AAA bonds of highest quality. AA high-quality debt obligations. A Bonds that have a strong capacity to pay interest and principal but may be susceptible to adverse effects. BBB bonds that have an adequate capacity to pay interest and principal, but are more vulnerable to adverse economic conditions or changing circumstances. BB, B, CCC primary speculative bonds with great uncertainties and major risk if exposed to adverse conditions. C income bonds on which no interest is being paid. D bond is in default.