What it means
Lenders and investors need to know how risky a borrower is, and few of them can analyse every borrower themselves. Rating agencies do the analysis once and publish a grade that everyone can use.
The grade compresses a detailed assessment of the borrower's business, finances, structure and prospects into a single symbol that maps to a historical probability of default, from very rare for AAA borrowers to frequent for those rated CCC. For a corporate borrower, the agency's analysts review the financial statements, forecasts, industry position, competitive dynamics, management strategy, capital structure, liquidity and financial policy, and for specific instruments the terms, security and ranking of the debt, with management meeting the analysts and providing non-public information under confidentiality.
A rating committee then decides the grade, which is published with a report explaining the rationale, the factors that could lead to an upgrade or downgrade, and an outlook (positive, stable, negative) for the next year or two. Ratings are reviewed at least annually and whenever events warrant, and a rating may be placed on watch pending a specific development such as an acquisition.
The consequences are direct. The interest rate a borrower pays in the bond market is the risk-free rate plus a spread that widens as the rating falls: in normal markets, a few tenths of a percent for AA, one to two percent for BBB and four to eight percent for B.
Access to markets also depends on the grade, since the commercial paper market is open only to top-tier short-term ratings and many institutional investors may hold only investment-grade debt, so a downgrade from BBB- to BB+ (a "falling angel") forces selling and sharply raises the borrower's cost. Contracts reference ratings: a downgrade can trigger collateral calls under derivative agreements, step-ups in loan margins, termination rights in supply contracts and requirements to post cash under leases.
Companies therefore manage to a target rating, adjusting leverage, dividends and acquisitions to protect it. The agencies' published thresholds (leverage and coverage ratios by rating band and sector) effectively become the company's financial policy.
Ratings have well-known limitations: they lag, because agencies move after the evidence and bond prices often signal deterioration first. They are paid for by the issuer, which creates an incentive that agencies manage through separation of analysts from commercial staff and that critics regard as inherently compromised, and they failed spectacularly on structured products before the financial crisis, when securities built from sub-prime mortgages carried AAA ratings the models did not justify.
They are also opinions about probability, not guarantees: investment-grade companies do default, and the rating's value is statistical across a portfolio, not a promise about any one borrower. Internal ratings serve the same function inside banks and companies.
A bank grades every borrower on a scale mapped to probability of default and loss given default, which drives pricing, provisioning, capital and approval authority, and a company's credit control function grades customers to set limits and terms. Trade credit agencies provide scores for small companies that have no public rating, and the principles are those of credit analysis: the rating is the analysis summarised for use.
In practice
Real-world examples
Example 1
A utility maintains an A rating by keeping debt / EBITDA below 2.5 and communicates that policy to investors, who price its bonds 0.4% over the benchmark.
Example 2
A retailer is downgraded from BBB- to BB+ after two years of falling profits, its bonds fall 8 points as investment-grade funds sell, and its next refinancing costs 2.5% more.
Example 3
A private company obtains a rating for the first time to issue bonds, and the process of preparing for it (financial policy, disclosure, governance) changes how its board thinks about leverage.
Think of it
A credit rating is like a report card for borrowers. Better grades mean better loan terms; poor grades mean higher rates or no loan at all.
Formula
Calculation
A credit rating is a judgement, not a calculation, but agencies publish the financial thresholds that inform it, and borrowers manage to them.
Typical corporate thresholds (illustrative, vary by sector and agency):
- AA: Debt / EBITDA below 1.5; FFO / Debt above 45%; EBITDA / Interest above 12
- A: Debt / EBITDA 1.5 to 2.5; FFO / Debt 30% to 45%; Interest cover 8 to 12
- BBB: Debt / EBITDA 2.5 to 3.5; FFO / Debt 20% to 30%; Interest cover 4 to 8
- BB: Debt / EBITDA 3.5 to 4.5; FFO / Debt 12% to 20%; Interest cover 2.5 to 4
- B: Debt / EBITDA above 4.5; FFO / Debt below 12%; Interest cover below 2.5
Cost of a downgrade = Increase in spread x Debt to be refinanced + Effect of rating triggers + Loss of market access
Rating headroom = Distance between current ratios and the thresholds for the next lower rating
Worked example. A listed packaging company rated BBB (stable outlook) has debt of $900,000,000, EBITDA of $300,000,000, funds from operations (FFO) of $220,000,000 and interest of $45,000,000. Ratios: debt / EBITDA 3.0; FFO / debt 24%; interest cover 6.7. All are within the BBB band, with headroom: EBITDA could fall to about $257,000,000 (14%) before debt / EBITDA exceeded 3.5.
Proposed acquisition: $500,000,000, debt-funded, adding $120,000,000 of EBITDA and $90,000,000 of FFO. Pro forma: debt $1,400,000,000; EBITDA $420,000,000; FFO $310,000,000; interest $75,000,000. Ratios: debt / EBITDA 3.3; FFO / debt 22%; interest cover 5.6. The company is still BBB but at the edge, because debt / EBITDA sustained above 3.5 would prompt a downgrade to BB+, and integration risk plus a modest EBITDA shortfall could take it there.
Cost of a downgrade to BB+: the bond spread would widen from about 1.6% to about 3.2% over the benchmark. On $1,400,000,000 of debt refinanced over the following five years, the incremental cost is about $22,000,000 a year at full effect. The $200,000,000 commercial paper programme would close, requiring costlier bank funding. Two supply contracts with rating triggers would let customers demand letters of credit ($30,000,000 of facilities), and the largest bond investors, restricted to investment grade, would sell.
Decision: the board funds $150,000,000 of the acquisition with equity, taking pro forma debt to $1,250,000,000, debt / EBITDA to 3.0 and FFO / debt to 25%. It suspends the buyback programme for two years and commits publicly to debt / EBITDA below 3.0 through the cycle, and the agency affirms BBB with a stable outlook. The equity issue dilutes shareholders, but the board judges that cheaper than a recurring $22,000,000 a year of extra interest plus the trigger costs and loss of market access.
Internal rating example: a bank's internal scale maps the company at grade 5 of 10 (BBB equivalent), with a probability of default of 0.3% a year and a loss given default of 40% on unsecured exposure. Its expected loss on a $50,000,000 unsecured facility is $50,000,000 x 0.3% x 40% = $60,000 a year, and its capital requirement and pricing follow from the grade.Case study
Seen in the real world
This is a fictional, illustrative scenario. A listed engineering group had been rated A for a decade and prized the rating. Its chief executive proposed a transformational acquisition that would double the group's size, funded 80% by debt, and the board approved it on the strength of the strategic logic and the chief executive's assurance that the rating would be "protected by synergies". The agency placed the group on watch negative on announcement and downgraded it two notches to BBB- on completion, citing leverage of 4.2 times EBITDA and integration risk; a second agency went to BB+.
The consequences arrived in sequence: the group's commercial paper programme closed and it drew $600,000,000 of bank lines at a higher cost; its bonds fell 12 points; three derivative counterparties called for collateral under rating triggers, requiring $180,000,000 of cash; its main customer, whose supply contract had a rating clause, demanded a bank guarantee; and the synergies took two years longer than planned. The group sold two divisions at a discount to restore its balance sheet, and its rating returned to BBB after four years. The chairman's letter conceded that the board had treated the rating as a consequence of the deal rather than as a constraint on it, and the group's new financial policy set a rating floor of BBB+ with the leverage limits to maintain it, to be tested before any transaction was approved.
Watch out
Common mistakes
- Treating a rating as a guarantee of repayment. It is a statistical opinion about probability; investment-grade borrowers default, rarely, and speculative-grade ones frequently.
- Ignoring rating triggers in contracts and derivatives, which can turn a downgrade into a liquidity crisis through collateral calls and termination rights.
- Approving a transaction without testing its effect on the rating and pricing the cost of a downgrade, which can exceed the transaction's benefit.
Questions
People also ask
What is the difference between investment grade and speculative grade?
Investment grade (BBB- and above) indicates adequate to very strong capacity to meet obligations; speculative grade (BB+ and below) indicates significant uncertainty. Many investors and regulations restrict holdings to investment grade, so the boundary has large consequences for cost and access.
Who pays for a credit rating?
Usually the issuer, which creates a conflict of interest that agencies manage through internal separation and that regulators supervise. Some ratings are unsolicited, and investors also subscribe to agency research.
How does a company improve its rating?
By reducing leverage, improving coverage and cash flow, diversifying its business, adopting and demonstrating a conservative financial policy, and maintaining liquidity. Ratings respond to sustained evidence rather than to single years.