AAA Highest quality. Ability to pay interest and principal very strong.
AA High quality. Ability to pay interest and principal strong.
A Medium to high quality. Ability to pay interst and principal, but more susceptible to changes in circumstances and the economy.
BBB Medium quality. Adequate ability to pay, but highly susceptible to adverse circumstances.
BB Speculative. Less near-term likelihood of default relative to other speculative issues.
B Current capacity to pay interest and principal, but highly susceptible to changes in circumstances.
CCC Likely to default, where payment of interest and principal is dependent on favorable circumstances.
CC Debt subordinate to senior debt rated CCC
C Debt subordinate to senior debt rated CCC-
D Currently in default, where interest or principal has not been made as promised.
Source: Standard & Poor's CREDITWEEK, "Long-term Rating Definitions," February 11, 1991, p. 128.
Es gibt noch andere credit rating Agenturen. 100% Sicherheit gibt's natuerlich nicht.