Aaa – bonds of highest quality Aa – bonds of high quality A – bonds whose security of principal and interest is considered adequate but may be impaired in the future Baa – bonds of medium grade that are neither highly protected nor poorly secured Ba – bonds of speculative quality whose future cannot be considered well assured B – bonds that lack characteristics of a desirable investment Caa – bonds in poor standing that may be defaulted Ca – speculative bonds that are often in default C – bonds with little probability of any investment value (lowest rating)