Rating the raters: Are reputation concerns powerful enough to discipline rating agencies?

Credit rating agencies (CRAs) are accused of bearing a strong responsibility for contributing to the subprime crisis by having been deliberately too lax in the ratings of some structured products. In response to this accusation, CRAs argue that such an attitude would be too dangerous for them, since their reputation is at stake. The objective of this article is to examine the validity of this argument within a formal model: Are reputation concerns sufficient to discipline rating agencies?We show that the reputation argument only works when a sufficiency large fraction of the CRA income comes from other sources than rating complex products. By contrast when rating complex products becomes a major source of income for the CRA, we show that it is always too lax with a positive probability and inflates ratings with probability one when its reputation is good enough.We provide some empirical support for this prediction, by showing that ceteris paribus, the proportion of subprime residential mortgage-backed securities (RMBS) that were rated AAA by the three main CRAs indeed increased over the last eight years.We analyze the policy implications of our findings and advocate for a new business model of CRAs that we call the platform-pays model.     

私有信息、评级偏差和中国评级机构的市场声誉

考虑到评级机构拥有市场声誉的本质在于其可以通过扭曲评级从而对市场产生影响,本文分两步研究中国发行人付费评级机构的市场声誉:第一步,将信用评级对各种基本面因素进行回归,并以实际评级与回归预测值的差值作为评级偏差的量度。与既有文献相比,本文的重要改进是在基本面因素中引入了发债企业与各评级机构(分支机构)最短距离的均值和方差,这能较好地控制因发债企业私有信息可能造成的选择偏误。第二步,考察评级偏差和机构特征如何影响企业的发债成本。研究表明,中国评级机构作为一个整体具有显著的市场声誉,但各评级机构之间存在很大的差异性。最后,考虑到评级机构与发债企业在选址上可能会有集聚效应,我们基于高铁开通事件进行双重差分检验,研究表明本文结论是稳健的。     

信用评级变动能反映企业真实财务信息吗?——基于财务重述的视角

本文以2007-2018年拥有主体信用评级的A股上市公司为研究对象,利用企业财务错报在未来被重述这一场景,检验主体信用评级变动能否反映企业真实财务信息。研究发现,评级机构在发债企业财务错报年显著下调了主体信用评级,而在重述公告发布年没有上述现象,这表明主体信用评级下调反映了企业的真实财务信息。在控制内生性影响后,结论仍然成立。进一步研究发现,发债企业当期财务错报涉及盈余时,主体信用评级被下调的幅度更大,说明评级机构更加关注与盈余相关的财务信息。机制分析表明,评级机构维护自身声誉是主体信用评级变动能够反映企业真实财务信息的主要机制。此外,主体信用评级被下调还导致了资本市场投资者的负面反应。本文的研究结果为主体信用评级变动反映企业真实财务信息提供了直接的证据支持,揭示了主体信用评级的信息含量,也对理解中国情境下评级机构调整主体信用评级的行为动机提供参考。     

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.     

金融中介机构竞争的市场反应--来自信用评级机构的证据北大核心

目前已有研究认为金融中介机构竞争会带来市场效率的提高,本文利用2012-2017年债券市场的微观数据研究“发行人付费”模式评级机构之间的竞争对评级结果的影响。研究发现,评级机构竞争会导致评级结果膨胀与评级质量下降。进一步研究发现,当评级竞争加剧时,“发行人付费”模式的评级机构会对有较多业务联系的企业放松评级标准,给予更高信用评级。我们的研究也发现评级机构的外资背景、承销商的良好声誉和媒体关注均有助于减小“发行人付费”模式下评级机构竞争的负面影响。同时,债券市场评级竞争还存在对股票市场的溢出效应,评级竞争导致的评级质量下降也降低了股票市场的信息效率。这说明,“发行人付费”模式下的评级机构竞争会降低资本市场的信息效率,“投资者付费”模式的推广和评级行业的对外开放有助于改善国内评级行业的评级质量。本文的研究也为国内债券市场进一步发挥双评级、多评级以及不同模式评级的交叉验证作用提供了一定证据支持。     

债券评级机构变更——基于评级选购与评级迎合视角

本文以2008年至2017年的公司债券为样本,研究了发行人变更评级机构的影响,以此来解释评级市场上发行人频繁变更评级机构的现象。本文发现发行人变更评级机构后,其信用等级得到显著提升。发行人变更评级机构的行为对信用等级的影响在以下两种情形中更显著:一是当发行人所处行业或评级机构所在的评级市场竞争激烈时;二是当发行人主体评级位于AA信用等级的临界点时。进一步研究发现,考虑到评级机构变更与信用等级之间的交互影响,变更评级机构的发行人整体上可实现发债成本的降低。但该类发行人未来的违约风险增加、经营业绩下降。最后,本文发现债券发行规模较大以及非国有发行人更倾向于变更评级机构来提高信用等级。本文通过分析发行人更换信用评级机构的动机和后果,为监管部门构建以评级质量为导向的良性竞争环境提供借鉴参考。     

Does reputation matter? Evidence on spatial competition in China's bond market

This study investigates the effect of market competition on the reputational concerns of credit rating agencies (CRAs) in the Chinese bond market. We find credit ratings increase when the market share distance between an incumbent CRA and its closest peer competitor decreases. This spatial competition effect only exists at the provincial level. We also find the market competition deteriorates the ability of ratings to predict future bond defaults, while the correlation between credit ratings and market-implied credit spreads is unaffected. Our findings suggest that because of the market inefficiency in emerging economies, CRAs privilege current profits over reputational concerns.     

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.     

Credit Rating Inflation and Firms' Investments

We analyze credit rating effects on firm investments in a rational bond financing game that features a feedback loop. The credit rating agency (CRA) inflates the rating, providing a biased but informative signal to creditors. Creditors' response to the rating affects the firm's investment decision and thus its credit quality, which is reflected in the rating. The CRA might reduce ex ante economic efficiency, which results solely from its strategic effect: the CRA assigns more firms high ratings and allows them to gamble for resurrection. We derive empirical predictions on the determinants of rating standards and inflation and discuss policy implications.     

多重信用评级与债券融资成本——来自中国债券市场的经验证据

本文揭示了多重信用评级的信息生产机制和信用认证机制,排除了“信用评级购买”假说对于多重评级动机的解释,研究发现:多重信用评级有利于降低债券融资成本;相对于不一致的多重信用评级,一致的多重信用评级更有利于降低债券融资成本。在多重信用评级中,相对于评级机构均为“发行人付费”模式,兼有“投资者付费”模式的信用评级更有利于降低债券融资成本。此外,当多重信用评级的评级意见不一致时,平均评级的信息含量最高,即综合不同信用评级所包含的多种信息比任何单一信用评级更加具有信息含量。本研究为我国债券市场双评级制度提供了理论和经验证据的支持,有助于完善多元化信用评级制度和债券市场监管制度,并提示发债企业可以通过多重信用评级向市场传递更多和更具效度的评级信息,以弥补单一信用评级的信息不足和评级结果失准,减少投资者决策的不确定性,从而降低债券融资成本。     

Credit Ratings as Coordination Mechanisms

In this article, we provide a novel rationale for credit ratings.The rationale that we propose is that credit ratings serve asa coordinating mechanism in situations where multiple equilibriacan obtain. We show that credit ratings provide a "focal point"for firms and their investors, and explore the vital, but previouslyoverlooked implicit contractual relationship between a creditrating agency (CRA) and a firm through its credit watch procedures.Credit ratings can help fix the desired equilibrium and as suchplay an economically meaningful role. Our model provides severalempirical predictions and insights regarding the expected priceimpact of rating changes.     

Quantitative easing and credit rating agencies

This paper investigates the behaviour of credit rating agencies (CRAs) using a natural experiment in monetary policy. We exploit the corporate QE of the Eurosystem and its rating-based specific design which generates exogenous variation in the probability for a bond of becoming eligible for outright purchases. We show that after the launch of the policy, rating activity was concentrated precisely on the territory where the incentives of market participants are expected to be more sensitive to the policy design. Our findings contribute to better assessing the consequences of the explicit reliance on CRAs ratings by central banks when designing monetary policy.     

Ratings quality over the business cycle

Credit rating agencies (CRAs) have long held that reputational concerns discipline their behavior. The value of reputation, however, depends on economic fundamentals that vary over the business cycle. In a model of ratings incorporating endogenous reputation and a market environment that varies, we find that ratings quality is countercyclical. Specifically, a CRA is more likely to issue less-accurate ratings when fee-income is high, competition in the labor market for analysts is tough, and securities' default probabilities are low. Persistence in economic conditions can diminish our results, while mean reversion exacerbates them. The presence of naive investors reduces overall quality, but quality remains countercyclical. Finally, we demonstrate that competition among CRAs yields similar results.     

Tiebreaker: Certification and Multiple Credit Ratings

This paper explores the economic role credit rating agencies play in the corporate bond market. We consider three existing theories about multiple ratings: information production, rating shopping, and regulatory certification. Using differences in rating composition, default prediction, and credit spread changes, our evidence only supports regulatory certification. Marginal, additional credit ratings are more likely to occur because of, and seem to matter primarily for, regulatory purposes. They do not seem to provide significant additional information related to credit quality.     

A sparsity algorithm for finding optimal counterfactual explanations: Application to corporate credit rating

Machine learning methods used in finance for corporate credit rating lack transparency as to which accounting features are important for the respective rating. A counterfactual explanation is a methodology that attempts to find the smallest modification of the input values which changes the prediction of a learned algorithm to a new output, other than the original one. We propose a “sparsity algorithm” which finds a counterfactual explanation to find the most important features for obtaining a higher credit score. We validate the novel algorithm with synthetically generated data and we apply it to quarterly financial statements from companies in the US market. We provide evidence that the counterfactual explanation can capture the majority of features that change between two quarters when corporate ratings improve. The results obtained show that the higher the rating of a company, the greater the “effort” required to further improve credit rating.     

Did going public impair Moody׳s credit ratings?

We investigate a prominent allegation in congressional hearings that Moody?s loosened its rating standards to chase revenue after it went public in 2000. Consistent with this allegation, Moody?s ratings for both corporate bonds and structured finance products are significantly more favorable to issuers, relative to S&P?s, after Moody?s IPO. Moreover, Moody?s ratings are more favorable for clients subject to greater conflict of interest. There is little evidence that Moody?s higher ratings, post-IPO, are more informative, measured as expected default frequencies (EDFs) or as the probability of default. Our findings inform the debate on whether financial gatekeepers should be publicly traded.     

Is less information better information? Evidence from the credit rating withdrawal

This paper examines the stock market reaction to two different types of credit rating withdrawals by Moody’s. The first type of withdrawal occurs when a firm stops being rated. This happens, for example, when firms choose to no longer pay for a rating. We find that the stock market reaction depends on the information which remains available. The second type of withdrawal is due to Moody’s policy of removing the issuer rating and keeping the corporate family rating for the same firm. The corporate family rating is usually more favorable than the issuer rating. The paper shows that the removal of the issuer rating leads to positive stock market reaction. We conclude that lower disclosure of rating information is not necessarily associated with higher cost of equity. Instead, our findings emphasize the incentive for firms to engage in ratings shopping by publishing only the most favourable ratings.     

Information effect of entry into credit ratings market: The case of insurers' ratings

The paper analyzes the effect of competition between credit rating agencies (CRAs) on the information content of ratings. We show that a monopolistic CRA pools sellers into multiple rating classes and has partial market coverage. This provides an opportunity for market entry. The entrant designs a rating scale distinct from that of the incumbent. It targets higher-than-average companies in each rating grade of the incumbent's rating scale and employs more stringent rating standards. We use Standard and Poor's (S&P) entry into the market for insurance ratings previously covered by a monopolist, A.M. Best, to empirically test the impact of entry on the information content of ratings. The empirical analysis reveals that S&P required higher standards to assign a rating similar to the one assigned by A.M. Best and that higher-than-average quality insurers in each rating category of A.M. Best chose to receive a second rating from S&P.     

Sovereign ceilings “lite”? The impact of sovereign ratings on corporate ratings

Although credit rating agencies have gradually moved away from a policy of never rating a corporation above the sovereign (the ‘sovereign ceiling’), it appears that sovereign credit ratings remain a significant determinant of corporate credit ratings. We examine this link using data for advanced and emerging economies over the period of 1995–2009. Our main result is that a sovereign ceiling continues to affect the rating of corporations. The results also suggest that the influence of a sovereign ceiling on corporate ratings remains particularly significant in countries where capital account restrictions are still in place and with high political risk.     

债券市场的评级信息能改善股票市场信息环境吗?——来自分析师预测的证据

本文研究发现,信用评级增加了分析师预测的公共信息,同时没有减少分析师预测的私有信息,即信用评级信息能够改善股票市场信息环境。具体地,本文利用2006-2016年上市公司数据实证发现,信用评级能显著提高分析师预测精度、降低分析师预测分歧度与乐观偏差,且这种效应在信息不对称程度高、低能力分析师跟踪的企业以及外资参股的评级机构中更加显著,这说明信用评级向分析师提供了新的信息。进一步地,信用评级只增加了分析师预测的公共信息,对私有信息没有显著影响,同时也不影响分析师的调研行为,上述结论表明信用评级信息披露并不影响分析师拥有私有信息的优势,且信用评级机构与分析师之间存在互补而非替代关系。因此,金融监管应该加强对评级机构尽职调研的要求,充分发挥信用评级机构的信息中介功能。