Credit Rating Agencies Explained

Three firms — S&P Global Ratings, Moody's, and Fitch Ratings — assess the creditworthiness of most of the world's governments and large corporate borrowers, and their opinions move bond prices, set borrowing costs, and in many cases determine which investors are even legally permitted to buy a given bond. Understanding how these credit rating agencies (CRAs) actually operate, who pays them, and why their role has been so heavily criticised is essential context for anyone working with fixed income or corporate finance.

Who the Major Credit Rating Agencies Are

The "Big Three" — S&P, Moody's, and Fitch — dominate global credit ratings, together holding the large majority of the market for rated debt worldwide. A number of smaller agencies operate alongside them, some with strong regional presence (such as agencies focused on Chinese or Japanese domestic markets), but the Big Three's ratings remain the reference point most investors, regulators, and index providers use. For a primer on what a credit rating itself actually measures, see our guide to what credit ratings are.

The Issuer-Pays Business Model

Almost uniquely among gatekeeper institutions, the major CRAs are paid by the entities they rate, not by the investors who rely on those ratings. An issuer wanting to sell a bond typically pays one or more agencies a fee to assign and maintain a rating, because institutional investors, pension funds, and regulatory capital rules often require or strongly prefer rated debt. This "issuer-pays" model replaced an older "subscriber-pays" structure decades ago, largely because ratings could be freely copied and shared once published, undermining the economics of charging investors directly.

The obvious structural concern with issuer-pays is the potential conflict of interest: an agency competing for an issuer's repeat business has some incentive to be accommodating on methodology or rating outcome, particularly for complex structured products where the issuer can shop between agencies for the most favourable opinion. This dynamic was widely cited as a contributing factor in the 2008 financial crisis, when large volumes of mortgage-backed securities carried top-tier ratings that proved far too optimistic once the underlying loans began defaulting.

How Ratings Are Assigned

Each agency maintains its own rating methodology, generally combining quantitative financial analysis (leverage, cash flow coverage, liquidity, profitability trends) with qualitative judgment (management quality, competitive position, industry outlook, and for sovereigns, political stability and institutional strength). A rating committee, rather than a single analyst, typically makes the final determination, and the process includes ongoing surveillance after the initial rating is assigned, with periodic reviews and the possibility of upgrades, downgrades, or a change in outlook (positive, negative, or stable) between full reviews.

Rating scales differ slightly between agencies but follow a broadly similar structure, running from the highest investment-grade tiers (AAA/Aaa) down through progressively lower investment-grade and then speculative-grade (high-yield or "junk") categories, with default ratings at the bottom. The investment-grade versus speculative-grade boundary matters enormously in practice, since many institutional mandates and regulatory capital rules treat it as a hard cutoff for what can be held or how much capital must be set aside against it.

Regulation Since the Financial Crisis

The 2008 crisis triggered a significant regulatory response aimed directly at CRAs. In the EU, the Credit Rating Agencies Regulation introduced registration and supervision requirements, rules on rotation and disclosure, and restrictions designed to reduce conflicts of interest. In the US, the Dodd-Frank Act removed many statutory references that had effectively hard-wired CRA ratings into regulatory capital requirements, and gave the SEC expanded oversight authority over nationally recognised statistical rating organisations. These reforms reduced, but did not eliminate, criticism that the issuer-pays model still embeds a structural conflict of interest into the heart of the fixed income market.

Sovereign Ratings Are a Special Case

Rating a government carries unique challenges that don't apply to corporate issuers. There's no bankruptcy process for a sovereign the way there is for a company, so agencies instead assess a government's willingness and ability to pay — a function of its fiscal position, debt trajectory, access to its own currency and central bank, political stability, and external vulnerabilities such as foreign currency reserves and current account balances. Sovereign downgrades can be politically sensitive and are closely watched by markets, since a downgrade below investment grade can trigger forced selling by funds with mandates restricting them to investment-grade sovereign debt, sometimes creating the kind of self-reinforcing market pressure that a lower rating was meant to merely reflect rather than cause.

FAQ

Why do governments and companies pay for their own credit rating?
Institutional investors and regulatory capital rules often require or strongly favour rated debt, so issuers pay for a rating to access the broadest possible pool of investors and typically achieve a lower cost of borrowing than an unrated issue would command.

Can a bond have different ratings from different agencies?
Yes — "split ratings," where agencies disagree on the appropriate rating, are common, particularly for complex credits, and investors often use the lower of the available ratings as a conservative benchmark.

Are credit ratings opinions or guarantees?
They are opinions about relative creditworthiness, not guarantees of repayment, and rating agency disclaimers explicitly state ratings should not be relied upon as the sole basis for an investment decision.

Understanding how credit risk is assessed and regulated is core to Learnsignal's ACCA and CPD course content for finance professionals working in fixed income and corporate finance.