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.     

The New Basel Capital Accord: Making it Effective with Stronger Market Discipline

In January 2001 the Basel Committee on Banking Supervision proposed a new capital adequacy framework to respond to deficiencies in the 1988 Capital Accord on credit risk. The main elements or 'pillars' of the proposal are capital requirements based on the internal risk-ratings of individual banks, expanded and active supervision, and information disclosure requirements to enhance market discipline. We discuss the incentive effects of the proposed regulation. In particular, we argue that it provides incentives for banks to develop new ways to evade the intended consequences of the proposed regulation. Supervision alone cannot prevent banks from 'gaming and manipulation' of risk-weights based on internal ratings. Furthermore, the proposed third pillar to enhance market discipline of banks' risk-taking is too weak to achieve its objective. Market discipline can be strengthened by a requirement that banks issue subordinated debt. We propose a first phase for introducing a requirement for large banks to issue subordinated debt as part of the capital requirement.     

巴塞尔委员会逆周期资本框架在我国银行业的实证分析

2010年12月16日,巴塞尔委员会公布了《第三版巴塞尔协议》和《各国监管当局实施逆周期资本缓冲指引》,要求各国监管当局参照制定逆周期资本缓冲政策框架,并视需要要求银行计提逆周期资本缓冲。本文采用我国银行业的数据,对该资本缓冲政策框架进行了实证分析,并就我国实施逆周期资本缓冲政策提出了政策建议。     

Bank regulation and international financial stability: A case against the 2006 Basel framework for controlling tail risk in trading books

In attempting to promote international financial stability, the Basel Committee on Banking Supervision (2006) provided a framework that sought to control the amount of tail risk that large banks around the world would take in their trading books relative to their corresponding minimum capital requirements. However, many of these banks suffered significant trading losses during the recent financial crisis. Our paper examines whether the Basel framework allowed banks to take substantive tail risk in their trading books without a capital requirement penalty. We find that it allowed banks to do so and that its minimum capital requirements can be notably procyclical. Hence, focusing on the way the Basel framework sought to control the amount of tail risk in trading books relative to their corresponding minimum capital requirements, our paper supports the view that it was not properly designed to promote financial stability. We also discuss alternative regulatory frameworks that would potentially be more effective than the Basel framework in preventing banks from taking substantive tail risk in their trading books without a capital requirement penalty.     

The cyclical effects of the Basel II capital requirements

Capital requirements play a key role in the supervision and regulation of banks. The Basel Committee on Banking Supervision is in the process of changing the current framework by introducing risk sensitive capital charges. Some fear that this will unduly increase the volatility of regulatory capital. Furthermore, by limiting the banks’ ability to lend, capital requirements may exacerbate an economic downturn. The paper examines the problem of capital-induced lending cycles and their pro-cyclical effect on the macroeconomy in greater detail. It finds that the capital buffer that banks hold on top of the required minimum capital plays a crucial role in mitigating the impact of the volatility of capital requirements.     

Does the Basle Capital Accord reduce bank fragility? An assessment of the value-at-risk approach

We examine the economic implications arising from a bank using a VaR-constrained mean-variance model for the selection of its trading portfolio as a consequence of the Basle Capital Accord. Surprisingly, we show that when a VaR constraint is imposed, it is plausible that certain banks will end up selecting ‘riskier’ portfolios than they would have chosen in the absence of the constraint. Accordingly, regulators such as the Basle Committee on Banking Supervision should be aware that allowing a bank to use VaR to determine its minimum regulatory capital may increase its fragility. Alternatives to VaR-based bank capital regulation that mitigate or even preclude its perverse implications are presented.     

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.     

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.     

Does prudential regulation contribute to effective measurement and management of interest rate risk? Evidence from Italian banks

This paper contributes to prior literature and to the current debate concerning recent revisions of the regulatory approach to measuring bank exposure to interest rate risk in the banking book by focusing on assessment of the appropriate amount of capital banks should set aside against this specific risk. We first discuss how banks might develop internal measurement systems to model changes in interest rates and measure their exposure to interest rate risk that are more refined and effective than are regulatory methodologies. We then develop a backtesting framework to test the consistency of methodology results with actual bank risk exposure. Using a representative sample of Italian banks between 2006 and 2013, our empirical analysis supports the need to improve the standardized shock currently enforced by the Basel Committee on Banking Supervision. It also provides useful insights for properly measuring the amount of capital to cover interest rate risk that is sufficient to ensure both financial system functioning and banking stability.     

Ratings based capital adequacy for securitizations

This paper develops a framework to measure the exposure to systematic risk for pools of asset securitizations and measures empirically whether current ratings-based rules for regulatory capital of securitizations under Basel II and Basel III reflect this exposure. The analysis is based on a comprehensive US dataset on asset securitizations for the time period between 2000 and 2008. We find that the shortfall of regulatory capital during the Global Financial Crisis is strongly related to ratings. In particular, we empirically show that insufficient capital is allocated to tranches with the highest rating. These tranches account for the greatest part of the total issuance volumes. Furthermore, this paper is the first to calibrate risk weights which account for systematic risk and provide sufficient capital buffers to cover the exposure during similar economic downturns. These policy-relevant findings suggest a re-calibration of RBA risk weights and may contribute to the current efforts by the Basel Committee on Banking Supervision and others to re-establish sustainable securitization markets and to improve the stability of the financial system.     

The Evolving Complexity of Capital Regulation

This article traces the growing complexity of capital regulation with emphasis on decisions of the Basel Committee on Banking Supervision and bank regulators in the US. The pattern is one of increasingly complex regulations as each round of reform attempts to correct perceived weaknesses in the earlier regime. The outcome is a regulatory framework that is remarkably opaque, costly to monitor and enforce, and imposes heavy compliance costs on the regulatees, which are inevitably passed on in part to users of financial services. After a discussion of the most recent round of reforms, the article presents a table organized by five different regulatory capital numerators and five different denominators that define thirtynine different regulatory capital requirements, which Globally Significant US banks must meet. This way of organizing the various capital requirements shows how the number of capital ratios could be reduced by 75% with no loss of rigor. The conclusion speculates about why regulatory simplification seems so much more difficult to accomplish in the US than in other countries with much longer regulatory traditions.     

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.     

Implementation of Basel II

In this article Jaime Caruana, Governor of the Bank of Spain and Chairman of the Basel Committee on Banking Supervision, first discusses the current status of the Basel II Accord. Next, he offers his perspective on macroeconomic issues related to the capital framework, focusing especially on pro‐cyclicality. Finally, he discusses three important Basel II implementation issues, namely calibration, validation, and cross‐border supervision.     

《银行资本充足率监管征求意见稿》的影响研究

2011年5月,银监会下发了融合《巴塞尔协议II》及《巴塞尔协议III》内关于资本计量、管理等内容的《银行资本充足率监管征求意见稿》,这标志着金融危机后我国的新监管标准即将落地。该监管新规将使国有五大行资本充足率下降。五大行可以从补充资本、降低加权风险资产、增强资本管理能力等方面应对监管新规。     

压力测试及其在中美两国中的应用

在全球金融危机之中,传统的风险评估和预警机制没有发挥预期作用,压力测试作为一个重要评估工具,逐渐被各界重视。巴塞尔银行监管委员会于2009年5月发布了《压力测试实践和监管稳健原则》,针对压力测试在各个金融机构中的运用有了具体的指导思想,而同年美国为应对次贷危机在19家银行间开展的压力测试也是一次具有较大影响力的尝试。另一方面,在中国房地产市场面临调整的情况下,作为一种新型的风险检验方法,2010年中国银监会针对银行房地产信贷开展的大规模压力测试,其结果则有待实践检验。     

Quantifying the Interest Rate Risk of Banks: Assumptions Do Matter

This paper analyses the robustness of the standardised framework proposed by the Basel Committee on Banking Supervision (2004b) to quantify the interest rate risk of banks. We generalise this framework and study the change in the estimated level of interest rate risk if the strict assumptions of the standardised framework are violated. Using data on the German universal banking system, we find that estimates of the interest rate risk are very sensitive to the framework's assumptions. We conclude that the results obtained using the standardised framework in its current specification should be treated with caution when used for supervisory and risk management purposes.     

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.     

Timeliness of Spread Implied Ratings

Rating agencies are known to be prudent in their approach to rating revisions, which results in delayed rating adjustments. For a large set of eurobonds we derive credit spread implied ratings and compare them with agency ratings. Our results indicate that spread implied ratings often anticipate the future movement of agency ratings and hence can help track credit risk in a more timely manner. This finding has important implications for risk managers in banks who, under the new Basel 2 regulations, have to rely more on credit ratings for capital allocation purposes, and for portfolio managers who face rating‐related investment restrictions.     

Capital shocks, bank asset allocation, and the revised Basel Accord

In contrast to the 1988 Basel Accord (Basel I), the revised risk-based capital standards (Basel II) propose regulatory capital requirements based on credit ratings. This paper develops a theoretical model to analyze how banks will adjust their low and high credit risk commercial loans under the proposed newer standard. Capital-constrained banks respond to an adverse capital shock by reducing high credit risk loans, while under certain circumstances, low credit risk loans may actually increase. When compared to Basel I, it is shown that high-risk loans are reduced more under Basel II, but whether a bank reduces total lending more under Basel I or under the revised standards depends on a complex interaction of factors.     

Loss coverage and stress testing mortgage portfolios: A non-parametric approach

This paper outlines the development of a practical approach to simulating a credit loss distribution function and to implementing a stress test exercise focusing on the entire Spanish mortgage portfolio. Specifically, we determine, via regression model, the main factors that explain why households fail to meet their mortgage payment commitments. This allows us to assign individual borrowers’ PDs and to estimate a rating system for the mortgage portfolio. Then, we simulate the empirical distribution function of mortgage loss rates using a Monte-Carlo resampling method, and compare the loss rates from this function with those provided by the Basel II IRB formulas. Finally, we assess, by running a stress exercise, the ability of banks to withstand certain adverse situations. The main result from this exercise is that, in general terms, Basel II IRB regulatory loss coverage offers fairly adequate protection for banks.