the market face different risks, thus requiring diversified management requirements. Several credit risk models are created to different participants. And the process of securitization is classified into different markets. And specific market management tools are designed to address the market issues.
Modeling Issues need to address for the new requirements
Firms that rely on models to assess the valuation and risks of CRT instruments should have sufficient staff and expertise to properly understand the assumptions and the limitations of those models, and to manage their usage appropriately.
Firms should assess the extend to which trading/hedging approaches in CRT instruments may leave the firm exposed to risks that are not routinely captured in the firm’s risk management calculations (eg, jump to default/ or other issuer-specific risks and basis risks). Firms should regularly evaluate the need to incorporate such risks into their routine risk measurement calculation.
Different models are targeted at different risk holders and intermediate authority in the securitization process. For example, development of regulatory minimum capital standards for credit risk based on banks’ internal risk measurement models is the response to the new requirement of bank capitals according to Basel Code II. And Benchmarking Default Prediction Models to testify the normal used models and recalibrate these powerful models.
Sub-prime Mortgage Crisis and its effect to the modeling issues
The securitization of mortgage loans is a complicate process that involves a number of different players.
The frictions among these players can be concluded as:
1:Frictions between the mortgagor and originator: Predatory Lending
2:Frictions between the originator and arranger: Predatory Lending and Borrowing
3 Frictions between the arranger and third parties: Advance Selection
4: Frictions between the servicer and the mortgagor: Moral Hazard.
5:Frictions between the servicer and third-parties: Moral Hazard.
6:Frictions between the asset manager and investor: Principal Agent.
7:Frictions between the investor and credit rating agencies: Model Error.
Five frictions above are believed as the causes of the sub-prime crisis. The problems begin from the Friction1: many products offered to sub-prime borrowers are very complex and subject to misunderstanding and/or misrepresentations. This opened the possibility of both excessive borrowing ( predatory borrowing )and excessive lending(predatory lending).
Friction 6 brings a principal-agent problem. In particular, it seems that investor mandates do not adequately distinguish between structured and corporate credit ratings. Asset managers have an incentive to reach for yield by purchasing structured debt issues the same credit rating but higher coupons as corporate debt issues.
Friction 3 worsened the phenomenon, without due diligence by the asset manager, the arranger???s incentives to conduct its own due diligence are reduced. Moreover, as the market for credit derivatives developed, the arranger was able to limit its funded exposure to securitizations of risky loans. Together, these considerations worsened the friction between the originator and arranger, opening the door for predatory borrowing and provides incentive for predatory lending ( Friction 2).
The inability of the rating agencies to recognize the arbitrage by originators and respond appropriately meant that credit ratings were assigned to sub-prime mortgage-backed securities with significant error. The friction between investors and the rating agencies is the final nail in the coffin( Friction 7). Even though the rating agencies publicly disclosed their rating criteria for sub-prime, investors lacked the ability to evaluate the efficacy of these models.
All these issues need to address in the modeling in the credit risk management, especially the rating flaw in the securitization market will cause great damage to the sub-prime mortgage markets.
Reference:1 T Sabarwal “Common Structures of Asset-Backed Securities and Their Risks, (December 29, 2005) 2 Fixed Income Sectors: Asset-Backed Securities - A primer on asset-backed securities, Dwight Asset Management Company (2005).
3 Credit Risk Transfer, Basel Committee on Banking Supervisor. The Joint Forum, (October, 2004)
4 Credit Securitization and Credit Derivatives: Financial Instruments and the Credit Risk Management of Middle Market Financial Loan Portfolios. Sabine Henke /Hans-Peter Burghof /Bernd Rudolf (January,1998)
5 Understanding the Securitizations of Sub-prime Mortgage Credit.Federal Reserve Bank of New York Staff Reports (March 2008)