Credit Risk Measurement: Understanding Credit Risk
Existing credit risk measurement techniques measure credit risks on a relative scale. The Basel II Accord attempts to transform relative risk measures into absolute risk measures. To support the transformation process, the Accord has identified four drivers of credit risk: exposure, probability of default, loss given default, and maturity. The Accord has not yet fully recognized correlations among these four drivers. This series of articles from i-flex Consulting provides a measurement framework for these drivers for different products, counterparties, portfolio, industries, instruments, etc. Most banks presently recognize only probability of default at various levels of sophistication as the risk driver. In order to measure absolute credit risks, the measurement process requires transformation at three levels. It:
The eight articles in this series together describe the transformation of credit risk measurement at these three levels. The series aims to provide a framework to support transformation process by extracting methodologies, best practices, architecture and bench mark risk measures from the Accord, papers, studies, surveys published by BIS, and literature published by academics and banks to support or criticize the Accord.
Articles in this series
Credit mitigation techniques are used to reduce credit loss. Credit risk mitigations are of two types:
There are various ways to consider risk mitigation within credit risk measurement. Since credit loss is measured through credit drivers, risk mitigation techniques can be reflected in reduction of credit drivers.
|Exposure||Reduce the exposure||Basel has prescribed conditions for recognition of risk mitigation techniques to reduce LGD. However, instead of LGD it allows reduction in Exposure.|
|PD||Assign the risk weight applicable to the collateral or guarantor for the exposure or portion of the exposure.
Credit derivative can be used to reduce PD.
|PD cannot be lesser than PD of guarantor or credit derivatives.|
|LGD||Insurance amount received can be used to reduce the LGD.
Guarantees can be used to reduce LGD.
|This technique is recommended for retail mortgages. LGD is still not a developed technique for risk measurement.
LGD cannot be less than the LGD of guarantor.
|Maturity||In order to recognize a risk mitigant, there should not be maturity mismatch. Maturity of risk mitigants should be higher than the maturity of exposure.|
Collateral should be realizable to be effective. Factors affecting realization are:
To simplify the liquidity impact, the Accord has recognized liquid financial assets as eligible collaterals for the time being. Going forward, as the markets for other collaterals develop (for example, market for second-hand vehicles is quite liquid, markets in many of the countries have their own indices to measure the price trends), supervisors are likely to accept other liquid collaterals (and those collaterals are not necessarily going to be financial collateral) – the most likely candidates are vehicles, real estate and tradable physical assets titles. After liquidity, the most important thing to consider is the price the collateral is likely to realize. The volatility in the price needs to be considered. Since the Basel Accord recognizes financial assets, only the volatility of the financial assets is considered by the Accord and Basel Bench mark
|Liquidity||The Accord recognizes liquid assets as eligible collateral Assets.|
|Hair cuts||Use conservative methods and apply haircuts to the value of collaterals.
Relevant haircuts for the collaterals
|Relevant hair cuts for financial assets as collaterals||Currency mismatches
|Currency mismatches model||Currency volatility for 10 business days holding|
|Maturity mismatches between exposure and collateral||Both exposure and collateral be measured conservatively
Exposure should be gauged as the longest possible remaining time before the counterparty is scheduled to fulfil its obligation
Multiplier = residual maturity of collateral/residual maturity of exposure
Multiplier cannot exceed one
Maturity of exposure is taken as five years. Maturity of collateral should not be less than one year.
|Maturity Mismatch Model||(t-0.25)/(T-0.25)
t = min (T, residual maturity of the credit protection arrangement) expressed in years
T = min (5, residual maturity of the exposure) expressed in years
|Correlation||The credit quality of the counterparty and value of the collateral should not have positive correlation. Collateral with positive correlation will not provide any protection.|
These benchmarks (practices and models), also called comprehensive approach by the Accord, though prescribed for standard approach, can continue to be utilized for other approaches. This helps in smooth transformation. To further ease the transformation, risk weights of the exposure can be substituted with that of collateral to the extent of collateralization for banking books, provided there are no maturity mismatches.
Properties for eligible collateral – over the period of development of the Basel Accord, many additional types of collateral were recognized as eligible. This trend is likely to continue by the supervisors of various countries if it can be shown that the collateral has the following attributes:
Steps in valuation of assets, which lose value with usage and time (like vehicles, machinery, etc)
It is debatable whether guarantees and insurance are a form of risk protection or risk transfer. There are seven types of instruments used for credit risk transfer categorised as funded or non-funded.
Funded vs. Non-funded
Funding implies upfront funding where funds change hands at the beginning of the transaction. Funding is from the perspective of a risk shedder. Techniques for transferring credit risk, such as financial guarantees and credit insurance, have been a long-standing feature of financial markets. In the past few years, however, the range of credit risk transfer (CRT) instruments and the circumstances in which they are used have widened considerably. This is changing the role of banks as a Lender to Loan Originator to loan servicing.
Changing Role of Banks
|Loan Originator||As a loan originator, banks assess the credit risk. Rating Agencies continue to play a major role in risk assessment.|
|Loan funding||Banks are shifting loans off their balance sheet either individually or as part of a package through loan transfers and securitization. SPVs, Asset management companies, funds, hedge funds and insurance companies are emerging as the major providers of funds. The risk assessment role is still solely with Rating Agencies|
|Agency (loan servicing)||After transferring credit risk, banks continue to provide monitoring and servicing.|
CRT instruments typically change the relationship between borrowers and lenders and establish new relationships between lenders and those to whom they may pass on credit risk. Further, due to asymmetric information, principal/agent problems and incomplete contracts create problems of moral hazard and adverse selection.
Single Name Instrument
The following components are modelled:
Correlation: The industry presently uses crude methods for incorporating correlation. Modelling techniques used by various Agencies (in addition to the judgmental factors and credit conditions) are:
|Moody’s||Diversity Scores: it considers two factors – industry subcategory and Regions. Based on diversity scores, a virtual portfolio is built with the same mean and variance as the actual portfolio.|
|S&P||Monte Carlo method is used to model the asset value correlation. Two types of correlation are modelled – industry and general state of the economy. Asset values of the firms within the same industry are assumed to have 0.3 correlation and asset-backed securities are assumed to have a correlation of 0.1.|
|Fitch||Does not model correlation. Various types of limits are used.
Minimum size of junior tranche (based on weighted average rating of underlying assets), say 14 per cent.
Minimum number of industries in the portfolio (10).
Limit on the single industry not to exceed 20 per cent.
Limits on the top-three industry exposures (not to exceed 45 per cent). And each industry exposure cannot exceed 15 per cent.
Single obligor limit (1-2.5 per cent).
Actors in Credit Risk Transfer
Actors include: borrower; lender/risk shedder; lender’s creditor, shareholders and regulator; risk taker; and risk taker’s creditors, shareholders and regulator. It is a well-known fact that incentives for various actors in the transaction are different. CRT alters the existing incentives in their relationships and, by creating a new set of relationships amongst borrowers, lenders/risk shedders and risk takers, it potentially gives rise to moral hazard and/or conflicts of interest.
For a credit risk transfer, the following should be considered:
Following are the best practices to manage/minimize moral hazards or conflict of interest:
(i) Borrower and risk shedder
(ii) Borrower and risk taker
(iii) Risk shedder and risk taker
(iv) Risk shedder and its creditors, owners and regulators
The same is applicable for a risk taker or its creditors, owners and regulators.
The instrument used to transfer credit risk may not contain terms or conditions that limit the amount of credit risk transferred, such as those provided below:
The extent to which credit risk mitigation techniques are used vary with the size, business strategy and level of sophistication of the banking institution. Factors which determines the type of techniques used are
Managing residual risk arising from imperfect credit mitigation technique:
Take Note: Transformation Process – Timing is the most important element determining the choice of risk mitigation techniques. Collateral or guarantee is often taken ex-ante, as a part of the overall credit process. Credit derivatives are purchased ex-post, at a somewhat later stage in the life cycle of credit exposure. Risk mitigation instruments are also used for managing portfolio concentration.
Credit Risk Transfer evolved due to the arbitrage opportunities created by different regulatory treatments for credit risk for insurance companies. The difference has caught the eyes of regulators and regulation is likely to converge to Basel treatment. This aspect should be taken into account while entering into new contracts. This has a major impact on pricing and therefore on potential exposure.
Securitization is one of the ways to transfer the risk. However, many times, for various reasons, there is no clear break from the exposure or risk. The retained risk from securitization is reflected by investment in the BB or lower tranche. This is investment in the below investment grade bonds or in pure junk and represents a very high quantity of risk. In order to discourage banks from using a securitization mechanism as a means to arbitrage regulatory capital requirements, the amount invested is reduced from the capital (or needs 100 per cent capital). This is not because of the grade of the exposure, but because of the securitization. The following table shows the difference in risks by presenting the capital treatment.
The instruments used to transfer credit risk may not contain terms or conditions that limit the amount of credit risks transferred, such as those provided below: