Who are the rating services and what are their bond ratings? Based on the ratings, what are the differences between investment grade bonds and junk bonds? What do the ratings mean and how important are the ratings when buying a bond? When would buy an investment grade bond? When would you buy a junk bond?
Rating services could be private independent rating such as Standard & Poor's, Moody's and Fitch provide these grades:
AAA and AA: High credit-quality investment grade
AA and BBB: Medium credit-quality investment grade
BB, B, CCC, CC, C: Low credit-quality (non-investment grade), or "junk ...
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