The manipulation of basel risk-weights

In this paper, we examine the relationship between banks’ approval for the internal ratings-based (IRB) approaches of Basel II and the ratio of risk-weighted assets to total assets. Analysing a panel of 115 banks from 21 OECD countries that were eventually approved for applying the IRB to their credit portfolio, we find that risk-weight density becomes lower once regulatory approval is granted. The effect persists when we control for asset structure, and we provide evidence showing that this phenomenon cannot be explained by modelling choices, or improved risk-measurement alone. Consistent with theories of risk-weight manipulation, we find the decline in risk-weights to be particularly pronounced among weakly capitalised banks, where the legal framework for supervision is weak, and in countries where supervisors are overseeing many IRB banks. We conclude that part of the decline in reported riskiness under the IRB results from banks’ strategic risk-modelling.     

An Assessment of Basel II Procyclicality in Mortgage Portfolios

In this paper we develop a probability of default (PD) model for mortgage loans, taking advantage of the Spanish Credit Register, a comprehensive database on loan characteristics and credit quality. From that model, we calculate different types of PDs: point in time, PIT, through the cycle, TTC, average across the cycle and acyclical. Then, we compare capital requirements coming from the different Basel II approaches. We show that minimum regulatory capital under Basel II can be very sensitive to the risk measurement methodology employed. Thus, the procyclicality of regulatory capital requirements under Basel II is an open question, depending on the way internal rating systems are implemented and their output is utilised. We focus on the mortgage portfolio since it is one of the most under researched areas regarding the impact of Basel II and because it is one of the most important of banks’ portfolios.     

Loan pricing under Basel capital requirements

We analyze the loan pricing implications of the reform of bank capital regulation known as Basel II. We consider a perfectly competitive market for business loans where, as in the model underlying the internal ratings based (IRB) approach of Basel II, a single risk factor explains the correlation in defaults across firms. Our loan pricing equation implies that low risk firms will achieve reductions in their loan rates by borrowing from banks adopting the IRB approach, while high risk firms will avoid increases in their loan rates by borrowing from banks that adopt the less risk-sensitive standardized approach of Basel II. We also show that only a very high social cost of bank failure might justify the proposed IRB capital charges, partly because the net interest income from performing loans is not counted as a buffer against credit losses. A net interest income correction for IRB capital requirements is proposed.     

内部评级法思想及其在商业银行风险管理中的应用

为提升国内银行的风险管理能力,银监会不断推进实施新资本协议.内部评级法作为新资本协议的核心内容,其基本思想对于商业银行提高风险管理能力具有重要指导作用.本文从内部评级法的基本思想入手,结合内部评级法在国内银行风险管理中的应用情况,提出应用内部评级法加强国内银行风险管理的政策建议.     

个人住房抵押贷款违约风险跃迁概率研究

巴塞尔新资本协议提出针对个人住房抵押贷款可采用内部评级高级法评估其风险,在满足某些最低条件和披露要求的前提下,商业银行可根据自己对个人住房抵押贷款违约概率、违约损失率、违约风险暴露和期限等要素的估计值确定相应的资本要求。本文提出将风险跃迁概率引入到对个人住房抵押贷款提前还款-违约概率的定量估计中。借助逻辑斯特模型,本文将这一概念实际运用到对个人住房抵押贷款微观数据的分析当中,得到的实证研究结论包括借款人历史还款状态可以作为表征其未来还款状态的重要指标,贷龄与借款人还款状态的跃迁概率显著相关等。     

Bank size and risk-taking under Basel II

We analyze the relationship between bank size and risk-taking under the Basel II Capital Accord. Using a model with imperfect competition and moral hazard, we show that the introduction of an internal ratings based (IRB) approach improves upon flat capital requirements if the approach is applied uniformly across banks and if the costs of implementation are not too high. However, the banks’ right to choose between the standardized and the IRB approaches under Basel II gives larger banks a competitive advantage and, due to fiercer competition, pushes smaller banks to take higher risks. This may even lead to higher aggregate risk-taking.     

Modelling the economic value of credit rating systems

In this paper we develop a model of the economic value of credit rating systems. Increasing international competition and changes in the regulatory framework driven by the Basel Committee on Banking Supervision (Basel II) called forth incentives for banks to improve their credit rating systems. An improvement of the statistical power of a rating system decreases the potential effects of adverse selection, and, combined with meeting several qualitative standards, decreases the amount of regulatory capital requirements. As a consequence, many banks have to make investment decisions where they have to consider the costs and the potential benefits of improving their rating systems. In our model the quality of a rating system depends on several parameters such as the accuracy of forecasting individual default probabilities and the rating class structure. We measure effects of adverse selection in a competitive one-period framework by parameterizing customer elasticity. Capital requirements are obtained by applying the current framework released by the Basel Committee on Banking Supervision. Results of a numerical analysis indicate that improving a rating system with low accuracy to medium accuracy can increase the annual rate of return on a portfolio by 30–40 bp. This effect is even stronger for banks operating in markets with high customer elasticity and high loss rates. Compared to the estimated implementation costs banks could have a strong incentive to invest in their rating systems. The potential of reduced capital requirements on the portfolio return is rather weak compared to the effect of adverse selection.     

The Basel Committee proposals for a new capital accord: implications for Italian banks

Following a few general considerations on the recently proposed revision of the Basel Agreement on capital adequacy, this paper focuses on the first pillar of the Basel Committee proposals, the handling of capital requirements for credit risk in the banking book. The Basel Committee envisages an approach alternatively based on external ratings or on internal rating systems for the determination of the minimum capital requirement related to bank loan portfolios. This approach supports a system of capital requirements that is more sensitive to credit risk. On the basis of specific assumptions, these requirements provide a measure of the value at risk (VaR) produced by models used by major international banks. We first address the impact of the standardised and (internal ratings-based) IRB foundation approach using general data on Italian banks loans' portfolios default rates. We then simulate the impact of the proposed new rules on the corporate loan portfolios of Italian banks, using the unique data set of mortality rates recently published by the Bank of Italy. Three main conclusions emerge from the analysis: (i) the standardised approach implicitly penalizes Italian banks in their interbank funding as their rating is generally below AA/Aa, (ii) the average default rate experienced by Italian banks is higher than the one implied in the benchmark risk weight (BRW) proposed by the Basel Committee for the IRB foundation approach, thereby potentially leading to an increase in the regulatory risk weights, and (iii) the risk-weight is based on an average asset correlation that is significantly higher than the one historically recorded within the Italian banks' corporate borrowers. These findings support the need for a significant revision of the basic inputs and assumptions of the Basel proposals. Finally, in relation to the conditions that allow the capital market to effectively discipline banks, we comment on the proposals advanced in relation to the third pillar of the new capital adequacy scheme.     

Approximate value-at-risk calculation for heterogeneous loan portfolios: Possible enhancements of the Basel II methodology

This paper presents three possible methods by which the credit value at risk estimates coming from the Basel II IRB approach can be significantly improved upon. The feasibility of the suggested approaches is substantiated by applying it to an exemplary model portfolio.     

IRB法下公司敞口组合的风险驱动因子计量研究

巴塞尔银行监管委员会针对防范信贷组合信用风险所需要的资本制定的内部评级法,通过风险驱动因子的变化来反映组合回报的变化,并根据风险权重函数,通过风险加权资产转化为与每一项信用风险敞口更准确匹配的资本要求.本文对违约概率、违约损失率、违约敞口、期限因素以及违约相关性等信贷组合信用风险的风险驱动因子的度量进行了综合研究.     

Risk-based capital requirements for mortgage loans

We contribute to the debate over the reform of the Basel Accord by developing risk-based capital requirements for mortgage loans held in portfolio by financial intermediaries. Our approach employs simulation of both economic variables that affect default incidence and conditional loss probability distributions. Results indicate that appropriate capital charges for credit risk vary substantially with loan characteristics and portfolio geographic diversification. Hence, rules that offer little risk differentiation, including the current Basel I regime and “standardized” approach proposed in Basel II result in significant divergence between regulatory and economic capital. These results highlight the incentive problems inherent in simplified methods of capital regulation.     

A practical approach to validating a PD model

The capital adequacy framework Basel II aims to promote the adoption of stronger risk management practices by the banking industry. The implementation makes validation of credit risk models more important. Lenders therefore need a validation methodology to convince their supervisors that their credit scoring models are performing well. In this paper we take up the challenge to propose and implement a simple validation methodology that can be used by banks to validate their credit risk modelling exercise. We will contextualise the proposed methodology by applying it to a default model of mortgage loans of a commercial bank in the Netherlands.     

Economic capital for nonperforming loans

A portfolio of nonperforming loans requires economic capital. We present two models for forecasting the portfolio loss and its probability distribution. In the first model, the loss for each nonperforming loan entails a change in provision over the risk horizon. The risk determinants are the single-name concentration, measured by the Herfindahl–Hirschmann index, as well as a systematic factor and the idiosyncratic risk. Our second model allows for interportfolio diversification with a portfolio of performing loans because banks typically own both performing and nonperforming loans. In this model, the nonperforming loan is identified with its systematic risk. Both models allow for closed-form expressions of economic capital and for the capital charge of the single loan. We calibrate the macroeconomic model parameters statistically with a loss panel; the microeconomic parameters depend on the portfolio. The portfolio risk for nonperforming loans mainly depends on the volatility of the systematic economic factor. The dependence becomes more pronounced when interportfolio diversification is taken into account. The magnitude of interportfolio diversification is also marked. Finally, we calculate regulatory capital charges according to Basel II for past-due loans. The regulatory charges are on average smaller than our economic charges and, additionally, take the volatility of economic activity into account only implicitly.     

资本计量方法改革、商业银行风险偏好与信贷配置

为提高银行业风险管理水平与信贷配置效率,监管部门于2014年开展了资本管理高级方法的试点工作。本文基于上市银行2010至2016年的微观数据,与银监会公布的行业信贷风险进行匹配,采用双重差分和三重差分法,实证分析前述改革如何影响试点银行的风险偏好和信贷调配。研究发现,在资本管理高级方法实施后:(1)试点银行显著降低了风险加权资产的规模;(2)试点银行风险偏好的变化存在非线性的特征,在调减高风险行业贷款的同时,并未显著增加最安全行业的贷款,而是增加了风险略高行业的贷款,体现出试点银行对风险与收益的权衡;(3)进一步将行业划分为“虚”与“实”,研究发现试点银行减少了房地产业(“虚”)、制造业(“实”)和建筑业(“实”)贷款,显著增加了金融业(“虚”)贷款。本文研究不仅丰富了资本监管方面的文献,也对金融支持供给侧结构性改革具有启示意义。     

Effects of the New Basel Capital Accord on Bank Capital Requirements for SMEs

Using data from three countries (US, Italy and Australia) and surveying related studies from several other countries in Europe, we investigate the effects of the New Basel Capital Accord on bank capital requirements for small and medium sized enterprises (SMEs). We find that, for all the countries, banks will have significant benefits, in terms of lower capital requirements, when considering small and medium sized firms as retail customers. But they will be obliged to use the Advanced IRB approach and to manage them on a pooled basis. For SMEs as corporate, however, capital requirements will be slightly greater than under the existing Basel I Capital Accord. We believe that most eligible banks will use a blended approach (considering some SMEs as retail and some as corporate). Through a breakeven analysis, we find that for all of our countries, banking organizations will be obliged to classify as retail at least 20% of their SME portfolio in order to maintain the current capital requirement (8%). JEL classification: G21, G28     

Capital requirements and mortgage pricing: Evidence from Basel II

As a result of the Basel II reforms, capital requirements on UK mortgages fell substantially in coincidence with the financial crisis. We exploit a novel, loan-level dataset on within-lender variation in risk-weighted capital requirements and a triple-difference identification strategy to estimate the pass through of capital requirements to mortgage rates. We find that a 1pp lower risk-weighted capital requirement leads to a reduction in rates by 10–16bp on average, with stronger effects for less-capitalized lenders. The competitive advantage induced by multi-tier regulation also affects the composition of banks mortgage portfolios, with larger lenders specializing in lower risk loans. Finally, our results support the use of countercyclical capital requirements to sustain lending in a crisis.     

Competitive effects of Basel II on US bank credit card lending

We analyze the potential competitive effects of the proposed Basel II capital regulations on US bank credit card lending. We find that bank issuers operating under Basel II will face higher regulatory capital minimums than Basel I banks, with differences due to the way the two regulations treat reserves and gain-on-sale of securitized assets. During periods of normal economic conditions, this is not likely to have a competitive effect; however, during periods of substantial stress in credit card portfolios, Basel II banks could face a significant competitive disadvantage relative to Basel I banks and nonbank issuers.     

The Cross‐Market Spillover of Economic Shocks through Multimarket Banks

This study investigates the mortgage lending of banks operating in multiple U.S. metropolitan areas during the housing market collapse of 2007–09. We show that multimarket banks reduced local portfolio lending in response to high overall mortgage delinquencies in their other markets, consistent with the view that local economic shocks can be transmitted to other regions through banks’ internal capital markets. This spillover was greatest when the bank lacked a branch presence and when the market was highly peripheral to the bank in terms of its total mortgage lending. These effects were not fully offset by securitization or other portfolio lenders.     

Charter Value, Risk-Taking Incentives, and Emerging Competition for Fannie Mae and Freddie Mac

This paper examines two forces that may soon increase competition in the U.S. secondary conforming mortgage market: (1) the Federal Home Loan Bank mortgage purchase programs, and (2) the adoption of revised risk-based capital requirements for large U.S. banks (Basel II). We argue that this competition is likely to reduce the growth and relative importance of Fannie Mae and Freddie Mac and hence reduce their charter values and effective capital. Such developments could, in turn, lead to more risky behaviors by these two companies. This last consequence warrants greater supervisory awareness and legal authorities.     

The use of credit scoring in the mortgage industry

In times of increased focus on risk management, acquiring or growing comparatively low risk mortgage portfolios has become an attractive value proposition. Banks that pursue an aggressive growth strategy in this sector, do, however, require risk control mechanisms that enable them to make a clear judgment on how great a growth appetite they can afford to have in order to still grow profitably. Moreover, under Basel II, the proper quantification of mortgage portfolio risk tends to help the release of own capital, because the mortgage portfolio is one of those portfolios where the relative benefits of internal ratings-based approaches compared with the standardised approach are greatest. Credit scoring models in general, and credit scorecards in particular, are suitable methods for quantifying the risk of an individual mortgage applicant or mortgage customer. In addition to score card development, this paper reviews alternative scoring model types that could be used for mortgage scoring. It presents reasons why it is beneficial to build such models in-house, before focusing on the steps necessary for building a mortgage scorecard. Finally, it discusses the important topics of creating segments, deploying models and eventually monitoring models.