主权信用评级对证券市场的影响研究述评

国际证券市场的持续动荡,使得主权信用评级的影响作用越加突现。诸多研究指出,主权信用评级调整对股票市场和债券市场都存在影响,但由于市场对信息的敏感程度不同,股票市场比债券市场的反应剧烈,而且股票市场对主权信用评级调整能作出提前响应。由于市场预期和经济周期的合力作用,市场存在着对正负评级变化的不对称反应。因此,对现有文献进行梳理和评议,一方面增进了人们对这一问题的认识和理解,另一方面也为制定风险防范政策提供了一定的参考依据。     

Determinants of the distance between sovereign credit ratings and sub-sovereign bond ratings: Evidence from emerging markets and developing economies

This article explores factors that affect the distance between sovereign credit ratings and the ratings assigned to new foreign-currency bonds issued by sub-sovereign entities (such as private non-financial corporations, financial firms, and public sector enterprises) in 47 emerging markets and developing economies. Censored and double-hurdle regression models are used to estimate the relative contributions of bond-level, issuer-level, and macroeconomic factors that determine this distance, separately for those rated at or below the sovereign rating and those rated above. For the three quarters or more of sub-sovereign bond ratings that are constrained by the sovereign rating ceiling, a Tobit regression model shows a smaller distance – suggesting stronger sovereign–corporate linkages – for public sector enterprises and financial firms relative to other firms. Riskier global financial conditions are also associated with sub-sovereign bonds being rated closer to the sovereign rating. For the small number of sub-sovereign bonds rated higher than the sovereign rating, a double-hurdle model shows that certain debt features – such as bonds backed by future-flow receivables or other collateral or structured as Special Purpose Vehicles (SPV) – significantly raise the likelihood of piercing the sovereign rating ceiling and also increase the distance above the sovereign ceiling.     

Credit ratings and bond spreads of the GIIPS

We examine the relationship between credit ratings and bond yield spreads of peripheral countries in the euro area (Greece, Ireland, Italy, Portugal and Spain) for the period 1995–2014. Since 2012, bond spreads of those countries have come down very fast, whereas credit ratings have hardly changed. Our results suggest that credit rating agencies have become more cautious and have changed their approach to assess credit risk of sovereigns, and that the impact of sovereign credit risk ratings on sovereign bond spreads has changed.     

国家主权信用评级、跨国传染与股票市场回应?--基于全球48个经济体的事件研究

掌握主权信用评级变动的市场影响及其传染机制,对于投资者、国家金融安全及政府采取应对措施来说都意义重大。文章采用事件研究法,以1990-2013年全球48个经济体发生的评级事件和每日股指收益率数据为样本,实证研究了事件国评级变动对非事件国股票市场的影响及其传染渠道,结果表明：(1)评级下调会对股票市场产生显著为负的超额收益,但评级上调产生的超额收益不显著;(2)股票市场可以提前预测评级下调事件,但不能预测评级上调事件;(3)季风效应对评级调整的市场传染有一定的解释力;(4)净传染效应基本不显著,这说明评级事件的市场传染应该有经济基础,而不是由投资者心理预期这类非基本面因素造成的;(5)溢出效应可以较好地解释评级的市场传染,是评级变动影响市场及传染的主要渠道。文章的结论深化了我们对评级调整如何影响股票市场及其传染渠道的认识,也为中国防范国外主权信用评级变动风险提供了有益启示。     

European policy and markets: Did policy initiatives stem the sovereign debt crisis in the euro area?

We investigate how European policy initiatives influenced market assessments of sovereign default risk and banking sector fragility during the sovereign debt crisis in four adversely affected countries — Portugal, Ireland, Spain and Italy. We focus on three broad groups of policies: (a) ECB policy actions (monetary and financial support), (b) EU programs (financial and fiscal rules as well as financial support in crisis countries), and (c) domestic austerity programs. We measure immediate market impact effects: what policies changed risk perceptions, using CDS spreads on sovereign bonds and banks in this assessment. We employ dynamic panel and event study methodologies in the empirical work. We find that a number of programs initially stabilized sovereign and bank bond markets (e.g. Outright Monetary Transactions program), although announcement and implementation impacts on markets differed in some cases (e.g. second Covered Market Bond Program). Actions designed to shore up sovereign markets often lowered risk assessments in bank bond markets and policies designed to ensure safety and soundness of the European banking system in some cases significantly impacted sovereign debt markets. Finally, a number of policies designed to stabilize markets had surprisingly little immediate impact on either sovereign or bank bond market risk assessments.     

Can fiscal rules improve financial market access for developing countries?

A number of countries have introduced fiscal rules to deter fiscal profligacy, enhance the credibility of fiscal policy, and reduce borrowing costs. In this paper, we examine the outcome of fiscal rules in terms of improving financial market access for developing countries. We use entropy balancing and various propensity score matching. We find that the adoption of fiscal rules reduces sovereign bond spreads and increases sovereign debt ratings for a sample of 36 developing countries, which are part of the JP Morgan Emerging Markets Bond Index Global (EMBIG), for the period 1993-2014. We explain this finding by the effect of fiscal rules on the credibility of a country's fiscal policy: more credible governments are rewarded in the international financial markets by low sovereign bond spreads and high sovereign debt ratings. These results are robust to a wide set of alternative specifications. We also show that this favorable effect is sensitive to several country structural characteristics. Our findings confirm that the adoption and sound implementation of fiscal rules is an instrument for policy makers to improve developing countries’ financial market access.     

Moving markets? Government bond investors and microeconomic policy changes

Do sovereign bond markets react systematically to microeconomic policy reforms? Some observers suggest that investors are very attentive to supply‐side policies such as those related to labor markets, corporate taxation, and product standards. They argue that, along with macroeconomic outcomes and broad financial market conditions, such reforms affect sovereign bond premiums, for developed as well as emerging economies. In contrast, we predict few systematic effects of supply‐side policy reforms on sovereign bond market outcomes. Our theory draws on a standard three‐equation model of the economy, widely accepted among economic and finance professionals. That model makes few clear predictions regarding the anticipated effects of microeconomic policy changes; as a result, we expect that such reforms will not generate systematic market reactions. Our analyses, based on daily data from 37 countries from 2004 to 2012, indeed reveal little evidence of a systematic bond market reaction to the 47 most significant reforms to corporate taxation and labor market regulation. These results call into question the notion that “bond market vigilantes” play a central role in compelling governments to enact specific microeconomic policy changes.     

Measuring the Effect of Corruption on Sovereign Bond Ratings

Abstract

Instrumenting for sovereign corruption, we find that Transparency International’s Corruption Perceptions Index which ‘ranges from 10 (highly clean) to 0 (highly corrupt)’, is a significant predictor of the Standard and Poor’s sovereign bond ratings ranging from 1 (Sovereign Default) to 22 (AAA) in panel data from 52 countries from 1993 to 2002. Corruption downgrades the creditworthiness of sovereign bonds by diverting loan proceeds from productive projects to less productive ones, if not to offshore accounts. In particular, a one point worsening of the corruption perception index leads to an estimated one‐notch reduction out of 22 in the sovereign bond rating.     

ECONOMIC FREEDOM AND STATE BOND RATINGS

Are state bond ratings, ceteris paribus, related to economic freedom? We test for the relationship between economic freedom and an aggregate index comprised of ratings by Standard & Poor, Moody's, and Fitch. We also test for a relationship between economic freedom and the ratings by these three agencies individually. With a sample covering all 50 states for the period 1995–2008, the evidence strongly indicates that state bond ratings are positively and significantly related to overall economic freedom as well as three sub‐categories of economic freedom. Our results show that the quantitative impact of economic freedom on bond ratings is comparable to the effect of state real income and the unemployment rate. (JEL E43, H71)     

Assessing Recent Determinants of Borrowing Costs in Sub‐Saharan Africa

This study explores macroeconomic implications of the sovereign bond rush that has been taking place in sub‐Saharan Africa since 2006. The focus is on the sub‐Saharan sovereign bond yields as proxies for the region's ability to raise new funds on international markets. Despite the subcontinent's tour‐de‐force entrance to the international bond market, this paper reveals that recent (since early 2000s) borrowing in foreign currency is not without macroeconomic risk. Empirically this paper finds that sovereign bond yields are significantly influenced by global volatility, commodity prices and global liquidity—all factors that are out of the control of the sub‐Saharan economies in question. These findings suggest that portfolio repositioning by institutional investors prompted by improved growth prospects and implicit monetary policy tightening in the advanced economies or heightened risk perceptions, are likely to result in increased borrowing costs for the sub‐Saharan bond issuers and affect their ability to raise funds in international markets. Furthermore, a change in borrowing costs might lead to higher debt‐service costs and policy uncertainty, which in turn could lead to suboptimal investment levels and, ultimately, hinder economic development.     

How do experts forecast sovereign spreads?

This paper assesses how forecasting experts form their expectations about future government bond spreads. Using monthly survey forecasts for France, Italy and the United Kingdom between January 1993 and October 2014, we test whether respondents consider the expected evolution of the fiscal balance—and other economic fundamentals—to be significant drivers of the expected bond yield differential over a benchmark German 10-year bond. Our main result is that a projected improvement of the fiscal outlook significantly reduces expected sovereign spreads. This suggests that credible fiscal plans affect market experts’ expectations and reduce the pressure on sovereign bond markets. In addition, we show that expected fundamentals generally play a more important role in explaining forecasted spreads compared to realized spreads.     

Sovereign credit ratings,growth volatility and the global financial crisis

Using monthly data from January 1996 to May 2010 for a panel of 76 developed and emerging economies and adopting an instrumental variable (IV) estimation technique by correcting for both heterogeneity and endogeneity with the generalized two-stage least squares (G2SLS, EC2SLS) procedure method suggested by Balestra and Varadharajan-Krishnakumar (1987) and Baltagi and Li (1995), this article provides empirical evidence that volatility of per capita GDP growth is reduced when there are positive changes in credit ratings; in other words when sovereign credit risk improves. To deal with potential simultaneity between sovereign credit ratings and output volatility, a system (3SLS) approach is undertaken, and our findings remain robust. By weakening the volatility dampening effects of ratings changes, it is found that the global financial crisis (GFC) has enhanced macroeconomic volatility. One of the channels via which sovereign rating changes affect growth volatility is the financial markets’ repricing of sovereign default risk that is reflected in sovereign credit default swap (CDS) spreads and its volatility.     

An Empirical Assessment of Sovereign Country Risk in the Black Sea Region

Country risk is recognized as a key factor considered prior to undertaking cross-border economic activity such as an investment or a financial transaction. When the level of country risk is deemed low, commercial and other risks play a more important role in the assessment of the advisability to undertake a cross-border activity. In other cases, country risk levels are significant and may play a decisive role in the assessment of the cross-border activity. By its nature, country risk depends upon perceptions, and as a result both objective measurable factors and subjective issues need to be considered. This study investigates the factors that determine country risk as signalled by a commonly used proxy, the sovereign credit ratings assigned by the major rating agencies. To this end, panel data analysis has been used and applied to three heterogeneous country sub-groups, the Black Sea Economic Cooperation (BSEC) countries, the EU-15, and the Central Europe and Baltic countries, for the period 2004–2013. The results generated suggest that three sets of variables: gross domestic product per capita, debt metrics, and institutional factors, play an instrumental role in explaining country risk across all the sub-groups. However, the individual results for each sub-group provide evidence that sovereign rating agencies focus on particular economic facets of each, and hence, take into account idiosyncratic aspects, structural as well as regional. Therefore, the study also examines those indicators that matter most or have a ‘specific gravity’ in determining sovereign ratings in each country-group, with a particular focus on the BSEC countries.     

Short- and long-run behaviour of long-term sovereign bond yields

We assess the short- and long-run behaviour of long-term sovereign bond yields in OECD countries using a dynamic panel approach to reflect financial and economic integration. Given the existence of cross-country dependence regarding sovereign yields and its determinants, we resort to simulation and bootstrap methods. Results based on the Common Correlated Effect estimator of Pesaran and on Panel Error Correction Models to sort out short- and long-run fiscal developments show that in addition to common movements in sovereign yields, investors also consider country differences arising from specific factors (inflation, budgetary and current account imbalances, real effective exchange rates, and liquidity).     

Elections, Opportunism, Partisanship and Sovereign Ratings in Developing Countries

We empirically examine whether and how opportunistic and partisan political business cycle (“PBC”) considerations explain election‐period decisions by credit rating agencies (“agencies”) publishing developing country sovereign risk‐ratings (“ratings”). Analyses of 391 agency ratings for 19 countries holding 39 presidential elections from 1987–2000, initially suggest that elections themselves prompt rating downgrades consistent with opportunistic PBC considerations, that incumbents are all likely to implement election‐period policies detrimental to post‐election creditworthiness. But more refined analyses, integrating both opportunistic and partisan PBC considerations in a unified framework, suggest that election‐period agency downgrades (upgrades) are more likely as right‐wing (left‐wing) incumbents, become more vulnerable to ouster by challengers. Together, these results underscore the importance of integrating both opportunistic and partisan PBC considerations into any explanation of election‐period risk assessments of agencies and, perhaps, other private, foreign‐based financial actors important to the pricing and allocation of capital for lending and investment in the developing world.     

The impact of sovereign risk on bond duration: Evidence from Asian sovereign bond markets

This paper examines the effect of sovereign risk on bond duration. We compare the sovereign risk-adjusted duration for U.S. dollar-denominated Asian sovereign bonds with their Macaulay duration for both investment grade bonds and speculative grade bonds. We find that the sovereign risk-adjusted duration is significantly shorter than its Macaulay counterpart for all bonds, regardless of their bond rating and their maturity. Further, the “shortening” effect of sovereign risk on duration gets stronger as bond rating deteriorates and in recessionary conditions. Our findings provide strong support for the importance of adjusting for sovereign risk when bond portfolio managers apply the popular duration measure to hedge interest rate risk.     

PIGS or Lambs? The European Sovereign Debt Crisis and the Role of Rating Agencies

This paper asks whether rating agencies played a passive role or were an active driving force during Europe??s sovereign debt crisis. We address this by estimating relationships between sovereign debt ratings and macroeconomic and structural variables. We then use these equations to decompose actual ratings into systematic and arbitrary components that are not explained by previously observed procedures of rating agencies. Finally, we check whether systematic, as well as arbitrary, parts of credit ratings affect credit spreads. We find that both do affect credit spreads, which opens the possibility that arbitrary rating downgrades trigger processes of self-fulfilling prophecies that may drive even relatively healthy countries towards default.     

Sovereign Default Risk and Recovery Rates: What Government Bond Markets Expect for Greece

Bond market data on sovereign bond yields is used to estimate sovereign default risk and the amount of the expected “hair‐cut” for Greece between 2008 and 2011. Using a structural pricing model that relies on compound option theory short‐term and long‐term default probabilities and their dependencies can be inferred. Thereby bond yield spreads for different maturities are integrated. In addition, a reduced form model is applied to infer the recovery rate expected by bond market participants. The paper shows that sovereign default risk and recovery rate dynamics reflect events that are important for Greece's repayment capacity.     

The price of the euro: evidence from sovereign debt markets

The objective of this article is to ascertain how the Economic and Monetary Union (EMU) in Europe has affected its members’ long-term government bond yields. In order to estimate the effect, this article utilizes a synthetic control approach. The main finding is that the majority of the member countries did not receive economic gains from the EMU in sovereign debt markets. Synthetic counterfactual analysis finds strong evidence that Austria, Belgium, Finland, France and the Netherlands have paid a positive and substantial euro-premium in their 10-year government bonds since the adoption of the single currency. After the most recent financial crisis, government bond yields have been higher in all member countries compared to the situation that would have occurred without the monetary unification. This article concludes that from the viewpoint of sovereign borrowing, it would be beneficial for a country to maintain its own currency and monetary policy.     

Modelling sovereign credit ratings: The accuracy of models in a heterogeneous sample

The accuracy of sovereign credit ratings renewed interest toward sovereign credit ratings in the aftermath of the 2008 financial crisis. The controversy over the accuracies encouraged internal credit scoring systems to reduce reliance on sovereign credit ratings. By employing classification and regression trees (CART), multilayer perceptron (MLP), support vector machines (SVM), Bayes Net, and Naïve Bayes; we explore the prediction performance of several artificial intelligence (AI) techniques in predicting sovereign credit ratings in a heterogeneous sample. The results suggest that AI classifiers outperform the conventional statistical technique in terms of accurate prediction. According to within one notch and two notches accurate prediction measure, the prediction performances of the AI classifiers exceed 90% accuracy whereas the performance of the conventional statistical method is around 70%. The results further reveal that the prediction performance of the models declines around the threshold rating that is located between investment grade and speculative grade which is not necessarily the result of inadequacy of the models. Rather, this is potentially due to CRAs' cautious behaviour toward those countries around threshold rating which can be interpreted as the certification price of upgrading to investment grade.