What it means
Risk is usually measured where it is created: a loan in the lending book, a receivable in the sales ledger, a currency position in treasury. Aggregate risk cuts across those boundaries and totals every exposure to the same counterparty, country, industry, weather event or supplier.
The total is frequently far larger than anyone expected. The reason this matters is that losses are correlated.
If a major customer fails, you lose the receivable, the deposit you placed with them, the value of the tooling you bought for their contract and the profit from next year's orders, all at once. Managing each item separately makes each look tolerable while the combined loss threatens the business.
Financial institutions formalise this through large exposure limits, typically expressed as a percentage of capital, and they must count on-balance-sheet lending together with undrawn facilities, guarantees, derivative exposures and settlement risk. Insurers do the same thing geographically, adding up every policy that a single storm or earthquake could touch.
Ordinary companies have the same problem in less regulated form. Concentration in one customer, one supplier, one distribution channel, one currency or one physical site is aggregate risk, and it is one of the first things an acquirer or a lender examines.
A business earning 45% of revenue from one client does not have a diversified customer base regardless of how many small accounts sit alongside it. The practical discipline is to define the risk factor first, then hunt for every exposure to it, including indirect ones.
Second-tier suppliers, shared components, and different customers who happen to serve the same end market are the exposures that get missed, and they are usually the ones that hurt.
In practice
Real-world examples.
Example
A specialist electronics assembler buys from eleven different suppliers and feels well diversified. A review shows nine of them source the same controller chip from one fabrication plant, so a single plant outage would stop 80% of production.
Example
A property insurer writes policies through four separate brokers along one stretch of coastline. Adding the exposures together shows $340,000,000 of insured value inside a single hurricane footprint, well above its reinsurance protection, and it stops writing new business in the area.
Example
An advertising agency counts twenty-two clients and considers its revenue well spread. Grouped by sector, fourteen of them are consumer travel brands, so a downturn in travel advertising would remove more than half of billings at once.
Formula
Calculation
Aggregate exposure = sum of all exposures to the common risk factor, and the headroom against a limit is limit - aggregate exposure, where the limit is often a percentage of capital.
A commercial bank reviews everything it has extended to one corporate group across four separate desks. Lending drawn is $40,000,000, undrawn but committed revolving facilities are $15,000,000, the positive mark-to-market on foreign exchange derivatives is $6,000,000, and trade finance guarantees are $9,000,000.
Aggregate exposure is $40,000,000 + $15,000,000 + $6,000,000 + $9,000,000 = $70,000,000. The bank's internal single-counterparty limit is 25% of Tier 1 capital, and Tier 1 capital is $240,000,000, so the limit is 0.25 x $240,000,000 = $60,000,000.
The group is therefore over limit by $70,000,000 - $60,000,000 = $10,000,000, or $10,000,000 / $60,000,000 = 16.7% above the ceiling. No individual desk had breached anything, because the largest single exposure was $40,000,000 against a $60,000,000 limit, which is precisely how aggregate risk builds up unnoticed.Case study
Seen in the real world.
Pellworth Components is an illustrative, fictional supplier of precision parts to the automotive sector with revenue of about $86,000,000. Its board reviewed customer concentration each quarter and was comfortable that no single customer exceeded 18% of sales.
A new finance director asked a different question: not who pays us, but what ultimately drives the payment. Mapping the order book to end vehicles showed that four separate customers, together worth $37,000,000 of revenue, all fed components into the same electric van platform. On top of that, Pellworth held $4,200,000 of platform-specific tooling and $2,900,000 of dedicated inventory.
Aggregate exposure to that one platform was therefore $37,000,000 + $4,200,000 + $2,900,000 = $44,100,000, which is $44,100,000 / $86,000,000 = 51.3% of annual revenue tied to a single vehicle programme. In this fictional case the board set a concentration ceiling of 35%, funded a sales push into two other platforms, and negotiated tooling cost recovery clauses into the next contract round.
Watch out
Common mistakes.
- Measuring exposures only where they are recorded. Aggregate risk lives across systems and departments, so a total that comes from one ledger is almost always understated.
- Counting only direct relationships. Shared sub-suppliers, common end markets and correlated geographies create exposure that never appears on a customer or supplier list.
- Assuming a large number of counterparties means low concentration. Twenty customers in one industry behave like one customer when that industry turns.
Questions
People also ask.
How is aggregate risk different from a single large exposure?
A single large exposure is visible in one place, while aggregate risk is the sum of many smaller exposures to the same underlying driver.
What is a sensible concentration limit for a company?
There is no universal figure, but many boards become uncomfortable above 20% to 25% of revenue or gross profit from one customer, sector or site.
How often should aggregate exposures be reviewed?
At least quarterly for most businesses, and immediately after any acquisition, major contract win or change in supplier base, because those events reshape the picture fastest.
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