A rating ascribed to bonds with relatively low risk of default. Rating agencies such as Standard & Poor’s use several designations that comprises of uppercase and lowercase letters ‘A’ and ‘B’ to denote a credit quality rating of a bond. Rates ‘AAA’ and ‘AA’ (high credit quality), as well as ‘A’ and ‘BBB’ (medium credit quality) are investment grades. Credit rating for bonds below these ratings such as ‘BB’, ‘B’, and ‘CCC’ are low credit quality and commonly called "junk bonds".