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Aaa
Obligations rated Aaa are judged to be of the highest quality, with minimal credit risk.
Aa1, Aa2, Aa3
Obligations rated Aa are judged to be of high quality and are subject to very low credit risk.
A1, A2, A3
Obligations rated A are considered upper-medium grade and are subject to low credit risk.
Baa1, Baa2, Baa3
Obligations rated Baa are subject to moderate credit risk. They are considered medium-grade and as such may possess certain speculative characteristics.