What it means
The phrase is a description of concentration rather than any formal designation. Whoever uses it is telling you that three firms set the terms in a market, so the first thing to establish is which market they are describing.
In finance the credit rating meaning comes up most often. Those three agencies assign the letter grades that drive the interest rate an issuer pays and determine which bonds many pension funds and insurers are permitted to buy at all.
In manufacturing the phrase points to General Motors, Ford and the business that grew out of Chrysler, now part of a larger European-American group. It turns up in discussions of cyclical demand, union negotiations, legacy pension obligations and the supplier networks that depend on their production volumes.
In asset management it means the three firms that run the largest index funds. They matter in corporate governance because index funds hold shares in almost every large company and vote them, so questions about executive pay and board composition increasingly get aimed at those three stewardship teams.
Other industries borrow the label freely, from the three largest audit-adjacent consultancies to the three biggest players in a national supermarket or telecoms market. The common thread is that three firms are large enough to make price leadership possible without any formal agreement between them.
The practical habit is to pin the phrase down and then measure it. Ask big three of what, then calculate the three-firm concentration ratio so the claim of dominance is backed by a number rather than a feeling.
A number also lets you track whether concentration is rising or easing over time.
In practice
Real-world examples.
Example
A property group preparing its first bond issue seeks ratings from two of the three agencies. The second rating costs around $150,000 but widens the pool of buyers, because many investment mandates require two ratings before a bond is eligible. The treasurer treats the extra fee as the price of a lower coupon.
Example
A components supplier with 80% of its sales going to the three large US vehicle makers presents to its bank. The bank treats the concentration as the main credit risk rather than the balance sheet itself. It asks for monthly order book reporting and a covenant on customer diversification as conditions of the facility.
Example
A head of investor relations prepares for proxy season and books meetings with the stewardship teams of the three largest index managers. Together they control enough of the register to decide a close vote on a new share incentive plan.
Formula
Calculation
Three-firm concentration ratio, written CR3 = combined revenue of the three largest firms / total revenue of the market, expressed as a percentage.
Suppose a market generates $50,000,000,000 of annual revenue, and the three largest firms earn $14,000,000,000, $12,000,000,000 and $9,000,000,000. Their combined revenue is $14,000,000,000 + $12,000,000,000 + $9,000,000,000 = $35,000,000,000.
CR3 is therefore $35,000,000,000 / $50,000,000,000 = 0.70, or 70%. Competition authorities generally treat a CR3 above about 70% as a highly concentrated market, which is the point at which pricing power and barriers to entry deserve a close look.Case study
Seen in the real world.
Northgate Brake Systems is a fictional supplier created for this illustrative example. Roughly 76% of its $220,000,000 revenue comes from three vehicle manufacturers, and the illustrative board has treated that as a strength because the contracts are long and the volumes are predictable.
When one of the three cuts production of a single model, the fictional company loses $31,000,000 of annual revenue at a stroke and cannot reduce its fixed factory costs anywhere near as quickly. Its lenders tighten terms, and the ratings on its private placement notes are reviewed.
The illustrative board response is a five-year plan to bring customer concentration below 50% by selling into agricultural and industrial equipment. The point of the fictional story is that dealing with a market's dominant three is good business until it becomes the only business.
Watch out
Common mistakes.
- Using the phrase without saying big three of what, which leaves the reader guessing between rating agencies, vehicle makers and fund managers.
- Assuming a credit rating is a recommendation to buy, when it is an opinion on the likelihood of repayment and nothing more.
- Treating heavy sales concentration on three large customers as pure strength, without modelling what happens when one of them cuts volumes.
Questions
People also ask.
Who are the Big Three credit rating agencies?
S&P Global Ratings, Moody's and Fitch Ratings, which between them produce the great majority of ratings used in bond markets.
Why does customer concentration worry lenders?
Because losing one large customer can wipe out a disproportionate share of revenue while fixed costs stay in place.
How concentrated is too concentrated?
There is no single threshold, although a three-firm concentration ratio above roughly 70% is normally described as a highly concentrated market.
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