Public Finance Division

Moody's - Definitions of Bond Ratings

Long-Term Obligation Ratings

Moody’s long-term ratings are opinions of the relative credit risk of financial obligations with an original maturity of one year or more. They address the possibility that a financial obligation will not be honored as promised. Such ratings use Moody’s Global Scale and reflect both the likelihood of default and any financial loss suffered in the event of default.

Aaa Obligations rated Aaa are judged to be of the highest quality, with minimal credit risk.
Aa Obligations rated Aa are judged to be of high quality and are subject to very low credit risk.
A Obligations rated A are considered upper-medium grade and are subject to low credit risk.
Baa Obligations rated Baa are subject to moderate credit risk. They are considered medium grade and as such may possess certain speculative characteristics.
Ba Obligations rated Ba are judged to have speculative elements and are subject to substantial credit risk
B Obligations rated B are considered speculative and are subject to high credit risk.
Caa Obligations rated Caa are judged to be of poor standing and are subject to very high credit risk.
Ca Obligations rated Ca are highly speculative and are likely in, or very near, default, with some prospect of recovery of principal and interest.
C Obligations rated C are the lowest rated class and are typically in default, with little prospect for recovery of principal or interest.

Since October 1996 Moody's has applied numerical modifiers 1, 2, and 3 in each generic rating classification from Aa to B. (see Moody's Expanded Public Finance Rating Symbols chart below). The modifier 1 indicates that the issue ranks in the higher end of its generic rating category, the modifier 2 indicates a mid-range ranking, and the modifier 3 indicates that the issue ranks in the lower end of its generic category.

Moody's Expanded Public Finance Rating Symbols

Previous Rating Symbol New Rating Symbol
Aaa Aaa
Aa1 Aa1
Aa Aa2
A1 A1
A A2
Baa1 Baa1
Baa Baa2
Ba1 Ba1
Ba Ba2
B1 B1
B B2
Caa Caa
Ca Ca

Short-Term Prime Rating System

Moody's employs the following three designations, all judged to be investment grade, to indicate the relative repayment ability of rated issuers:

Prime-1 Issuers rated Prime-1 (or supporting institutions) have a superior ability for repayment of senior short-term debt obligations. Prime-1 repayment ability will often be evidenced by many of the following characteristics:
  • Leading market positions in well-established industries.
  • High rates of return on funds employed.
  • Conservative capitalization structure with moderate reliance on debt and ample asset protection.
  • Broad margins in earnings coverage of fixed financial charges and high internal cash generation.
  • Well-established access to a range of financial markets and assured sources of alternate liquidity.
Prime-2 Issuers rated Prime-2 (or supporting institutions) have a strong ability for repayment of senior short-term debt obligations. This will normally be evidenced by many of the characteristics cited above but to a lesser degree. Earnings trends and coverage ratios, while sound, may be more subject to variation. Capitalization characteristics, while still appropriate, may be more affected by external conditions. Ample alternate liquidity is maintained.
Prime-3 Issuers rated Prime-3 (or supporting institutions) have an acceptable ability for repayment of senior short-term obligations. The effect of industry characteristics and market compositions may be more pronounced. Variability in earnings and profitability may result in changes in the level of debt protection measurements and may require relatively high financial leverage. Adequate alternate liquidity is maintained.
Not Prime Issuers rated Not Prime do not fall within any of the Prime rating categories.

Moody's Short-Term MIG/VMIG Ratings - US Tax-Exempt Municipals

There are four rating categories for short-term obligations that define an investment grade situation. These are designated Moody's Investment Grade as MIG 1 (best quality) through MIG 4 (adequate quality). Short-term obligations of speculative quality are designated SG.

In the case of variable rate demand obligations (VRDOs), a two-component rating is assigned. The first element represents an evaluation of the degree of risk associated with scheduled principal and interest payments, and the other represents an evaluation of the degree of risk associated with the demand feature. The short-term rating assigned to the demand feature of VRDOs is designated as VMIG. When either the long- or short-term aspect of a VRDO is not rated, that piece is designated NR, e.g., Aaa/NR or NR/VMIG 1.

Issues or the features associated with MIG or VMIG ratings are identified by date of issue, date of maturity or maturities or rating expiration date and description to distinguish each rating from other ratings. Each rating designation is unique with no implication as to any other similar issue of the same obligor. MIG ratings terminate at the retirement of the obligation while VMIG rating expiration will be a function of each issue's specific structural or credit features.

MIG 1/VMIG 1 This designation denotes best quality. There is present strong protection by established cash flows, superior liquidity support or demonstrated broad-based access to the market for refinancing.
MIG 2/VMIG 2 This designation denotes high quality. Margins of protection are ample although not so large as in the preceding group.
MIG 3/VMIG 3 This designation denotes favorable quality. All security elements are accounted for but there is lacking the undeniable strength of the preceding grades. Liquidity and cash flow protection may be narrow and market access for refinancing is likely to be less well established.
MIG 4/VMIG 4 This designation denotes adequate quality. Protection commonly regarded as required of an investment security is present and although not distinctly or predominantly speculative, there is specific risk.
SG This designation denotes speculative quality. Debt instruments in this category lack margins of protection.