????幾位教授還分析了不同種類資產(chǎn)的評級升降幾率，發(fā)現(xiàn)了類似的規(guī)律,。五年后,，27%的原定為A級的公司債券遭到降級，而市政債券和主權(quán)債券中這一比例分別只有6%和3%,，結(jié)構(gòu)型產(chǎn)品不出所料仍是表現(xiàn)最差的,，降級率高達(dá)53%。

????穆迪對該研究嗤之以鼻,?！拔覀儾徽J(rèn)同該調(diào)查的方法和結(jié)論，”穆迪發(fā)言人邁克爾?阿德勒稱,，“它試圖得出關(guān)于穆迪評級的長期表現(xiàn)和可比性的過于寬泛的結(jié)論,，但過于依賴金融危機(jī)造成的評級波動，而在危機(jī)期間穆迪的評級變動正反映了與美國房地產(chǎn)有關(guān)的證券的信用史無前例的下降,?！?/p>

????結(jié)果性產(chǎn)品在危機(jī)期間的表現(xiàn)極差，但評級機(jī)構(gòu)辯護(hù)稱,，這些證券當(dāng)初得分很高是因?yàn)樗鼈儾粔蛲该?，難以評估。研究報(bào)告的執(zhí)筆者針鋒相對地指出,，如果這種不透明性辯護(hù)真的成立,，那抵押貸款或信用卡應(yīng)收賬款之類的簡單工具，就沒有理由比包含資產(chǎn)負(fù)債表外負(fù)債和合成租賃的復(fù)雜公司債券更寬大的評級?？墒聦?shí)是,，結(jié)果性產(chǎn)品獲得的評級通常都更寬大，無論復(fù)雜與否,。

????這幾位教授得出結(jié)論是：評級注水程度與不透明性無關(guān),，倒是與收入有關(guān)?！敖Y(jié)構(gòu)性金融產(chǎn)品帶來的收入遠(yuǎn)比金融債券的貢獻(xiàn)大,，而公司債券相比主權(quán)債券和市政債券，貢獻(xiàn)的收入又多了不少,，”他們寫道,。

????三大評級機(jī)構(gòu)的商業(yè)模式本就飽受批評——債券發(fā)行者付錢獲得評級，有利益沖突之嫌,，本研究再度凸顯了這一問題,。盡管幾位教授并未直接指控評級機(jī)構(gòu)根據(jù)收錢多少決定評級，但其言下之意再清晰不過：財(cái)大氣粗的發(fā)行者獲得的評級更寬松,。

????關(guān)于市政債券是否終于獲得了公允評級,，科爾納賈稱，現(xiàn)在判斷還為時(shí)過早,。但他指出,，評級機(jī)構(gòu)的商業(yè)模式并未改變，因此促使這些機(jī)構(gòu)給予付費(fèi)更高的客戶更高評級的動力也仍然存在,。

????評級機(jī)構(gòu)的這種行為對養(yǎng)老金和保險(xiǎn)公司等機(jī)構(gòu)投資者的影響最大,，因?yàn)樗鼈兺ǔＪ艿较拗疲荒苜徺I高評級債券,。由于這些投資者可以挑選多種類型資產(chǎn),，他們有理由買入收益率更高的債券——而他們可能不知道這些債券的評級有注水之嫌?？茽柤{賈指出,，這造成為政府債券承擔(dān)利息的納稅人利益受損。

????作為《多德-弗蘭克法案》(Dodd-Frank Act)的一部分,，美國證券交易委員會（SEC）正在調(diào)查多個(gè)與評級機(jī)構(gòu)有關(guān)的事項(xiàng),，其中之一就是標(biāo)準(zhǔn)化問題。SEC已經(jīng)要求評級機(jī)構(gòu)就多個(gè)問題作出解釋,，其中就包括“不同種類資產(chǎn)的評級是否可以比較”,。

????穆迪常務(wù)董事法里薩?扎林書面回應(yīng)稱，該機(jī)構(gòu)的評級可用于“比較不同國家和地區(qū),、產(chǎn)業(yè)及資產(chǎn)種類的風(fēng)險(xiǎn),，從而促進(jìn)全球范圍內(nèi)資產(chǎn)的高效流動,。”

????科爾納賈指出,，他的研究駁斥了該機(jī)構(gòu)的說法,，表明其評級并不統(tǒng)一。他說：“我們揭示了他們所言不實(shí),。”

????The professors also analyzed the rate at which different types of assets had their ratings downgraded or upgraded and found a similar pattern. After five years, 27% of A-rated corporate bonds were downgraded, versus 6% of municipal bonds and just 3% of sovereign issues. Unsurprisingly, a whopping 53% of CDOs were downgraded.

????Moody's dismisses the research. "We disagree with the study's methods and findings," says Michael Adler, a spokesperson for Moody's. "It attempts to draw broad conclusions about the performance and comparability of Moody's ratings over time by relying disproportionately on ratings volatility stemming from the financial crisis, a period in which Moody's' ratings changes reflected the unprecedented decline in credit quality for U.S. housing related securities."

????When structured products tanked during the crisis, ratings agencies defended the securities' high scores by arguing that they were too opaque to evaluate. The study's authors reject that idea. If the opacity defense were true, they wrote, then simple pools of mortgages or credit card receivables ought to have received less inflated ratings than complex corporate issuers with off-balance sheet debt and synthetic leases. But structured products routinely received more liberal grades, irrespective of their complexity.

????The professors concluded that ratings inflation corresponded not to opacity, but revenue. "Revenues generated from structured finance products are significantly higher than those generated from corporate issuers, which are, in turn, higher than those generated from sovereign issuers and municipalities," they wrote.

????The findings corroborate the theory that the agencies' much-critiqued business model, in which bond sellers pay for their own ratings, poses a conflict of interest. Though the professors don't outright accuse the ratings agencies of running a pay-for-play scheme, the implications are clear: Issuers with bigger pockets received more generous scores.

????Cornaggia says it's too soon to tell if municipal bonds are finally receiving a fair shake. But he points out that the industry's business model is the same. As a result, he says, the impetus that may have induced agencies to plump ratings for higher-paying customers hasn't gone away.

????Such practices impact institutional buyers like pensions and insurers, which are often restricted to buying highly rated debt. Because these investors can shop across assets, they have an incentive to buy bonds with fatter yields--even if, unbeknownst to them, those bonds' ratings were inflated. As a result, Cornaggia says, taxpayers, who pay out interest rates on public bonds, suffered.

????As part of the Dodd-Frank Act, the SEC is looking at a number of topics related to the ratings agencies, one of which is standardization. The SEC posted a request for comments that asked, amongst other things, whether ratings were "comparable across asset classes."

????Farisa Zarin, a managing director at Moody's, wrote in response that the agency's ratings are used "to compare risk across jurisdictions, industries and asset classes, thereby facilitating the efficient flow of capital worldwide."

????Cornaggia says his study refutes the agency's claim that its ratings are universal. "What we've shown is that's not the case," he says.