Even so, Anadarko bond investors, fearing rating agency downgrades, have sold the paper in recent days.

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Similar downgrades of the other bond insurers are likely.

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These fears spill over into the bond markets, as this week's downgrades by Moody's, a ratings agency, have underlined.

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The prospect of downgrades have also wracked the companies' stocks because a bond insurer without the highest-quality rating would have trouble winning new business.

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The only emerging market nations to see downgrades or credit outlook changes to negative were in the junk bond space, and some corporates.

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