The risk-weights in the New Basel Capital Accord: Lessons from bond spreads based on a simple structural model

The Basel Committee designed a system of risk weights (“standardised approach”) to measure the riskiness of banks' loan portfolios. We investigate its ability to adequately reflect risk through an analysis of the economic capital implied in corporate bond spreads. This is based on a dataset of issuance spreads, ratings and other relevant bond variables including 7232 eurobonds issued by an internationally-diversified sample during 1991–2003. Three main results emerge: the spread/rating relationship is strongly significant; the estimated spreads per rating class indicate a steeper risk/rating relationship than the one approved by the Basel Committee; no significant difference appears in the spread/rating relation of banks and non-financial firms issuers.     

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.     

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.     

Asset correlations and bank capital adequacy

This paper addresses the estimation of confidence sets for asset correlations used in credit risk portfolio models. Research on the estimation of asset correlations using endogenous probabilities of default estimations has focused on the impact of concentration risk factors, such as firm size and industry. The empirical evidence from Italian small- and medium-size companies show that the assumptions underlying the Basel Committee regulatory capital risk weight function are not substantiated. The regulatory impact is that the capital adequacy is significantly compromised, driving an adverse selection, which favors the worst companies, and transferring the procyclical effects from firms to banks.     

Credit Risk Versus Capital Requirements under Basel II: Are SME Loans and Retail Credit Really Different?

Under Basel II, retail and SME credit (R&SME) receive special treatment because of a supposedly smaller exposure to systemic risk. Most research on this issue has been based on parameterized credit risk models. We present new evidence by applying Carey's (Carey, Mark. “Credit Risk in Private Debt Portfolios.” Journal of Finance 53, no. 4 (1998), 1363–1387.) nonparametric Monte-Carlo resampling method to two banks' complete loan portfolios. By exploiting that a sub-sample of all borrowers has been assigned an internal rating by both banks, we can compare the credit loss distributions for the three credit types, and compute both economic and regulatory capital under Basel II. We also test if our conclusions are sensitive to the definitions of R&SME credit. Our findings show that R&SME portfolios are usually riskier than corporate credit. Special treatment under Basel II is thus not justified. JEL classification: C14, C15, G21, G28, G33.     

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.     

Stress testing credit risk: The Great Depression scenario

By employing Moody’s corporate default and rating transition data spanning the last 90 years we explore how much capital banks should hold against their corporate loan portfolios to withstand historical stress scenarios. Specifically, we will focus on the worst case scenario over the observation period, the Great Depression. We find that migration risk and the length of the investment horizon are critical factors when determining bank capital needs in a crisis. We show that capital may need to rise more than three times when the horizon is increased from 1 year, as required by current and future regulation, to 3 years. Increases are still important but of a lower magnitude when migration risk is introduced in the analysis. Further, we find that the new bank capital requirements under the so-called Basel 3 agreement would enable banks to absorb Great Depression-style losses. But, such losses would dent regulatory capital considerably and far beyond the capital buffers that have been proposed to ensure that banks survive crisis periods without government support.     

Financial stability and Basel II

The Basel II Advanced Internal Ratings (AIRB) approach is compared to capital requirements set using an equilibrium structural credit risk model. Analysis shows the AIRB approach undercapitalizes credit risk relative to regulatory targets and allows wide variation in capital requirements for a given exposure owing to ambiguity in the definitions of loss given default and exposure at default. In contrast, the Foundation Internal Ratings Based (FIRB) approach may over-capitalize credit risk relative to supervisory objectives. It is unclear how Basel II will buttress financial sector stability as it specifies the weakest regulatory capital standard for large complex AIRB banks.      

《新资本协议》对商业银行信贷运行的影响——兼论其宏观经济效应

《新资本协议》的出台和实施是银行监管历史上一个具有里程碑意义的事件。本文认为,《新资本协议》特别是内部评级法极大地提高了资本监管的风险敏感度,将对商业银行的信贷增长方式、信贷结构调整和贷款损失准备计提、以及宏观经济运行产生一定的影响。按照目前我国商业银行资本充足水平和资产质量,无论是实施标准法还是内部评级法都将强化信贷扩张的资本约束效应。我国应慎重选择《新资本协议》的实施时机,避免由此对信贷供给和宏观经济运行造成的负面冲击。     

创新信用衍生工具 提升风险管理能力——巴塞尔协议Ⅲ背景下的CRM

最新公布的巴塞尔协议Ⅲ,要求银行业充分吸取金融危机教训,切实加强信用风险管理。中国银行间市场推出的信用风险缓释工具,具有多项创新价值,发挥了本土市场成功经验。从微观角度,该工具有助于提高信用风险动态管理能力、丰富资本管理手段、支持逆周期管理和灵活平衡集中度;从宏观角度,该工具有助于打造渐进式风险管理机制、强化资本约束并带动市场基础建设。为进一步推进中国信用衍生产品市场发展,建议发挥商业银行的主导作用和非银行机构的辅助作用,完善交易机制、定价机制和会计处理,创新清算机制,并纳入银行自身风险管理流程。