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.     

CDOs and the financial crisis: Credit ratings and fair premia

We study risk and return characteristics of CDOs using the market standard models. We find that fair spreads on CDO tranches are much higher than fair spreads on similarly-rated corporate bonds. Our results imply that credit ratings are not sufficient for pricing, which is surprising given their central role in structured finance markets. This illustrates limitations of the rating methodologies that are solely based on real-world default probabilities or expected losses and do not capture risk premia. We also demonstrate that CDO tranches have large exposure to systematic risk and thus their ratings and prices are likely to decline substantially when credit conditions deteriorate.     

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.     

Securitization bubbles: Structured finance with disagreement about default risk

An additional reason for the structured finance boom of the 2000s may have been disagreement about default risk of collateral assets. When risk-neutral investors disagree about average default probabilities, structuring collateral cash flow raises prices by concentrating optimists’ demand on risky tranches. With disagreement about default correlation, low-correlation investors believe in diversification and pay high prices for senior tranches they deem riskless. High-correlation investors value junior tranches they expect to pay whenever aggregate conditions are good. Risk aversion and short selling through credit default swaps reduce the prices of both pass-through and structured securitizations but may increase the return to tranching.     

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.     

THE INFORMATIONAL ROLE OF BANK LOAN RATINGS

We analyze the relatively new phenomenon of credit ratings on syndicated loans, asking first whether they convey information to the capital markets. Our event studies show that initial loan ratings and upgrades are not informative, but downgrades are. The market anticipates downgrades to some extent, however. We also examine whether public information reflecting borrower default characteristics explains cross‐sectional variation in loan ratings and find that ratings are only partially predictable. Our evidence suggests that loan and bond ratings are not determined by the same model. Finally, we estimate a credit spread model incorporating bank loan ratings and other factors reflecting default risk, information asymmetry, and agency problems. We find that ratings are related to loan rates, given the effect of other influences on yields, suggesting that ratings provide information not reflected in financial information. Ratings may capture idiosyncratic information about recovery rates, as each of the agencies claims, or information about default prospects not available to the market.     

Are All Ratings Created Equal? The Impact of Issuer Size on the Pricing of Mortgage‐Backed Securities

Initial yields on both AAA‐rated and non‐AAA rated mortgage‐backed security (MBS) tranches sold by large issuers are higher than yields on similar tranches sold by small issuers during the market boom years of 2004 to 2006. Moreover, the prices of MBS sold by large issuers drop more than those sold by small issuers, and the differences are concentrated among tranches issued during 2004 to 2006. These results suggest that investors price the risk that large issuers received more inflated ratings than small issuers, especially during boom periods.     

Split Bond Ratings and Information Opacity Premiums

This paper examines the relationship between split bond ratings and bond yields at the notch level for newly issued corporate bonds. We find that split rated bonds average a 7-basis-point yield premium over nonsplit rated bonds of similar credit risk. The yield premium increases from 5 basis points for one-notch splits to 15 (20) basis points for two-notch (three-notch) splits. These findings indicate that investors demand higher yields for split rated bonds to compensate for the information opacity of such bonds. In addition, the yield premium for split rated bonds is higher during economic recessions, indicating investors are more risk averse during economic downturns. Consequently, split ratings impose higher borrowing costs for firms, especially during economic downturns.     

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.     

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.     

A re-examination of the impact of credit ratings and economic factors on state bond yields

In this article we re-examine the impact of credit ratings and economic factors on state bond yields using a two-step model. In the first step, we adopt an ordered probit technique to obtain consistent estimates of state bond default risk. In the second step, we estimate state bond risk premiums using a regression analysis with a categorized risk variable obtained from the first step. Similar to Terza (1987) and Hsiao (1983), the model involves a categorized ordinal explanatory (rating) variable. However, our two-step model deals with a case where category thresholds are unknown and dependent on economic factors. The model provides consistent estimates for the effects of ratings and economic factors on state bond yields. Contrary to previous findings, we find that state bond yields are mainly affected by fundamental economic variables.     

Credit default swaps and the market for sovereign debt

In this paper, we analyze the determinants and effects of credit default swap (CDS) trading initiation in the sovereign bond market. CDS trading initiation is associated with a 30–150 basis point reduction in sovereign bond yields, with greater yield reductions accruing to higher default risk economies. For countries with high default risk, rated B or lower by Standard and Poor’s, CDS initiation is also associated with significant price efficiency benefits in the underlying market. CDS trading initiation is more likely following increases in local equity index volatility, index spreads for regional and global CDS markets, or depreciation of the local currency relative to the US dollar, and decreases in a country’s ability to service foreign debt. Our results are robust to selection bias controls based on these factors.     

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.     

Credit ratings and structured finance

The poor performance of credit ratings of structured finance products in the financial crisis has prompted investigation into the role of credit rating agencies (CRAs) in designing and marketing these products. We analyze a two-period reputation model in which a CRA both designs and rates securities that are sold both to investors who are constrained to purchase highly rated securities and investors who are unconstrained. Assets are pooled and senior and junior tranches are issued with a waterfall structure. When the rating constraint is lax, the CRA will include only risky assets in the securitization pool, serving both types of investors without any rating inflation. Rating inflation is decreasing in the tightness of the rating constraint locally. But rating inflation may be non-monotonic in the rating constraint globally, with no rating inflation when the constraint is lax or tight.     

Rating friends: The effect of personal connections on credit ratings

Using a large sample of US public debt issues we show that personal connections between directors of issuing companies and rating agencies result in higher credit ratings. We estimate the average effect to be about one notch. Moreover, our tests indicate that issues by connected firms are 30% more likely to be rated A3. Results are robust to several alternative tests including additional controls for managerial traits, firm fixed effects, and propensity score matching. Furthermore, our tests on default rates and bond yields suggest that personal connections act as a mechanism to reduce asymmetric information between the rating agency and the issuer.     

On the consistency of ratings and bond market yields

We study the consistency of the credit-risk orderings implicit in ratings and bond market yields. By analyzing errors in term structure estimates for bonds with particular ratings, we show that for significant periods, a quarter of some categories of high credit quality bonds are rated in a manner that is inconsistent with their pricing. Adjusting for economic determinants of spreads (tax, liquidity and risk premiums) and allowing for the dynamic adjustment of ratings and spreads largely eliminates the inconsistencies, however.     

中债估值识别了债券信用风险吗？——基于跳跃视角的实证分析

本文以2011—2018年中国A股上市公司发行的一般公司债为样本,探究了中债估值跳跃对债券信用利差的影响及作用机制,以此说明中债估值对债券信用风险的识别作用。研究发现:中债估值跳跃能够显著提高债券信用利差,其中,中债估值上跳降低了信用利差,下跳提高了信用利差,且相对于上跳,下跳对信用利差的作用更大。异质性分析发现:中债估值跳跃对信用利差的作用在机构投资者中较大,同时在信息不对称性较严重、流动性较差及违约风险较高的债券中也较大。进一步研究发现:中债估值跳跃不仅包含了公共信息,还含有私有信息,并能改善股票分析师预测表现。本研究说明中债估值能够识别债券信用风险,具有信息含量,对于债券市场信息环境建设和系统性金融风险防范具有重要意义。     

Copula dynamics in CDOs

Values of tranche spreads of collateralized debt obligations (CDOs) are driven by the joint default performance of the assets in the collateral pool. The dependence between the entities in the portfolio mainly depends on current economic conditions. Therefore, a correlation implied from tranches can be seen as a measure of the general situation of the credit market. We analyse the European market of standardized CDOs using tranches of the iTraxx index in the periods before and during the global financial crisis. We investigate the evolution of the correlations using different copula models: the standard Gaussian, the NIG, the double-t, and the Gumbel copula model. After calibration of these models, one obtains a time varying vector of parameters. We analyse the dynamic pattern of these coefficients. That enables us to forecast future parameters and consequently calculate Value-at-Risk measures for iTraxx Europe tranches.     

A comparative study of the probability of default for global financial firms

This article presents a modification of Merton’s (1976) ruin option pricing model to estimate the implied probability of default from stock and option market prices. To test the model, we analyze all global financial firms with traded options in the US and focus on the subprime mortgage crisis period. We compare the performance of the implied probability of default from our model to the expected default frequencies based on the Moody’s KMV model and agency credit ratings by constructing cumulative accuracy profiles (CAP) and the receiver operating characteristic (ROC). We find that the probability of default estimates from our model are equal or superior to other credit risk measures studied based on CAP and ROC. In particular, during the subprime crisis our model surpassed credit ratings and matched or exceeded KMV in anticipating the magnitude of the crisis. We have also found some initial evidence that adding off-balance-sheet derivatives exposure improves the performance of the KMV model.     

Tempered stable structural model in pricing credit spread and credit default swap

In this paper, we explore the features of a structural credit risk model wherein the firm value is driven by normal tempered stable (NTS) process belonging to the larger class of Lévy processes. For the purpose of comparability, the calibration to the term structure of a corporate bond credit spread is conducted under both NTS structural model and Merton structural model. We find that NTS structural model provides better fit for all credit ratings than Merton structural model. However, it is noticed that probabilities of default derived from the calibration of the term structure of a bond credit spread might be overestimated since the bond credit spread could contain non-default components such as illiquidity risk or asymmetric tax treatment. Hence, considering CDS spread as a reflection of the pure credit risk for the reference entity, we calibrate it in order to obtain more reasonable probability of default and obtain valid results in calibration of the market CDS spread with NTS structural model.