Valuation of synthetic CDOs

In this paper, we consider the valuation of a synthetic collateralized debt obligation (CDO), a pool of underlying credit risky securities, “partitioned” into several tranches, each of which absorbs losses in accordance with its size and seniority. We derive a closed-form solution for credit spreads of the tranches of homogeneous pools and find an approximation for the credit spreads of inhomogeneous pools. The method leads to an accurate estimation of the credit spreads of synthetic CDOs and can be used in risk management applications.     

A comparative analysis of ex ante credit spreads: Structured finance versus straight debt finance

This paper examines the pricing of structured finance (SF) – asset-backed securities (ABS), mortgage-backed securities (MBS), and collateralized debt obligations (CDO) – and straight debt finance transactions. Using a cross-section of 24,525 European bonds issued by financial and nonfinancial firms in the 2000–2016 period, we show that although ratings are the most important pricing determinant for SF and corporate bonds (CB) at issuance, investors rely on other contractual, macroeconomic, and firms’ characteristics beyond these ratings. We find that CDO tranches have, on average, higher credit spreads than similarly rated CB, while investors are not compensated for facing higher systematic risk components in relation to investment-grade ABS and MBS. Our results also support the hypothesis of SF transactions as mechanisms of reducing funding costs: SF transactions’ weighted average spread is lower than that of comparable CB and originating firms’ creditworthiness does not deteriorate when compared to a sample of matched firms.     

On the Relative Pricing of Long‐Maturity Index Options and Collateralized Debt Obligations

We investigate a structural model of market and firm‐level dynamics in order to jointly price long‐dated S&P 500 index options and CDO tranches of corporate debt. We identify market dynamics from index option prices and idiosyncratic dynamics from the term structure of credit spreads. We find that all tranches can be well priced out‐of‐sample before the crisis. During the crisis, however, our model can capture senior tranche prices only if we allow for the possibility of a catastrophic jump. Thus, senior tranches are nonredundant assets that provide a unique window into the pricing of catastrophic risk.     

债务抵押凭证（CDO）的风险与信用评级研究

债务抵押凭证（CDO）是金融市场重要的风险转移工具，具有信用级别高、收益水平高的特征，其市场规模扩展迅速。但这种金融创新产品因较复杂的基础资产和分层结构，产生出异于传统公司债券的风险特征。很多投资者没有真正了解其潜在风险，且信用评级质量不佳，致使CDO投资者在次贷危机中遭受严重损失甚至破产。因此有必要深入了解CDO所具有的风险特征和CDO产品信用评级的一般方法，纠正现有评级方法的不足，分析其对次贷危机的影响。     

Valuation of collateralized debt obligations with hierarchical Archimedean copulae

Modelling portfolio credit risk is one of the crucial challenges faced by financial services industry in the last few years. We propose the valuation model of collateralized debt obligations (CDO) based on hierarchical Archimedean copulae (HAC) with up to three parameters, with default intensities calibrated to market data and with random loss given defaults that are correlated with default times. The methods presented are used to reproduce the spreads of the iTraxx Europe tranches. Our approach describes the market prices better than the standard pricing procedure based on the Gaussian distribution. We also obtain a flat correlation smile across tranches thereby solving the implied correlation puzzle.     

Looking Beyond Credit Ratings: Factors Investors Consider In Pricing European Asset‐Backed Securities

In this paper, we empirically investigate what credit factors investors rely upon when pricing the spread at issue for European asset‐backed securities. More specifically, we investigate how credit factors affect new issuance spreads after taking into account credit rating. We do so by investigating primary market spreads for tranches of non‐mortgage‐related asset‐backed securities issued from 1999 to the year prior to the subprime mortgage crisis, 2007. We find that although credit ratings play a major role in determining spreads, investors appear to not rely exclusively on these ratings. Our findings strongly suggest that investors do not ignore other credit factors beyond the assigned credit rating.     

Did investors outsource their risk analysis to rating agencies? Evidence from ABS-CDOs

Based on a sample of 3254 floating rate tranches from 617 ABS-CDOs (collateralized debt obligations backed by asset-backed securities), this paper tests the “rating overdependence” hypothesis – i.e., that ratings of structured products are a sufficient statistic (in terms of predicting future credit performance) for yield spreads at origination. The paper’s findings are fourfold. First, yield spreads at issuance predict future performance of ABS-CDO tranches even after controlling for the information contained in ratings. Second, the ability of yield spreads to predict future performance, however, is driven exclusively by ratings below AAA (and, to a lesser extent, also by the lowest priority AAA tranches), whereas spreads of super senior AAA tranches show no information content. Third, the predictive ability of yield spreads is lower for tranches from later vintages and for tranches from deals with more complex collateral pools. Fourth, the conditional correlation between ratings and spreads, in turn, is increasing in time and higher for tranches from complex deals. In sum, the evidence indicates that investors in (especially AAA) tranches from later and more complex deals have avoided performing costly due diligence on the securities they bought.     

Tranching and Rating

In this paper we analyse the source and magnitude of marketing gains from selling structured debt securities at yields that reflect only their credit ratings, or specifically at yields on equivalently rated corporate bonds. We distinguish between credit ratings that are based on probabilities of default and ratings that are based on expected default losses. We show that subdividing a bond issued against given collateral into subordinated tranches can yield significant profits under the hypothesised pricing system. Increasing the systematic risk or reducing the total risk of the bond collateral increases the profits further. The marketing gain is generally increasing in the number of tranches and decreasing in the rating of the lowest rated tranche.     

Competition in the credit rating Industry: Benefits for investors and issuers

We empirically investigate the benefits of multiple ratings not only at issuance of debt instruments but also during the subsequent monitoring phase. Using a record of monthly credit rating migration data on all U.S. residential mortgage-backed securities rated by Standard & Poor's, Moody's, and Fitch between 1985 and 2012 (154,600 tranches), our results provide empirical evidence that rating agencies put more effort in rating and outlook revisions when tranches have assigned multiple ratings. Furthermore, we see that in the case of multiple ratings, agencies do a better job in discriminating tranches with respect to default risk. On the downside, we observe a shift in collateral towards senior tranches and incentives for issuers to engage in rating shopping activities, but find no evidence that rating agencies exploit such behavior to attract more rating business. Our results contribute to the literature on information production of credit ratings and extend the perspective to the monitoring period after issuance.     

The information content of three credit ratings: the case of European residential mortgage-backed securities

We assess the information content of three credit ratings for tranches of newly issued European residential mortgage-backed securities. We find that tranches rated by three credit rating agencies where the rating by Standard & Poor's (S&P's) Ratings Service or Fitch is inferior to Moody's lead to higher funding costs and reflects what we refer to as rating risk. Our results suggest that market participants do not view credit ratings by Fitch and S&P's as redundant despite the fact that both employ the same rating approach.     

Collateral pricing

We examine how collateral affects the cost of debt capital. Using a novel data set of secured debt issued by U.S. airlines, we construct industry-specific measures of collateral redeployability. We show that debt tranches that are secured by more redeployable collateral exhibit lower credit spreads, higher credit ratings, and higher loan-to-value ratios—an effect which our estimates show to be economically sizeable. Our results suggest that the ability to pledge collateral, and in particular redeployable collateral, lowers the cost of external financing and increases debt capacity.     

An analytical approach for systematic risk sensitivity of structured finance products

The global financial crisis has shown that many financial institutions dealing with credit derivatives were exposed to severe unexpected losses. This indicates that systematic influences are decisively underestimated particularly with regard to structured products like securitized tranches of collateralized debt obligations. Our analytical study addresses these systematic effects: We provide a simple model which allows a closed-form comparison of both bonds and tranches with respect to their systematic risk. We demonstrate that the exposure to systematic risk of tranches may be many times higher than the exposure of bonds, even if both products share the same rating grade, e.g., an ‘AAA’ rating, measured by either default probability or expected loss. Particularly in economic downturns, default rates of tranches may be multiples of those of bonds. Our results help understand high default rates of tranches during the financial crisis and show that classical ratings are insufficient metrics for measuring risks of structured products.     

Delta-hedging correlation risk?

While the Gaussian copula model is commonly used as a static quotation device for CDO tranches, its use for hedging is questionable. In particular, the spread delta computed from the Gaussian copula model assumes constant base correlations, whereas we show that the correlations are dynamic and correlated to the index spread. It might therefore be expected that a dynamic model of credit risk, which is able to capture the dependence between the base correlations and the index spread, will have better hedging performances. In this paper, we compare delta hedging of spread risk based on the Gaussian copula model, to the implementation of jump-to-default ratio computed from the dynamic local intensity model. Theoretical and empirical analysis are illustrated by using the market data in both before and after the subprime crisis. We observe that delta hedging of spread risk outperforms the implementation of jump-to-default ratio in the pre-crisis period associated with CDX.NA.IG series 5, and the two strategies have comparable performance for crisis period associated with CDX.NA.IG series 9 and 10. This shows that, although the local intensity model is a dynamic model, it is not sufficient to explain the joint dynamic of the index spread and the base correlations, and a richer dynamic model is required to obtain better hedging results. Moreover, although different specifications of the local intensity can be fitted to the market data equally well, their hedging results can be significant different. This reveals substantial model risk when hedging CDO tranches.     

Recognition versus disclosure of finance leases: Evidence from Japan

This study examines whether credit market participants—bond investors and credit rating agencies—treat recognized and disclosed finance leases differently when assessing firms’ credit risk in Japan. I use firms’ credit risk, measured by bond spreads and credit ratings, to investigate the relations between recognized versus disclosed finance lease obligations and firms’ credit risk following the adoption of Statement No. 13, Accounting Standard for Lease Transactions. For a sample of firms issuing new bonds, I find that, unlike recognized finance leases, disclosed finance leases are not associated with bond spreads. Moreover, the associations between recognized versus disclosed finance leases and bond spreads are substantially different. Conversely, recognized and disclosed finance leases are associated with credit ratings and are processed similarly when credit ratings are determined. Taken together, my results suggest that the sophistication of capital market participants influences their credit risk assessments of recognized versus disclosed finance leases.     

Pricing distressed CDOs with stochastic recovery

In this article, a framework for the joint modelling of default and recovery risk in a portfolio of credit risky assets is presented. The model especially accounts for the correlation of defaults on the one hand and correlation of default rates and recovery rates on the other hand. Nested Archimedean copulas are used to model different dependence structures. For the recovery rates a very flexible continuous distribution with bounded support is applied, which allows for an efficient sampling of the loss process. Due to the relaxation of the constant 40% recovery assumption and the negative correlation of default rates and recovery rates, the model is especially suited for distressed market situations and the pricing of super senior tranches. A calibration to CDO tranche spreads of the European iTraxx portfolio is performed to demonstrate the fitting capability of the model. Applications to delta hedging as well as base correlations are presented.     

Economic value in tranching of syndicated loans

This paper presents a theory to explain the economic value of tranching and provides empirical evidence to support the theoretical implications. I show that riskier firms are more likely to take loans with multiple tranches. Therefore, the average credit spread on a syndicated loan with multiple tranches is higher than that on a non-tranched loan. However, after accounting for the risk characteristics of a tranched loan, I show that borrowings that are a part of tranched loans have lower credit spreads than otherwise identical non-tranched loans. I also show that the benefits of tranching accrue primarily to riskier borrowers.     

Contagion models a la carte: which one to choose?

We propose a copula contagion mixture model for correlated default times. The model includes the well-known factor, copula, and contagion models as its special cases. The key advantage of such a model is that we can study the interaction of different models and their pricing impact. Specifically, we model the default times of the underlying names in a reference portfolio to follow contagion intensity processes with exponential decay coupled with a copula dependence structure. We also model the default time of the counterparty and its dependence structure with the reference portfolio. Numerical tests show that correlation and contagion have an enormous joint impact on the rates of CDO tranches and the corresponding credit value adjustments are extremely high to compensate for the wrong-way risk.     

Hedging structured credit products during the credit crisis: A horse race of 10 models

Pricing and hedging structured credit products poses major challenges to financial institutions. This paper puts several valuation approaches through a crucial test: How did these models perform in one of the worst periods of economic history, September 2008, when Lehman Brothers went under? Did they produce reasonable hedging strategies? We study several bottom-up and top-down credit portfolio models and compute the resulting delta hedging strategies using either index contracts or a portfolio of single-name CDS contracts as hedging instruments. We compute the profit-and-loss profiles and assess the performances of these hedging strategies. Among all 10 pricing models that we consider the Student-t copula model performs best. The dynamical generalized-Poisson loss model is the best top-down model, but this model class has in general problems to hedge equity tranches. Our major finding is however that single-name and index CDS contracts are not appropriate instruments to hedge CDO tranches.     

Pricing structured products with economic covariates

We introduce a top-down no-arbitrage model for pricing structured products. Losses are described by Cox processes whose intensities depend on economic variables. The model provides economic insight into the impact of structured products on financial institutions’ risk exposure and systemic risk. We estimate the model using CDO data and find that spreads decrease with higher interest rates and increase with volatility and leverage. Volatility is the primary determinant of variation in tranche spreads. Leverage and interest rates are more closely associated with rare credit events. Model-implied risk premiums and the probabilities of tranche losses increase substantially during the financial crisis.     

Market share and risk taking: the role of collateral asset managers in the collapse of the arbitrage CDO market

Asset pricing theory predicts that if credit ratings do not reflect all relevant aspects of a CDO debt tranche’s risk profile (i.e., its total and systematic risk), then ratings-based tranche pricing by some naïve investors creates incentives for CDO arrangers to take excessive non-priced risk. CDO managers’ desire for repeat issuance makes them part of this risk taking strategy to exploit naïve investors. The implication is that the credit quality of CDOs run by large market share managers has a higher tendency to deteriorate in bad times. This paper finds empirical evidence for large market share manager’s conflicts of interest.