Journal of Risk Model Validation

Risk.net

Validation nightmare: the slotting approach under International Financial Reporting Standard 9

Lukasz Prorokowski, Oleg Deev and Jena-Daniel Guigou

  • Correspondence between the slotting scores and PDs is possible to satisfy the IFRS 9 rules on denotching and staging.
  • For the PD mapping methodology, both the target RWA and Expected Loss should be considered.
  • Since there are distinct slotting categories, the sequential process should be solved for each slotting category.
  • For the PD mapping methodology, the exposures should be differentiated by the maturity regulatory-prescribed thresholds.

This paper makes an important contribution to the practice of validation by focusing on an under-researched area of the slotting approach to real estate specialized lending under the International Financial Reporting Standard 9 (IFRS 9) framework. The paper introduces the concept of mapping the probability of default estimates to the slotting scores. A sequential process for deriving the correspondence between the slotting scores and probabilities of default of a particular obligor is proposed as a solution to adapting the slotting approach to the IFRS 9 rules. This solution is especially useful for capturing the increase in credit risk under the IFRS 9 rules using denotching and staging processes. All in all, this paper addresses the research questions of whether and how a slotting model can be used for IFRS 9 compliance purposes. In addition to the core aim of the paper, which is the provision of a probability of default mapping solution under the IFRS 9 framework, we also explain the methodology of a slotting model, discussing specific modeling choices for the real estate slotting approach aligned to the relevant regulatory framework. In doing so, we provide an example of a slotting model that can be used by practitioners as a challenger model during the validation exercise.

1 Introduction

The aim of this paper is to show the process of assigning probabilities of default (PDs) to the output of the slotting model used for specialized lending exposures in real estate. The need to map the final scores of the slotting model to the corresponding PDs is motivated by the International Financial Reporting Standard 9 (IFRS 9) requirements (International Accounting Standards Board 2009) and the fact that a slotting model does not produce PD estimates, but instead produces scores that assign a specialized exposure to one of the five slotting categories.

Under IFRS 9, the calculation of the expected credit loss (ECL) should consider the probability weighted amount of a loss (Gehrer et al 2014). This implies that the ECL calculation cannot be based on the simple slotting categories grouping strong or weak specialized lending projects. Further, the ECL is a function of a default probability and a loss given default (LGD) (Jacobs 2015). Therefore, as noted by Reitgruber (2013), it cannot be based on a model output that is not converted into PDs. Given the above constraints, the use of a slotting model becomes problematic in light of the IFRS 9 requirements. Recognizing the aforementioned problems, we propose a methodology for deriving the correspondence between the slotting scores and PDs of a particular obligor. We also advise on the potential IFRS 9 compliance gaps arising from the use of a slotting model.

Modeling credit risk of specialized lending exposures is regulated by the EBA’s “final draft regulatory technical standards on assigning risk weights to specialized lending exposures” (European Banking Authority 2016b). Using an example of a slotting model for the real estate projects, we explain the methodology of a slotting model for specialized lending exposures. In doing so, we advise on the modeling steps and the choice of risk factors that ensure compliance with the EBA’s standards.

We discuss two important themes: the modeling of credit risk for specialized lending exposures and the IFRS 9 regulatory framework. Both areas are relatively new to the banking sector and remain under-researched. The value of this paper comes from bridging theory and practice by providing practical insights into credit risk modeling for nonstandard exposures and advising on ensuring compliance with relevant credit risk regulations that currently shape the banking industry. Further, we propose an innovative methodology for mapping slotting scores to PDs as well as solutions for satisfying IFRS 9 requirements in this space.

The paper is organized as follows. Section 2 discusses the regulatory definition of the specialized lending exposures and provides practical insights into determining which real estate projects should be treated as specialized lending exposures. Currently, to the best of our knowledge, there are no academic studies discussing issues around the classification of the projects under the slotting approach for the specialized lending exposures, and the existing regulatory guidance is not sufficient. This section also presents a regulatory-compliant slotting model for real estate specialized lending exposures.

Section 3 introduces the model used for the slotting approach to the real estate specialized lending exposures. The output of this model is used as the basis of the PD mapping exercise. Section 3 also describes the data used for the analysis, which consists of the materiality figures for the introduced model. Finally, Section 3 discusses the proposed methodology of mapping the slotting scores to PDs. This section is central to the core aim of the paper to show how PDs can be assigned to limited slotting categories. In order to maximize the practical implications of this paper, the methodology is rooted in the Capital Requirements Regulation (CRR (see European Banking Authority 2016b)).

The analysis and results of applying the proposed methodology are presented in Section 4, which also advises on the IFRS 9 compliance gaps stemming from the mapping exercise. Section 5 provides future refinements to the process of deriving the correspondence between the slotting categories and risk estimates. The findings are summarized with our principal conclusions in Section 6.

2 Study background

2.1 Specialized lending

This section discusses the regulatory and business background for the treatment of specialized lending exposures. Pursuant to Article 147(8) of the CRR, specialized lending exposures constitute a unique subclass of corporate exposures under the internal ratings-based (IRB) approach. The regulation defines specialized lending exposures as

  • the exposure to a special purpose entity (SPE) created for the sole purpose of financing and operating physical assets,

  • the exposure that gives the credit institution a substantial degree of control over the assets and the income generated by these assets, and

  • the exposure with the primary source of repayment being generated by the financed assets and not the independent capacity of the obligor.

The above definition is in line with the Basel III view on specialized lending outlined in the BCBS’s publication on finalizing post-crisis reforms (Basel Committee on Banking Supervision 2017). The Basel III mechanics of the IRB approach categorize the specialized lending exposures into five subclasses of the corporate class: project finance, object finance, commodities finance, income-producing real estate (IPRE) and high-volatility commercial real estate (HVCRE). At this point, we note that land financing and acquisition, development and construction (ADC) are used in banks as HVCRE (Li and Chen 2013).

This paper focuses on a case of a slotting model for specialized lending exposures in real estate. Table 1 provides an overview of the two types of real estate exposures (IPRE and HVCRE) and details their key differences.

Table 1: Description of real estate project types. [This table provides an overview of the two types of real estate exposures: income-producing real estate (IPRE) and high-volatility commercial real estate (HVCRE).]
IPRE HVCRE

 Loan repayment depends

 primarily on the cashflow

 generated by the financed

 project

 Cashflows stem primarily from

 the lease, rental income or sale

 of the project

 The borrower may be an SPE or

 an operating company with

 additional sources of revenue

 Loan repayment is not certain

 Cashflows stem primarily from

 the future sale of the project

 The loan serves to finance land

 acquisition, development and

 construction phases

This paper recognizes two problematic areas stemming from the lack of detailed regulatory guidance for the categorization of the specialized lending exposures. First, distinguishing real estate projects that should not be classified as specialized lending (Giannotti et al 2011) remains especially problematic. Second, it is difficult to assign a real estate specialized exposure to either the IPRE category or HVCRE category. These difficulties arise from the fact that banks often issue a completion guarantee that provides the buyer of a property under construction with an assurance that the work will be completed should the developer default (Skibniewski 2014). The completion guarantee is not an investment loan, but it is treated as a credit line.

To aid practitioners in determining which real estate projects should be treated as specialized lending, Table 2 presents several scenarios in which a real estate project can be easily misclassified as specialized lending. These scenarios serve as lessons for credit risk analysts. An especially problematic case may arise from the situation where a borrower (an SPE) runs several projects. Although there is no regulatory rule for the determination of the specialized lending status in this case, any bank should carefully assess the degree of diversification of the projects and the capacity to replace the income generated by the obligor’s assets with other incomes of the obligor.

Table 2: Examples of specialized lending classification for real estate projects. [This table presents several scenarios where a real estate project can easily be misclassified as specialized lending.]
    SLE Project
Scenario Example classification type
001

A bank makes a loan to an SPE to finance the construction of an office building that will be rented out upon completion. The SPE has no other assets and has been created solely to manage this office building.

Yes IPRE
002

A bank makes a loan to a large, well-diversified operating company to finance the construction of an office building that will be primarily occupied by the company. The office building is pledged as collateral on the loan. The loan is small relative to the overall assets and debt service capacity of the company.

No Corporate
003

A bank makes a loan to an operating company to finance the construction or acquisition of an office building that will be let to tenants. The office building is pledged as collateral on the loan, and the loan is a general obligation of the company. The company has essentially no other assets. The bank underwrites the loan using its corporate procedures.

Yes IPRE
004

A bank makes a loan to an operating company to finance the construction or acquisition of an office building that will be let to tenants. The company has essentially no other assets. The bank underwrites the loan using its corporate procedures. The loan is unsecured.

Yes IPRE
005

A bank makes a loan to an SPE to finance the acquisition of an office building that will be primarily leased to a large, well-diversified operating company under a long-term lease. The SPE has no other assets and has been created solely to manage this office building. The lease is at least as long as the loan term and is noncancelable. The loan is amortized fully over the term of the lease with no bullet or balloon payment at maturity.

No Corporate
006

A bank makes a loan to an SPE to finance the acquisition of an office building that will be primarily leased to a large, well-diversified operating company under a long-term lease. The lease term can be canceled at some time before the end of the loan term.

Yes IPRE
007

A bank makes a loan to an SPE to finance the acquisition of an office building that will be primarily leased to a large, well-diversified operating company under a long-term lease. The lease in noncancelable, but the lease payments do not fully cover the aggregate loan payments over the life of the loan.

Yes IPRE
008

A bank makes a loan to the owner-occupied construction project, provided that the owner (borrower) has sufficient capacity at origination to repay the loan from an ongoing operation.

No Corporate
009

A bank makes a loan to the partially owner-occupied construction project. One-half (or more) of the primary source of repayment is derived from a third-party.

Yes IPRE
010

A bank makes a loan with direct recourse on another entity (full or limited recourse) that allows the bank to collect from the debtor’s other assets in the case of default as opposed to foreclosing on a particular property or asset.

No Corporate

Summarizing Table 2 in light of the limited regulatory guidance, we suggest the following determinants of the specialized slotting categorization.

Materiality of the obligor’s cashflows:

a bank should assess if other activities of the obligor are significant and if the obligor can substitute any cashflow. We point to the 30% substitution coverage threshold used in the industry. Therefore, the ability of the obligor to sufficiently substitute any failed cashflow (above 30%) as a source of payment should be taken into account when determining the corporate status.

Materiality of the bank financing:

a bank should check whether the obligor uses more than one line of credit from the bank, as several credit products are commonly offered to the same obligor. At this point, the predominant nature of the credit product is key in determining the exposure categorization. The obligor can be assigned only to one category based on the predominant credit line.

To determine the real estate specialized exposure type (IPRE versus HVCRE), we suggest following the purpose of the credit. For the HVCRE type, the following types of credit are appropriate: land financing without a general plan of the layout; and real estate with a particular layout plan; real estate with a construction permit. For the IPRE type, the following type of credit is appropriate: investment loans to income-producing real estate.

2.2 Real estate slotting approach

This section presents a standard risk-weight-based slotting approach to modeling the IPRE real estate exposures. Pursuant to Article 153(5) of the CRR, the risk weights are based on the remaining maturity of the exposure and the strength of the real estate project indicated by a slotting category, as shown in Table 3.

Table 3: Imposed RWA parameters and real estate project maturities (%). [This table presents a standard risk-weight-based slotting approach to modeling the real estate exposures. *The average maturity is obtained from the data of a real estate portfolio (116 projects) of a universal bank in the Czech Republic.]
    Category
Remaining Average  
maturity maturity* 1 2 3 4 5
(years) (years) (strong) (good) (satisfactory) (weak) (default)
< 2.5 1.25 50 70 115 250 0
 2.5 3.00 70 90 115 250 0

The IPRE real estate exposures are assigned to a single category upon calculating the scores of the following regulatory-prescribed factors.

Financial strength.

This factor looks at market conditions, financial ratios, loan-to-value (LTV) ratios, cashflow predictability and the ability of the project to survive stress conditions (cashflow reduction and interest rates increase).

Political and legal environment.

This factor analyzes whether the jurisdiction supports the repossession and enforcement of contracts as well as the political risk and transfer risk.

Transaction and/or asset characteristics.

This factor looks at the quality of the location, design and condition of the property as well as the financial structure (amortization schedule and refinancing risk).

Strength of the sponsor and developer.

This factor looks at the financial capacity of, and willingness by, the sponsor/developer to support the project together with their management experience, as well as the relationships between relevant real estate actors (eg, promoters).

Security package.

This factor looks at the nature of lien (a credit institution having the first claim on the debt) and the quality of the insurance coverage for the project.

As noted by Pitschke and Bone-Winkel (2006), the slotting model for real estate specialized lending exposures falls under the remit of the IRB framework, which is currently being reviewed by the European Banking Authority (EBA). Therefore, the final regulatory-prescribed standards for the slotting approach may, in the near future, be subject to changes that reflect the ongoing efforts to minimize the interference of the credit risk models with IFRS 9. The EBA has already expressed its expectations for the maximization of the synergy between the IRB credit risk models and the IFRS 9 requirements (European Banking Authority 2016a). At this point, a slotting model that does not produce PD estimates is in conflict with the regulatory push for minimizing the divergence between the IRB and IFRS 9 frameworks.

According to Jankowitsch et al (2007), this type of credit risk model is used when the PD cannot be estimated easily. The slotting approach determines regulatory capital based on the final slotting score assigned to the real estate project. The EBA specifically dictates the way of assigning risk weights to specialized lending exposures for which an institution is not able to estimate PDs. With this in mind, Scannella (2013) argues that this regulatory-prescribed way of developing a slotting model constrains the methodological choices, and Akkizidis and Kalyvas (2018) point to the elevated levels of risk-weighted capital stemming from the use of the regulatory-prescribed methodology. In a study covering 3442 UK IPRE projects, Frodsham and Gimblett (2012) pointed out that in some simulated cases the risk-weighted capital mandated for the “strong” and “good” slotting categories is well in excess of downturn LGD. Focusing on the UK IPRE projects, Frodsham and Gimblett also pointed to the fact that the implementation of the EBA’s slotting methodology by the local regulator is not consistent with the leasing norms in the United Kingdom.

In summary, the slotting approach outlined by the EBA has been heavily criticized by both practitioners and academics for its methodological weaknesses. Pinsent Masons (2012) suggested that the use of slotting models might discourage lending to real estate projects. Finally, Ranson (2006) stated that the limited number of slots and the lack of predefined weights for the slotting factors do not capture credit risk adequately. Thus, the slotting approach has been avoided by credit institutions and has not received significant attention in academic studies, which focus primarily on PD modeling. However, we recognize that the potential attractiveness of using the slotting approach in IPRE and HVCRE projects lies in the simplicity of the model implementation. As noted by Abdou and Pointon (2011), a real estate slotting model is often implemented as a Microsoft Excel scorecard filled in by the analysts using their expert judgment. Thus, it is easier to validate or backtest this type of model. Table 4 presents a general methodology of a real estate slotting approach indicating where the expert judgment is used.

Table 4: Slotting approach methodology. [This table presents the hierarchy (left to right) for the general methodology of a real estate slotting approach in assigning a final slotting score, indicating where expert judgment is used. DSCR, debt service coverage ratio. ICR, interest coverage ratio.]
EBA’s EBA’s Bank’s individual
factors subfactors variables
Financial Market Vacancy rate
strength conditions Expert judgment
  Financial ratios DSCR
    ICR
    Profit margin
  LTV Current LTV
  Stress analysis DSCR after:
      increase in interest rates
      cashflow reduction
    ICR after: cashflow reduction
    Profit margin after:
      increase in construction costs
      decrease in the sale value
  Cashflow predictability Expert judgment
    Net rental income
    Remaining lease
    Selling price
    Other quantitative analyses
Political and Legal and regulatory Expert judgment
legal Political Expert judgment
Asset Location Expert judgment
characteristics Design and condition Expert judgment
  Property under construction Expert judgment
  Financial structure Expert judgment
    Bullet repayment
    (amortizing debt)
Strength of Financial capacity LTV at origination
sponsor   Expert judgment
  Reputation and track record Expert judgment
  Relationship with Expert judgment
  real estate actors  
Security Nature of lien Collateral type
package   First lien
  Assignment of rent Expert judgment
    Percentage of rent assignment
  Quality of insurance Expert judgment

This paper is built on the assumption that the most material problems of the slotting approach refer to the IFRS 9 requirements rather than the limited regulatory guidance on factor risk weights or methodological inconsistencies. We posit that the slotting model has to be developed in line with the regulator-dictated methodological choices (EBA’s regulatory technical standards (RTS)) that limit pursuing alternative methodologies. Therefore, challenging the regulatory choices remains counterintuitive for a credit institution compelled to follow specific methodological pathways. A bank cannot choose not to include certain regulatory-prescribed factors or choose to use variables that are not aligned to the factor descriptions provided by the EBA.

2.3 IFRS 9

IFRS 9 introduces the concept of staging when assessing a significant increase in credit risk. The concept is outlined in Paragraph 5.5.5 of the IFRS 9 regulation, which requires the measurement of the loss allowance on a 12-month expected credit loss basis if there is no significant increase in credit risk. Determining the significant increase in risk is done at each reporting stage (Ozdemir 2018). Pursuant to Paragraph 5.5.9 of the IFRS 9 regulation, the bank is then required to assess whether the credit risk on a financial instrument has increased substantially since the initial reporting. The IFRS 9 framework specifically stipulates that the assessment should be based on the changes to default risk occurring over the expected life of the financial instrument (Chawla et al 2016). According to Memmel et al (2015), this approach becomes problematic for models that do not provide a granular distinction between default rates. Against this backdrop, our paper provides a possible solution for the assessment of any significant increase in the credit risk of the slotting model without undue cost or effort.

As indicated in Paragraph B5.5.5 of IFRS 9, any significant increase in credit risk should be assessed of on the basis of shared credit risk characteristics with the objective of facilitating an analysis designed to identify a significant increase in credit risk on a timely basis (Beerbaum 2015). Although the IFRS 9 rules allow both qualitative and nonstatistical quantitative information to be used to determine whether a significant increase in credit risk occurred, Miihkinen (2012) argues against using expert judgment in the assessment. In a nutshell, the following criteria can be used for the staging process.

Stage 1:

credit risk has not increased significantly since the initial recognition. The loss allowance is equal to the 12-month ECL.

Stage 2:

credit risk has increased significantly since the initial recognition. The loss allowance is equal to the lifetime ECL. It can be measured by a significant downgrade in the rating master scale since the initial recognition, which refers to denotching.

Stage 3:

credit risk has increased to the point that credit impairment has occurred.

As a quantitative measure of the significant increase in credit risk, we point to the methodology based on the internal rating downgrades (denotching). This approach follows the guidelines outlined in Paragraph B5.5.16 of IFRS 9. Thus, the measurement of any significant increase in credit risk involves comparing ratings or slotting scores at different points in time. As noted by Vlachostergios (2017), other factors considered in the IFRS 9 staging process relate to default indicators such as the forbearance and past due days. Leventis et al (2011) highlights emerging problems linked to the financial asset classification using the IFRS 9 staging process. These problems are related to the measurement of a significant deterioration in credit risk, which implies that credit risk models should reconsider the risk of default measured as the probability of default (PD). Figure 1 shows the IFRS 9-aligned staging process.

IFRS 9 staging process.
Figure 1: IFRS 9 staging process.

The key differences between the principles of the IFRS 9 and the EBA’s RTS lie within the regulatory objectives of the two components. The IFRS 9 is focused on ensuring accuracy in the estimation of the risk-weighted assets (RWA). In doing so, IFRS 9 would allow for individually tailored approaches to modeling specialized lending exposures. On the other hand, the overarching principle of the EBA’s RTS is to ensure the harmonization of risk management and calculation of risk-weighted exposures across credit institutions. In this vein, the slotting approach does not allow additional flexibility and is centered on retaining the conservatism in the risk estimates at the cost of the accuracy.

Complementing Figure 1, we point out some common problems dominating the slotting models. Due to the limited number of regulatory-prescribed slotting categories for credit risk, it remains difficult to justify the denotching levels that would indicate a significant rating downgrade leading to stage 2 of the IFRS 9 loss recognition.

Onali and Ginesti (2014) point to the fact that the IFRS 9 accounting framework is based on principles introducing a logical model for classification and measurement of financial assets and liabilities. This is regarded by Ball (2006) as an important step toward simplifying the complex rules of International Accounting Standard 39. Further, as noted by Pool et al (2015), while changing the ways of hedge accounting, the IFRS 9 rules address the need for a forward-looking expected loss impairment model. Table 5 presents the IFRS 9 articles that relate specifically to the area of credit risk measurement and modeling.

Prorokowski (2018) points to the major differences between the IRB and IFRS 9 concepts relating to the PD/LGD framework. The slotting models have as yet received little academic attention. The IRB PD models are measured on a through-the-cycle basis, which reflects the cyclical nature of economic conditions (Carlehed and Petrov 2012). According to Edwards (2014), the IFRS 9 models should be point-in-time. However, in this paper we argue that the slotting approach satisfies the point-in-time criterion despite using some factors that may be regarded as idiosyncratic or lagged economic indicators. This is due to the fact that the slot categorization is made by the analyst based on the currently available data without the use of the through-the-cycle averaged factors. All in all, a review of existing studies suggests that the scholarly discussion on differences between the IRB and the IFRS 9 frameworks is limited to flagging conceptual discrepancies.

Table 5: IFRS 9 in credit risk modeling. [This table presents the IFRS 9 articles that specifically relate to the area of credit risk measurement and modeling.]
Article Article description Practical application
5.5.9

Upon reporting, the bank should check if the credit risk on a financial instrument increased significantly from the point of recognition. Instead of assessing the change in the severity of the expected credit losses, the bank should assess the change in the default probability occurring during the lifetime of the financial instrument.

The model output should be the default probability occurring during the lifetime of the financial instrument and should be sufficiently granular in order to measure an increase in credit risk. At specific points in time the ECL should be compared with the previous results. Thus, the slotting model should provide the estimates that are point-in-time and converted to PDs.

5.5.10

Under the exception rule, the bank can assume that the credit risk on a financial instrument has not increased significantly. This exception can be executed only if the financial instrument has low credit risk at the reporting date.

In practice, this exception can apply to the highly rated sovereign exposures but not to the specialized lending real estate exposures. Further, the BCBS guidance stresses that this exception should be used only in rare, exceptional circumstances. Therefore, an exposure falling in “category 1” of the slotting model at the reporting date does not render the assumption of no risk increase.

5.5.11

The bank cannot rely only on past information when determining whether the credit risk of a financial instrument has increased. The forward-looking information should be used for assessment purposes.

The forward-looking information can be used if it is readily available without undue cost in the case of the slotting approach to specialized lending exposures. There is an assumption that the significant increase in credit risk appears if the contractual payments are more than 30 days due. This enables any bank to recognize the credit risk increase in advance of the exposure becoming delinquent.

5.5.17

The ECL should reflect the following:

  • the unbiased and probability-weighted amount that stems from assessing a range of possible outcome scenarios;

  • the time value of money;

  • information about past events, current conditions and forecasts of future economic conditions.

The ECL calculation process should be unbiased (free of regulatory add-ons) and forward-looking. This creates problems for the slotting approach to real estate specialized lending exposures that is aligned to the regulatory-prescribed factors and subfactors.

5.5.19

The maximum period for the ECL is the maximum contractual period over which the bank is exposed to credit risk.

The maximum period for the ECL should not be longer than the time of exposure to credit risk. Thus, the ECL calculations need to incorporate the term structure.

As indicated in Table 5, the ECL estimation considers the following aspects.

Probability weighted amount:

the ECL cannot be based on either the worst- or best-case scenarios, or limited slots indicating the strength of the obligor and the project. The ECL should reflect the probability of a loss occurring during the lifetime of the financial instruments.

Time value of money:

the ECL should be discounted to the reporting date.

Required forward-looking information:

the ECL should use reasonable and supportable information that is accessible without undue cost. However, under the IRB framework, banks should not avoid excessive and unnecessary costs associated with obtaining the forward-looking information.

According to Miu and Ozdemir (2016), the conceptual differences boil down to the methodological approaches between the IFRS 9 compliant models and the IRB modeling. Interestingly, there is also a string of academic studies that investigate whether the existing IRB models can be reused for IFRS 9 purposes despite the compliance gaps. The current paper is partly rooted in this string of scholarly literature. In particular, we recognize the study of Reitgruber (2015), which argues that having the same suite of models satisfying both the IRB and IFRS 9 requirements allows for the consistency in the use of risk models to be retained. However, as noted by Marlin (2017), the process of adapting the existing credit risk models to the IFRS 9 requirements remains challenging due to the need for significant adjustment of the data underpinning the PD and LGD models. With this in mind, we assume the adjustments extend beyond the data to the model outputs in the case of the slotting approach to specialized lending.

3 Methodology

3.1 Model description

The model used in this exercise is a slotting scorecard for specialized lending exposures developed and implemented in October 2018 by a universal bank (ie, a domestic systemically important bank) domiciled in the Czech Republic. The model constitutes a significant component of the bank’s rating process for the IPRE and HVCRE projects. The scorecard generates a supervisory category rating (score) that is used to assign a real estate project to the slotting categories. The model and the corresponding rating system passed the initial validation in November 2018. The initial validation covers the following areas.

Model design.

This focuses on the scope, consistency of the perimeter, model history, regulatory compliance checks and documentation review.

Impact analysis.

This focuses on the EAD and RWA impact assessment and result improvements.

Portfolio analysis.

This focuses on model materiality and portfolio characteristics as well as missing values and data errors.

Default definition.

This focuses on the consistency of the implemented default in the systems.

Databases and systems.

This focuses on the data quality process and BCBS 239 (Basel Committee on Banking Supervision 2013) compliance.

Model methodology.

This describes the modeling choices and replicating the model.

Model performance.

This focuses on benchmarking and robustness checks as well as calibration and discrimination tests.

Implementation.

This focuses on the process for implementation of the scorecard.

Use test.

This focuses on model use within the bank.

Governance.

Gathering stakeholders’ feedback and providing a model risk rating.

The model was developed with the aim of replicating the EBA recommendations outlined in European Banking Authority (2016b) with the designation for the commercial real estate loan origination business (IPRE and HVCRE projects). As already discussed in this paper, the EBA’s final draft RTS document specifies how credit institutions should incorporate the credit risk factors into their model when assigning risk weights to specialized lending exposures. Therefore, the model consists of five specific factors characterizing a real estate exposure, and each factor contains several subfactors of a qualitative and quantitative nature.

Table 6: Model design. [This table presents the five specific factors and their underlying subfactors that lead to the final slotting score characterizing a real estate exposure.]
Factor Subfactors
I Financial strength Market conditions
    financial ratios
    Advance ratio
    Stress analysis
    Cashflow predictability
II Political and legal environment Legal and regulatory risks
    Political risk
III Asset and transaction characteristics Location
    Design and condition
    Financial structure
IV Strength of sponsor or developer Financial capacity
    Reputation and track record
    Relationships with relevant actors
V Security package Nature of lien
    Assignment of rents
    Quality of insurance coverage

Complementing Table 6, we acknowledge that it is necessary to have a multitude of factors and subfactors in order to capture all the major risk drivers. We also note that the specification of the factors and subfactors has no major deviations from the EBA’s RTS. Each factor leading to the final slotting score is assigned an individual weight at the bank participating in this study by submitting its slotting model.

3.2 Rating process

Table 7: Rating process. [This table presents the slotting categories divided into five rating categories following compliance with the relevant regulations.]
Slotting EBA Final slotting  
category designation score, s Description/meaning
1 Strong 1.00s<1.50
  • The project is able to generate stable cashflows and remains highly competitive

  • The sponsor has superb financial strength and the obligor can meet its financial obligations in times of significant stress

  • There is a comprehensive security package in place]

2 Good 1.50s<2.50
  • The project is able to generate adequate and stable cashflows and remains competitive

  • The sponsor has good financial strength, but the obligor may not fully meet its financial obligations in times of significant stress

  • There is a comprehensive security package in place

3 Satisfactory 2.50s<3.50
  • The project is able to generate stable cashflows, but is moderately competitive in the market

  • The sponsor has moderate financial strength and the obligor’s ability to survive a period of significant stress is weak

  • There are defects in the security management, which may lead to cashflow disruptions

4 Weak 3.50s<4.00
  • The project is at risk of not generating cashflows and is not competitive in the market

  • The sponsor has poor financial strength and the obligor cannot survive in times of significant stress

5 Default “Default”
  • The definition of default is used as defined in Article 178 of the CRR (European Union 2013)

The rating is the final slotting score, which allows a real estate project to be assigned to one of five distinct categories. All rating inputs are based on the expert judgment of the real estate analyst populating the scorecard. Each subfactor has underlying variables that are used by the real estate analyst, who has substantial knowledge about the evaluated real estate project and the obligor. The quantitative variables are based on the most recent financial statements of the obligor and the project, external independent property valuation reports and other publicly available information (eg, market reports). The ratings are then validated and approved by the credit officer under the “four-eyes principle” described by Hiebl (2015).

Table 7 presents the slotting categories, which are divided into five rating categories following the compliance with the EBA’s RTS. We note that the assignment of a project to the fifth slotting category (“default”) does not depend on the scorecard results, and hence does not follow the standard rating process, but is done manually by the credit risk analyst.

Complementing Table 7, we note that each factor leading to the final slotting score was assigned an individual weight by the bank participating in this study. The factors are aggregated to arrive at the final slotting score, which is used to determine the slotting category.

3.3 Data

The data was provided by the bank participating in this exercise. It contains the metadata items around the model output (Table 8).

Average maturity:

the average remaining maturity of the real estate specialized lending project aligned to Article 153(5) of the CRR.

Target RWA:

the regulatory-prescribed risk weight threshold aligned to Article 153(5) of the CRR.

Target EL:

the ratio of the expected loss (EL) assigned to the slotting categories by the bank participating in the study.

PD master scale:

the rating scale for midcorporate PDs used by the bank participating in the study. The PD master scale contains regulatory PDs and PDs used by the bank for the midcorporate portfolio of obligors.

Table 8: Metadata description. [This table presents the metadata items around the model output. All values in parts (a)–(d) are percentages. SC, slotting category.]
(a) PD master scale (regulatory PDs)
AAA AA+ AA AA- A+ A A- BBB+ BBB
0.06 0.09 0.13 0.20 0.29 0.42 0.61 0.89 1.30
BBB- BB+ BB BB- B+ B B- CCC D
1.90 2.78 4.06 5.94 8.67 12.67 18.51 27.04 100.00
(b) PD master scale (midcorporate PDs)
AAA AA+ AA AA- A+ A A- BBB+ BBB
0.00 0.02 0.03 0.04 0.05 0.06 0.07 0.18 0.34
BBB- BB+ BB BB- B+ B B- CCC D
0.71 0.88 1.15 2.68 3.95 9.07 13.84 30.87 100.00
(c) Target RWA
Remaining maturity (years) SC1 SC2 SC3 SC4 SC5
M<2.5 50 70 115 250 00 (default)
M2.5 70 90 115 250 00 (default)
(d) Target EL
Remaining maturity (years) SC1 SC2 SC3 SC4 SC5
M<2.5 0 0.4 2.8 8.0 50
M2.5 0.4 0.8 2.8 8.0 00 (default)
(e) Average maturity (years)
  SC1 SC2 SC3 SC4 SC5
  1.25 1.25 3 3 3

As shown in Table 8, the slotting approach to modeling the credit risk of real estate specialized lending pushes banks (including the bank participating in this study) to develop a discrete classification of specialized exposures. In doing so, banks need to comply with the regulatory framework of assigning risk weights and EL values as directed by Articles 153(5) and 158(6) of the CRR. In the PD mapping methodology proposed in this paper, the following data items are considered:

  • target RWA,

  • target EL and

  • average maturity.

3.4 PD mapping methodology

This section describes the methodology for deriving the correspondence between the four slotting categories (the “default” category is ignored) and the rating scale that quantitatively reflects the default risk of a particular obligor. To maximize practical implementation, the methodology uses a realistic rating scale for midcorporate obligors applied by the bank participating in this study. Further, the proposed methodology is based on the regulatory-prescribed formulas for risk weights and EL. We recognize the following benefits of the aforementioned methodological assumptions:

  1. (1)

    The methodology yields a more granular scale for evaluating credit risk at an obligor-level and enables a more practical implementation of the IFRS 9 denotching mechanism.

  2. (2)

    The methodology satisfies IFRS 9 requirements for the measurement of cumulative default probabilities over a given forecasting horizon.

  3. (3)

    The methodology satisfies IFRS 9 requirements for the assessment of a significant increase in credit risk, which is an essential component of the IFRS 9 framework.

The proposed mapping methodology is a sequential process. At the starting point, both the target RWA and target EL are considered. These perimeters are derived from the regulatory-prescribed formulas and are constructed around the primary credit risk indicators: the probability of default and the loss given default. The proposed methodology serves to identify PD and LGD values by solving the following simultaneous equations:

  mapping={RWAT=f(PD,LGD,R(PD),b(PD),M),ELT=g(PD,LGD),   (3.1)

where R(PD) is the correlation coefficient and b is the maturity adjustment factor. Both R and b are endogenous variables dependent on the PD. M is the maturity of the exposure to the real estate project. The above coefficients are derived from the regulatory-prescribed formulas:

  R =0.121-e-50PD1-e-50+0.24(1-1-e-50PD1-e-50PD),   (3.2)
  b =(0.11852-0.05478ln(PD))2.   (3.3)

The target RWA and target EL are derived from the following formulas:

  RWAT =(LGD×N(11-RG(PD)+R1-RG(0.999))-LGD×PD)  
      ×1+(M-2.5)b1-1.5b×12.5×1.06,   (3.4)
  ELT =PD×LGD.   (3.5)

Since the real estate specialized lending exposures are assigned to four distinct slotting categories, we should solve (3.1) for each slotting category. Moreover, real estate projects are differentiated by the maturity thresholds in the regulatory framework. Therefore, the mapping determines two sets of solutions, with the first being for the fixed average maturity of 1.25 years and the second for the fixed average maturity at 3 years.

4 Analysis and findings

4.1 PD mapping to slotting categories

First, on solving (3.1), the PDs and LGDs are obtained for each final slotting score. This procedure tests the following LGD values to obtain the PDs: 50%, 45%, 40%, 35%, 30%, 25%, 20%, 15%, 10%, 5%.

Table 9: Solving for PDs (M=1.25; α=99.9%). [This table shows different PDs assigned to the slotting categories for a maturity of 1.25 years. SC, slotting category.]
SC LGD PD VaR ???-?? RWA ???? CE
1 50 00.3 03.93 03.76 050 050 000
1 45 00.4 03.96 03.78 050 050 000
1 40 00.5 04.00 03.79 050 050 000
1 35 00.7 04.05 03.81 050 050 000
1 30 01.0 04.12 03.83 050 050 000
1 25 01.5 04.24 03.86 050 050 000
1 20 03.0 04.48 03.89 050 050 000
1 15 06.6 04.90 03.92 050 050 000
1 10 19.8 05.94 03.95 050 050 000
1 05 30.7 03.64 02.10 026 050 024
2 50 00.7 05.66 05.33 070 070 000
2 45 00.8 05.72 05.35 070 070 000
2 40 01.1 05.80 05.37 070 070 000
2 35 01.5 05.93 05.40 070 070 000
2 30 02.4 06.15 05.43 070 070 000
2 25 04.1 06.50 05.47 070 070 000
2 20 07.4 06.97 05.50 070 070 000
2 15 15.5 07.85 05.53 070 070 000
2 10 30.7 07.27 04.20 053 070 017
2 05 30.7 03.64 02.10 026 070 044
3 50 02.3 10.07 08.92 115 115 000
3 45 03.2 10.38 08.95 115 115 000
3 40 04.5 10.77 08.99 115 115 000
3 35 06.3 11.23 09.02 115 115 000
3 30 09.2 11.80 09.04 115 115 000
3 25 14.8 12.78 09.08 115 115 000
3 20 30.7 14.55 08.40 106 115 009
3 15 30.7 10.91 06.30 079 115 036
3 10 30.7 07.27 04.20 053 115 062
3 05 30.7 03.64 02.10 026 115 089
4 50 19.8 29.68 19.77 250 250 000
4 45 30.7 32.73 18.90 238 250 012
4 40 30.7 29.09 16.80 212 250 038
4 35 30.7 25.46 14.70 185 250 065
4 30 30.7 21.82 12.60 159 250 091
4 25 30.7 18.18 10.50 132 250 118
4 20 30.7 14.55 08.40 106 250 144
4 15 30.7 10.91 06.30 079 250 171
4 10 30.7 07.27 04.20 053 250 197
4 05 30.7 03.64 02.10 026 250 224
Table 10: Solving for PDs (M=3; α=99.9%). [This table shows different PDs assigned to the slotting categories for a maturity of three years. SC, slotting category.]
SC LGD PD VaR ???-?? RWA ???? CE
1 50 00.3 03.87 03.70 070 070 000
1 45 00.4 03.99 03.80 070 070 000
1 40 00.6 04.14 03.92 070 070 000
1 35 00.8 04.33 04.06 070 070 000
1 30 01.2 04.60 04.23 070 070 000
1 25 02.3 05.06 04.48 070 070 000
1 20 05.2 05.78 04.75 070 070 000
1 15 11.7 06.75 04.99 070 070 000
1 10 29.2 07.11 04.19 056 070 014
1 05 29.2 03.56 02.10 028 070 042
2 50 00.6 05.37 05.07 090 090 000
2 45 00.8 05.56 05.21 090 090 000
2 40 01.1 05.82 05.39 090 090 000
2 35 01.7 06.20 05.61 090 090 000
2 30 03.0 06.79 05.88 090 090 000
2 25 05.6 07.55 06.14 090 090 000
2 20 10.5 08.49 06.38 090 090 000
2 15 29.2 10.67 06.29 084 090 006
2 10 29.2 07.11 04.19 056 090 034
2 05 29.2 03.56 02.10 028 090 062
3 50 01.2 07.51 06.93 115 115 000
3 45 01.6 07.89 07.15 115 115 000
3 40 02.6 08.45 07.42 115 115 000
3 35 04.2 09.17 07.70 115 115 000
3 30 06.7 09.97 07.94 115 115 000
3 25 11.2 10.99 08.18 115 115 000
3 20 29.2 14.22 08.39 112 115 003
3 15 29.2 10.67 06.29 084 115 031
3 10 29.2 07.11 04.19 056 115 059
3 05 29.2 03.56 02.10 028 115 087
4 50 14.5 25.31 18.04 250 250 000
4 45 35.1 34.56 18.78 250 250 000
4 40 29.2 28.45 16.78 225 250 025
4 35 29.2 24.89 14.68 197 250 053
4 30 29.2 21.34 12.58 169 250 081
4 25 29.2 17.78 10.48 141 250 109
4 20 29.2 14.22 08.39 112 250 138
4 15 29.2 10.67 06.29 084 250 166
4 10 29.2 07.11 04.19 056 250 194
4 05 29.2 03.56 02.10 028 250 222

The first step involves fixing the average maturity to 1.25 years and 3 years, testing for the fixed LGDs and setting the targets for the RWA and EL values (as prescribed by the regulator). Tables 9 and 10 show the different PDs assigned to the slotting categories. The aim of this exercise is to satisfy the target RWA (RWAT) with the lowest calibration error (CE) possible and then to satisfy the following conditions for the EL:

  CE =RWAT-RWA,   (4.1)
  VaR-EL =VaR-(LGD×PD),   (4.2)

where VaR denotes value-at-risk.

Table 11: Master scale (the same for all values of M). [This table shows the derivation of the PD master scale for different maturity levels. SC, slotting category.]
      Corresponding master
  PD (%) scale grade
     
  ?<2.5 ?2.5 Regulatory Midcorporate
SC (1.25Y) (1.25Y) scale portfolio scale
1 00.3 00.3 A+ BBB
2 00.7 00.6 A- BBB-
3 02.3 01.2 BB+ BB-
4 19.8 14.5 B- B-

A visual inspection of these tables reveals that the conditions for the target RWA and the minimum difference between VaR and the EL are satisfied for the subsequent PDs, presented in Table 11.

We now make several important remarks summarizing Tables 911. First, in all cases, the LGD=50%, which makes it a constant parameter. Second, the granularity of the ratings is limited and there are several ratings missing between the values provided. Third, using the PD master scale for the midcorporate portfolio yields more realistic results and is also justified by the fact that the real estate specialized lending exposures usually stem from the midcorporate obligor class (Mondal 2011).

Finally, solving for (3.1) requires the conditions for the target RWA and target EL to be satisfied simultaneously. Table 12 shows the optimal PDs mapped to the slotting categories for a maturity M=1.25 years. A similar process is carried out for M=3 years.

Table 12: Solving for optimal PDs (M=1.25 years; α=99.9%). [This table shows the optimal PDs mapped to the slotting categories (SCs) for a maturity of 1.25 years.]
            Target Target   Target  
SC LGD (%) PD (%) VaR (%) ???-?? (%) RWA (%) RWA (%) cal. (%) EL (%) EL (%) Error (%)
1 50 00.3 03.93 03.76 050 050 000 00.2 0.0 -0.2
1 45 00.4 03.96 03.78 050 050 000 00.2 0.0 -0.2
1 40 00.5 04.00 03.79 050 050 000 00.2 0.0 -0.2
1 35 00.7 04.05 03.81 050 050 000 00.2 0.0 -0.2
1 30 01.0 04.12 03.83 050 050 000 00.3 0.0 -0.3
1 25 01.5 04.24 03.86 050 050 000 00.4 0.0 -0.4
1 20 03.0 04.48 03.89 050 050 000 00.6 0.0 -0.6
1 15 06.6 04.90 03.92 050 050 000 01.0 0.0 -1.0
1 10 19.8 05.94 03.95 050 050 000 02.0 0.0 -2.0
1 05 30.7 03.64 02.10 026 050 024 01.5 0.0 -1.5
2 50 00.7 05.66 05.33 070 070 000 00.3 0.4 -0.1
2 45 00.8 05.72 05.35 070 070 000 00.4 0.4 -0.0
2 40 01.1 05.80 05.37 070 070 000 00.4 0.4 -0.0
2 35 01.5 05.93 05.40 070 070 000 00.5 0.4 -0.1
2 30 02.4 06.15 05.43 070 070 000 00.7 0.4 -0.3
2 25 04.1 06.50 05.47 070 070 000 01.0 0.4 -0.6
2 20 07.4 06.97 05.50 070 070 000 01.5 0.4 -1.1
2 15 15.5 07.85 05.53 070 070 000 02.3 0.4 -1.9
2 10 30.7 07.27 04.20 053 070 017 03.1 0.4 -2.7
2 05 30.7 03.64 02.10 026 070 044 01.5 0.4 -1.1
3 50 02.3 10.07 08.92 115 115 000 01.1 2.8 -1.7
3 45 03.2 10.38 08.95 115 115 000 01.4 2.8 -1.4
3 40 04.5 10.77 08.99 115 115 000 01.8 2.8 -1.0
3 35 06.3 11.23 09.02 115 115 000 02.2 2.8 -0.6
3 30 09.2 11.80 09.04 115 115 000 02.8 2.8 -0.0
3 25 14.8 12.78 09.08 115 115 000 03.7 2.8 -0.9
3 20 30.7 14.55 08.40 106 115 009 06.1 2.8 -3.3
3 15 30.7 10.91 06.30 079 115 036 04.6 2.8 -1.8
3 10 30.7 07.27 04.20 053 115 062 03.1 2.8 -0.3
3 05 30.7 03.64 02.10 026 115 089 01.5 2.8 -1.3
4 50 19.8 29.68 19.77 250 250 000 09.9 8.0 -1.9
4 45 30.7 32.73 18.90 238 250 012 13.8 8.0 -5.8
4 40 30.7 29.09 16.80 212 250 038 12.3 8.0 -4.3
4 35 30.7 25.46 14.70 185 250 065 10.8 8.0 -2.8
4 30 30.7 21.82 12.60 159 250 091 09.2 8.0 -1.2
4 25 30.7 18.18 10.50 132 250 118 07.7 8.0 -0.3
4 20 30.7 14.55 8.40 106 250 144 06.1 8.0 -1.9
4 15 30.7 10.91 6.30 079 250 171 04.6 8.0 -3.4
4 10 30.7 07.27 4.20 053 250 197 03.1 8.0 -4.9
4 05 30.7 03.64 2.10 026 250 224 01.5 8.0 -6.5
Satisfying target RWA. This figure shows the combination of PDs and LGDs satisfying the target RWA.
Figure 2: Satisfying target RWA. This figure shows the combination of PDs and LGDs satisfying the target RWA.

Solving for the optimal PDs reveals that the optimal PDs differ from the mapped PDs at the fixed LGD level (LGD=50%). At this point, fixing the LGD at 50% leads to an increase in the calibration error for the EL in slotting categories 2 and 3 for both cases with average maturity. Figure 2 shows the combination of PDs and LGDs satisfying the target RWA.

4.2 PD mapping to slotting scores

As mentioned in the previous section, solving for (3.1) is inefficient, as it leaves limited a granularity of the ratings. The case of ratings missing between the reported ratings should be addressed. This involves retrieving the scores associated with the missing ratings by using the resolution of a third-order polynomial. Once the PD values have been obtained for the slotting categories, we seek the correspondence with the PD master scale. This is done by starting with the PD value and finding the corresponding final slotting score:

  ln(PD(x))=a3x3+a2x2+a1x+a0,   (4.3)

where x (x(1,4]) denotes the slotting score. By using the bank’s PD master scale for midcorporate obligors in combination with the third-order polynomial, the missing scores can be obtained using Excel Solver.

In the first step, for the LGD fixed at 50%, the process of reconciling the content of Table 9 with the polynomial fitting using the function for the matrix product of two arrays is initiated. This leads us to obtain interim base PDs corresponding to the slotting scores 1, 2, 3 and 4, respectively. Appendix A online shows the results of solving for the polynomial fitting. The following correspondence is established.

  • For M=1.25: -5.67 for a slotting score of 1; -5.03 for a slotting score of 2; -3.78 for a slotting score of 3; and -1.62 for a slotting score of 4.

  • For M=3: -5.69 for a slotting score of 1; -5.12 for a slotting score of 2; -4.46 for a slotting score of 3; and -1.92 for a slotting score of 4.

Having the interim PDs as a starting point and using the third-order polynomial function (4.3), we find the following slotting scores. This process is the inverse of the function for obtaining PDs, as the resolution starts with a given PD value.

Appendix A online shows the results for the corresponding slotting scores. At this point, the interim PDs should be converted into final PDs. This is done using the exponential function,

  xex,   (4.4)

where x is the interim PD obtained by the polynomial fitting and matched with a corresponding slotting score. Using the results in Table A4 of Appendix A online, more granular PD parameters can be assigned to the corresponding slotting scores, as shown in Table 13.

Table 13: Slotting score mapping (PD and rating). [This table presents the granular PD parameters assigned to the corresponding slotting scores.]
?=1.25 years ?=? years
   
Cat LGD (%) PD (%) Rating Cat LGD (%) PD (%) Rating
1.00 50 00.34 BBB 1.00 50 00.34 BBB
2.00 50 00.65 BBB- 2.00 50 00.59 BBB-
2.30 50 00.88 BB+ 2.75 50 00.88 BB+
2.53 50 01.15 BB 3.00 50 01.16 BB
3.00 50 02.29 BB- 3.47 50 02.68 BB-
3.30 50 03.95 B+ 3.62 50 03.95 B+
3.69 50 09.07 B 3.88 50 09.07 B
4.00 50 19.81 B- 4.00 50 14.54 B-

On achieving a more granular rating correspondence between the slotting scores and mapped PDs, the last step involves defining both the lower and upper limits for each slotting category (Table 14).

Table 14: Slotting score mapping to PDs and ratings. [This table presents the lower and upper limits for each slotting category mapped to the PD estimates.]
?=1.25 years ?=? years  
     
    Lower Upper   Lower Upper
Rating PD (%) score score PD (%) score score
BBB 0.34 1.00 1.50 0.34 1.00 1.50
BBB- 0.65 1.50 2.15 0.59 1.50 2.38
BB+ 0.88 2.15 2.41 0.88 2.38 2.88
BB 1.15 2.41 2.76 1.16 2.88 3.23
BB- 2.29 2.76 3.15 2.68 3.23 3.54
B+ 3.95 3.15 3.50 3.95 3.54 3.75
B 9.07 3.50 3.85 9.07 3.75 3.94
B- 19.81 3.85 4.00 14.54 3.94 4.00

Complementing this table, we should note that the lowest mapping boundary is set to 1 and the highest mapping boundary is set to 4, owing to the alignment with the slotting model. Table 15 summarizes the rating assignments to different slotting categories.

Table 15: Slotting categories and mapped ratings. [This table summarizes the assignment of ratings to different slotting categories (SCs).]
    Mapped rating
     
SC Description ?=1.25 ?=?
1 Strong BBB BBB
2 Good BBB-, BB+, BB BBB-, BB+
3 Satisfactory BB, BB-, B+ BB+, BB, BB-
4 Weak B, B- BB-, B+, B, B-
5 Default

4.3 IFRS 9 implications

As highlighted in Section 1, the main aim of this paper is to map the slotting scores to PD estimates in order to deliver adequate inputs for the computation of the ECL. Specifically, our proposed solution meets the objective of measuring the IFRS 9 cumulative PD estimates:

  PDT=1-(1-PD1)T.   (4.5)

The availability of historical default data is limited for the newly developed slotting model. Thus, building the point-in-time parameters conditional on macroeconomic indicators remains counterintuitive. However, the cumulative PDs can be used by relying on basic assumptions specified in (4.5). Hence, a cumulative T-year PD estimate PDT is derived from the one-year PD together with the PD estimate, denoted PD1.

Converting the slotting scores into the ratings aids the denotching process under the IFRS 9 framework. As described by Honohan (2008), denotching is an automatic penalization of one notch for the estimate. This process is triggered if the obligor is not reevaluated within the 12-month period following the last rating/grading date. Without the increased granularity, the denotching process would be overly punitive for a bank relying on the four-point scale of the regulatory-prescribed slotting approach. However, with the mapped ratings in place, the impact of the denotching on the reported RWA and the EL is ameliorated, as evidenced in Table 16 for the example of an exposure with a maturity of 1.25 years.

Table 16: Denotching impact on RWA and EL with corresponding slotting score (maturity of 1.25 years). [This table presents the denotching impact on the reported RWA and the EL for a maturity of 1.25 years.]
  Initial point Denotching Impact Impact
Parameters (slotting score) (slotting score) on RWA on EL
Mapped rating BBB (1.20) BBB- (1.50)
Slotting category 1 2 Yes Yes
Mapped rating BBB- (1.50) BB+ (2.41)
Slotting category 2 2 No No
Mapped rating BB+ (2.41) BB (2.76)
Slotting category 2 3 Yes Yes
Mapped rating BB (2.76) BB- (3.15)
Slotting category 3 3 No No
Mapped rating BB- (3.15) B+ (3.49)
Slotting category 3 3 No No
Mapped rating B+ (3.49) B (3.85)
Slotting category 3 4 Yes Yes
Mapped rating B (3.85) B- (4.00)
Slotting category 4 4 No No

As shown in the table, the effect of the reassignment to a lower slotting category on the RWA/EL does not always materialize. The nonmateriality of the denotching process in certain cases has significant implications for the staging process under the IFRS 9 framework, as it does not result in a “significant increase in credit risk”. Without the mapped ratings, every instance of denotching would result in a significant increase in credit risk under the IFRS 9 framework.

The solution presented in this paper is particularly useful for the IFRS 9 staging process, which is based on the internal rating master scale. The IFRS 9 staging process classifies exposures in accordance to their default risk. At this point, under the IFRS 9 framework there are three distinct stages. As mentioned earlier in the paper, an exposure would be reclassified from stage 1 to stage 2 if a significant increase in credit risk is observed. Going forward, the exposure would be reclassified from stage 2 to stage 3 if a credit-impaired status was established. The mapping of the slotting scores to the ratings helps establish specific thresholds for the IFRS 9 staging, as shown in Table 17.

Table 17: Stage 1 to stage 2 reclassification for a maturity of 1.25 years (M=1.25). [This table presents the IFRS 9 denotching process. SC, slotting category.]
  (Corresponding Change in
Denotching slotting score) final SC
BBB BB ([1.00, 1.50) [2.41, 2.76)) 1 2 or 3
BBB- BB- ([1.50, 2.15) [2.76, 3.15)) 2 3
BB+ BB- ([2.15, 2.41) [2.76, 3.15)) 2 3
BB B+ ([2.41, 2.76) [3.15, 3.50)) 2 or 3 3
BB- B ([2.76, 3.15) [3.50, 3.85)) 3 4
B+ B- ([3.15, 3.50) [3.85, 4.00)) 3 4
B B- ([3.50, 3.85) [3.85, 4.00)) 4 4
B- B- ([3.85, 4.00) [3.85, 4.00)) 4 4

An interesting point with reference to the IFRS 9 accounting framework is the LGD trend in the process of minimizing the mapping errors (target RWA and target EL). As shown in Table 9 for the example of the maturity, M, set to 1.25 years, the LGD levels are inconsistent across slotting categories. Under the IFRS 9 accounting framework, LGDs are expected to change consistently across the IRB standardized approach slotting categories. We can assume that the LGDs will either decrease or increase for each slotting category. As shown in Table 9, problems occur when attempting to satisfy a target RWA of 250% for a slotting category of 4. In this case, the LGD increases again to a level of 50% and the monotonic trend of falling LGDs cannot be conserved. However, at this point, a retained PD of 19.81% is more realistic than the PD of 30.7%. Therefore, we challenge the assumption that LGDs should decrease for the lower slotting categories. We note that both the PDs and ELs should increase for real estate specialized lending projects that fall into worse slotting categories. Then, given the fact that the EL is a function of PD and LGD (EL=PD×LGD), it remains counterfactual to expect LGDs to decrease for increasing PDs.

To account for the lack of consistency in LGDs, in this paper we argue against fixing the LGD at 50% for maturities of 1.25 years and 3 years. A visual inspection of Tables 9 and 10 reveals that fixing the LGD at 50% does not minimize the error for the files falling into slotting categories 1 or 3, with the latter suffering from elevated levels of error and significant differences in the PDs, which decreased from 9.2% to 2.29%. Against the background of IFRS 9, fixing the LGDs would constitute a built-in bias to the derived PDs and noncompliance with the new reporting standards. Table 18 shows the differences in PDs stemming from fixing the LGDs at 50%. As shown in the table, the gap is evident for slotting category 3.

Table 18: IFRS 9 gap of fixing LGDs to 50% (α=99.9%). [This table presents the IFRS 9 compliance gaps resulting from fixing the LGDs to 50%. SC, slotting category.]
(a) Maturity = 1.25
SC PD fixed (%) PD optimal (%)
1 00.34 00.34
2 00.65 00.80
3 02.29 09.20
4 19.81 19.81
(b) Maturity = 3
SC PD fixed (%) PD optimal (%)
1 00.34 00.34
2 00.59 01.08
3 01.16 11.21
4 14.54 14.54

Another interesting point with reference to IFRS 9 compliance is the fact that the proposed mapping does not generate ratings that suggest a strong repayment capacity (ie, A+, A, A-) of the obligor. In real estate projects, there is often a good scope for borrowing and access to other cashflows to cover the company’s assets. Further, the BBB and BBB- ratings should not refer to two different slotting categories (SC1 and SC2), as they are assigned to obligors of good repayment capacity, comparable with normal standards in the sector. Although some weaknesses can be identified, these would likely manifest themselves in times of financial distress. Finally, slotting category 2 would include both projects classified as “good” (where the company has borrowing capacity and there are additional cashflows to cover assets) and projects classified as “weak” (where clear weaknesses are identified and the company has no room for maneuver in its repayment capacity). The above points should be taken into consideration by practitioners attempting to map the slotting scores to the corresponding PDs and master scale ratings.

5 Future refinements

Sections 3.4 and 4.1 describe the process of determining the PDs and LGDs using the regulatory RWA levels and EL for combinations of the assumed maturities. In this vein, the maturity M is strictly dependent on the underlying portfolio, and a specific substitution has been made to match it with the portfolio characteristics used in this research. Thus, the choice of 1.25 years and 3 years as representative maturities remains open to estimation error and may change with any changes in the assumptions about the portfolio composition. The validation function is advised to support the choice of M with statistical tests into the stability and sensitivity of the underlying portfolio.

The proposed process of determining the correspondence between the PDs, LGDs and the RWA can be simplified. We use an extended, manual, trial-and-error solution because the aim of this study is to show the problematic side of the slotting approach under IFRS 9. However, if possible, the simultaneous equations can be separated, whereby replacing the LGD with EL/PD reduces the RWA equation to a single unknown (the PD value). This equation is more straightforward to solve numerically using the regulatory formulas and parameters as well as the retained maturity assumptions.

The range of LGDs selected for testing purposes is limited to a ceiling of 50%. With this in mind, future refinements of the proposed approach should consider different LGD boundary points that would match individual circumstances. As it transpires, none of the optimal LGDs in this study is significantly above 50%. Thus, the range adopted remains sufficient. However, we invite explorations of an extended LGD range, where applicable, in order to complement the analysis presented in this paper.

Finally, higher risks are assigned to longer maturities in the RWA regulatory formulas. Therefore, we expect to observe such an ordering of risk in the derived PDs due to the maturity being a periodic influence on normal relationship management. The rank-ordering of PDs was not captured empirically in the proposed process, which delivers some counterintuitive PD ordering compensated by the strong LGD intervention.

Section 4.1 describes the interpolation process of finding the correspondence between the slotting category and the PD. The cubic fit used in doing so allows the PD points to fall exactly on the curve at the integer score points. However, the interpolation process can be subject to nonmonotonic outcomes or nonintuitive oscillations. We do not provide detailed insights into the instabilities of the cubic approach. Therefore, future refinements should analyze the adequacy of the cubic interpolation or use alternatives (eg, a piecewise linear interpolation).

6 Conclusion

In this paper we presented a solution for assigning PD estimates to the slotting scores used as grading estimates under the IRB slotting approach for real estate specialized lending. Toward this aim, we focused on providing a solution for IFRS 9 compliance. As it transpires, the output of a slotting model in credit risk cannot be used for IFRS 9 purposes unless it is converted into PDs and corresponding master scale ratings.

We used a sequential process to derive the correspondence between the slotting scores and the PDs of a particular obligor. In order to align the solution to existing banking practice, the mapping aims to meet the target RWA and the target EL under different sets of exposure maturities. These parameters are based on the regulator-prescribed formulas.

Against the background of the IFRS 9 framework, our solutions produce a more granular rating scale beyond the four slotting categories for credit risk. This increased granularity results in a less punitive denotching mechanism under the IFRS 9 framework. As we have shown, the mapping of individual slotting scores to the ratings taken from a master scale aids banks in satisfying the essential IFRS 9 requirements for the staging process that assesses the increase in credit risk. At this point, we recommend using the midcorporate master rating scale.

We acknowledge that the proposed solution is not free of limitations and suggests that practitioners replicating the mapping exercise should take into consideration several points that may result in IFRS 9 noncompliance. First, since the mapping solution is constructed around the primary risk indicators (LGD and PD), we point to the loss in calibration accuracy when fixing the LGD at a constant value. Second, we recommend a review of the master rating scale. In the example used in this study, the master scale does not allow mapping to strong ratings (eg, A+, A, A-). This affects the discriminatory power of the model and contradicts the assumption that most real estate projects represent cases of obligors with a good scope for borrowing and strong financial performance.

In addition to the core aim of the paper, which translates into the provision of the mapping solution under the IFRS 9 framework, we also explain the methodology of a slotting model, providing an example that can be used by practitioners as a challenger model during their validation exercises. We showed specific modeling choices for the real estate slotting approach aligned to the relevant regulatory framework.

In summary, we discussed topical issues that are being investigated by practitioners. However, the value of our paper is not limited to the practical implications. This paper also sheds light on the under-researched area of modeling credit risk of specialized lending exposures. We recommend further study into modeling solutions for the slotting approach in credit risk. The recommended study would challenge the regulatory-prescribed factors as well as the risk weights assigned to the slotting categories. Note that the EBA is currently reviewing the IRB framework, and a study contributing to the efforts of minimizing the interference of the credit risk slotting models with IFRS 9 is much needed.

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.

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