Capital adequacy rules, catastrophic firm failure, and systemic risk

This paper studies capital adequacy rules based on Value-at-Risk (VaR), leverage ratios, and stress testing. VaR is the basis of Basel II, and all three approaches are proposed in Basel III. This paper makes three contributions to the literature. First, we prove that these three rules provide an incentive to increase the probability of catastrophic financial institution failure. Collectively, these rules provide an incentive to increase (not decrease) systemic risk. Second, we argue that an unintended consequence of the Basel II VaR capital adequacy rules was the 2007 credit crisis. Third, we argue that to reduce systemic risk, a new capital adequacy rule is needed. One that is based on a risk measure related to the conditional expected loss given insolvency.     

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.     

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.     

Loan pricing under Basel II in an imperfectly competitive banking market

The new Basel II Accord (2006), established new and revised capital requirements for banks. In this paper we analyze and estimate the possible effects of the new rules on the pricing of bank loans. We relate to the two approaches for capital requirements (internal and standardized) and distinguish between retail and corporate customers. Our loan-equation is based on a model of a banking firm facing uncertainty operating in an imperfectly competitive loan market. We use Israeli economic data and data of a leading Israeli bank. The main results indicate that high quality corporate and retail customers will enjoy a reduction in loan interest rates in (big) banks which, most probably, will adopt the IRB approach. On the other hand high risk customers will benefit by shifting to (small) banks that adopt the standardized approach.     

On the Role of Regulatory Banking Capital

In this paper the authors study the role of regulatory banking capital and analyze the incentive effects of the Basel II Accord. They argue that Basel II may become a source of systemic risk due to endogenous risk and the risk sensitivity of the capital requirements. In this context they note that financial instability may enter via the asset side of the banks' balance sheets when banks are forced to sell assets in order to maintain the capital buffer prescribed by Basel II.     

A leverage ratio rule for capital adequacy

This paper studies the economic foundations for maximum leverage ratio capital adequacy rules. The paper makes three contributions to the literature. First, we show how to determine the maximum leverage ratio such that the probability of insolvency is less than some predetermined quantity. Two, we show that a leverage ratio rule controls for the same risks as does a Value-at-Risk (VaR) capital adequacy rule. Third, we argue that leverage ratio rules are better than VaR rules because they are more intuitive and easier to compare across firms.     

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.      

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.     

Capital requirements under the credit risk-based framework

This work aims to study the hypothesis of lower capitalization of banks under the risk-based rules introduced in Basel II. In this sense, an assessment of the impact of these rules on the capital requirements for non-financial firms’ credit risk is performed. A comparison with Basel I is presented and intervals of variation for the risk drivers such that capital requirements exceed the ones under Basel I are established. Data for a European country supports the hypothesis of a smaller capitalization of banks under the risk-based framework, as far as credit risk in concerned.     

Market crises and Basel capital requirements: Could Basel III have been different? Evidence from Portugal,Ireland, Greece and Spain (PIGS)

Basel III represents a crucial step in strengthening the capital rules underlying banking operations, aimed at reducing the probability and severity of a systemic crisis. Alongside two supplementary capital buffers, the Basel Committee of Banking Supervision imposed severe pressure on the Value-at-Risk based Internal Models Approach in order to increase. This is to increase the capital base by adding the stressed Value-at-Risk component in an effort to reduce reliance on internal models while keeping the Standardized Approach avenue open. However, even though those measures might appear theoretically correct, evidence gathered for long and short exposures in Portugal, Italy, Greece and Spain highlights several defects in Basel III. We emphasize that leptokurtic models, primarily those derived from Extreme Value Theory, should be enforced in the regulations given their superior performance in market crises, and that Basel II could have shielded against 2008 mayhem provided that heavy-tailed techniques had been employed.     

次贷危机对新资本协议实施的影响

本文以风险管理为切入点,讨论次贷危机与新资本协议之间的关系,试图回答业界对新资本协议制度合理性的某些质疑。与1988年资本协议相比,新资本协议建立了更具灵活性、适应性和前瞻性的资本监管制度,赋予资本充足率更加丰富的风险管理内涵,为商业银行改进风险管理提供了正向激励;次贷危机不仅未否认新资本协议的合理性,反而进一步凸现了全面实施新资本协议的重要性;新资本协议应顺应金融创新的趋势,吸取次贷危机的教训,做出适应性调整;虽然实施新资本协议不可能阻止金融危机再度发生,但可以提升银行体系应对外部冲击的能力,至少可以缓解未来金融危机的破坏力,从而提高社会福利。     

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.     

Capital Allocation for Portfolio Credit Risk

Capital allocation rules are derived that maximize leverage while maintaining a target solvency rate for credit portfolios where risk is driven by a single common factor and idiosyncratic risk is fully diversified. Equilibrium conditions ensure that capital allocations depend on interest earnings as well as credits’ probability of default, endogenous loss given default, and asset correlation. Capitalization rates exceed those estimated using Gaussian credit loss models. Results demonstrate that credit risk is undercapitalized by the Basel II AIRB approach in part because of ambiguities regarding the definition of loss given default. An alternative proposed capital rule removes this bias.     

A real options approach for evaluating the implementation of a risk-sensitive capital rule in banks

I evaluate a bank's incentives to implement a risk-sensitive regulatory capital rule. The decision making is analyzed within a real options framework where optimal policies are derived in terms of threshold levels of credit risk. I provide a numerical example for the implementation of internal ratings based models for credit risk (the IRB approach) under the new Basel Accord (Basel II).     

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.     

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.     

Implicit recourse and credit card securitizations: What do fraud losses reveal?

In this paper, we develop and test a model of implicit recourse in asset-backed securitizations. Fraud losses on securitized assets are generally incurred by the bank and do not affect the performance of securitization trusts, while credit losses do affect the trust’s performance and are potentially borne by the owner of the securitized assets. Thus, the classification of losses as either fraud or credit losses provides a potential avenue of implicit recourse to manipulate the performance of securitization trusts. Using annual data from 2001 to 2006, we find that the performance of the credit card securitization portfolio is negatively related to fraud losses reported by the bank. We examine these results in light of the proposed Basel II capital rules and argue that a bank’s incentive to provide implicit recourse will increase under the anticipated regime.     

What drives the liquidity of sovereign bonds when markets are under stress? An assessment of the new Basel 3 rules on bank liquid assets

The new rules on bank liquidity set by the Basel Committee require banks to hold high-quality liquid assets (HQLAs) against future cash outflows in periods of market stress. Domestic government bonds are considered to be HQLAs. To assess the appropriateness of this rule, we investigate the liquidity of European government bonds in ordinary times and in periods of market turmoil. We find that the effect of adverse market conditions on liquidity strongly depends on individual bond’s characteristics. Our evidence argues for rules on HQLAs that should constrain the eligibility of government bonds depending on their characteristics (primarily, duration and rating).     

Private equity and regulatory capital

Regulatory capital requirements for European banks have been put forward in the Basel II Capital Framework and subsequently in the capital requirements directive (CRD) of the EU. We provide a detailed discussion of the capital requirements for private equity investments under different approaches. For the internal model approach we present a structural model that we calibrate to a proprietary dataset. We modify the standard Merton structural model to make it applicable in practice and to capture stylized facts of private equity investments. We also implement the early default feature with a fast simulation algorithm. Our results support capital requirements lower than in Basel II, but not as low as in CRD, thereby giving adverse incentives to banks for using advanced risk models. A sensitivity analysis shows that this finding is robust to parameter uncertainty and stress scenarios.     

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.