由于在信贷危机前过分的夸大了抵押保证债券的优点，评级机构的声誉依然背负着不良影响。

The reputations of the ratings agencies are still stained by their gross overstating of the quality of mortgage-backed bonds before the credit crisis (see article).

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评级机构正改变立场，下调了许多抵押债券的等级，并保证密切关注债务抵押债券。

The agencies have been shifting their ground, downgrading mortgage-backed bonds by the dozen and promising to keep a close eye on CDOs.

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其二，美联储已经在交易低风险，低回报的国债和购买高收益的私人债券-例如银行贴现贷款，商业票据，和抵押担保证券。

Second, it has been trading in low-risk, low-return Treasury debt and buying higher-yielding private debt—discount loans to banks, commercial paper, and mortgage-backed securities, for example.

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