When One Customer Is Most of the Business | HL Hunt
When One Customer Is Most of the Business
Customer concentration gets discussed as a feeling rather than a figure, and the figure most people reach for is the wrong one. A customer at 45% of revenue can easily be 157% of profit, because fixed costs do not leave when the customer does. Here is the arithmetic of what a departure actually costs, the cash needed to bridge it, how lenders quietly discount concentrated revenue, and why the cheapest fix is the one that shrinks the size of the loss rather than its probability.
What you'll learn
Start with the number
Concentration is usually discussed as a feeling: you know one customer matters a lot. Turn it into a figure and the conversation changes, because the figure that matters is not the share of revenue but the share of profit.
Take a business with $840,000 in annual revenue, a contribution margin of 35%, and fixed costs of $210,000. Its largest customer accounts for $378,000, or 45% of revenue.
- Total contribution: $840,000 × 35% = $294,000
- Profit: $294,000 − $210,000 = $84,000
- Contribution from the largest customer: $378,000 × 35% = $132,300
That customer contributes $132,300 against a business that earns $84,000. The largest customer is not 45% of the business. It is 157% of the profit.
Which produces the figure that should be written on a wall:
Per our margin analysis, if you do not know your contribution margin, that is the first figure to establish, because every calculation here depends on it. Run the same calculation for your own top three customers before reading further. The share-of-revenue number is comforting and close to meaningless. The share-of-contribution-against-fixed-costs number is the one that tells you what a departure does.
The cash a departure actually costs
The profit swing is the headline. The cash requirement is what closes businesses.
After the loss, the business runs at −$4,025 a month. If the sales cycle to replace that revenue is seven months from first conversation to first invoice paid, and replacement is not instant or certain, the cash needed to survive the gap is:
- $4,025 × 7 = $28,175, before any cost of winning the replacement business
That is the real number to hold against a concentration risk, and it is the number that determines whether a facility should be arranged now rather than later. Per our facility analysis, a line of credit arranged while the large customer is still paying is available on ordinary terms. The same line applied for after they leave is a different conversation entirely, because the financials being reviewed will show the loss.
The timing trap
Concentration risk is most financeable at the moment it is least urgent. A lender looking at a healthy business with one large customer will lend against it, with conditions. A lender looking at the same business three months after that customer left sees a revenue decline, a loss, and a request for working capital to cover it. Arrange the facility while the concentration is still a risk rather than an event.
How a lender sees it
Concentration changes underwriting in ways that are rarely stated to the borrower.
| What the lender does | Effect on the file |
|---|---|
| Discounts concentrated revenue | Only the $462,000 from other customers may be treated as reliable, which is 55% of stated revenue |
| Looks through to the customer's credit | Your risk becomes partly their risk, per our exposure analysis |
| Asks for the contract | Term, notice period, and termination rights are read closely |
| Prices the volatility | A concentrated book is a higher variance book at the same average |
| Sets a covenant | Often a requirement to report if the customer relationship changes materially |
The first row is the one worth planning around. If a lender advances against 55% of your revenue rather than 100%, the capacity available to you is roughly half what the top line suggests, and no amount of explanation changes it. Reducing concentration is therefore not only a risk measure, it is a financing capacity measure.
What concentration does to negotiation
The commercial cost shows up long before any departure, in every conversation about price and terms.
Suppose the large customer asks for a 5% price reduction. On $378,000, that is $18,900, and because the cost base does not move, it comes entirely out of profit:
- Profit before: $84,000
- Profit after a 5% concession: $65,100, a 22.5% reduction
A 5% price concession to a 45% customer costs 22.5% of the year's profit. And the reason it is hard to refuse is precisely the arithmetic in the first section: refusing risks a customer whose departure produces a $48,300 loss. Concentration converts every negotiation into one you cannot afford to lose.
The same asymmetry appears in payment terms. A request to move from 30 days to 60 is difficult to decline for the same reason, and per our timing analysis it lands directly on working capital. Per our large customer analysis, when a concentrated customer pays late, the leverage to chase is close to zero.
Useful thresholds
There is no correct level of concentration, only levels that require different responses.
| Largest customer share | What it means operationally |
|---|---|
| Under 10% | A departure is a bad quarter, not an event |
| 10% to 20% | Manageable; worth a named replacement plan |
| 20% to 35% | A departure removes most of the profit; a facility should exist |
| Over 35% | The business is effectively a supplier to one buyer and should be run as one |
| Over 50% | Treat the relationship as the business, and the rest as diversification in progress |
The bottom two rows are not failures. Plenty of good businesses are built on one or two large accounts, and pretending otherwise leads to a worse decision than accepting it and managing accordingly. What makes the position dangerous is running a 45%-concentration business with the cash buffer, the facility, and the sales pipeline appropriate to a 10% one.
Reducing it without losing the customer
The instinct is to go find more customers, which is correct and slow. Faster measures exist.
- Lengthen the notice period rather than the term. A customer reluctant to commit to two years may readily agree to 90 days' notice, which converts a cliff into a runway and costs them almost nothing.
- Diversify inside the account. Multiple departments, multiple contacts, multiple products. A relationship held by one champion ends when that person changes jobs, which per our dependency analysis is the same single-point-of-failure logic that applies on the supply side.
- Reduce fixed costs relative to the exposure. The $48,300 loss exists because $210,000 of cost does not move. Variable-cost delivery for concentrated work shrinks the swing directly.
- Price the concentration. Large-volume discounts are normal. A discount that leaves you unable to survive their departure is not a discount, it is a subsidy financed by risk.
- Build the facility now. Per our facility analysis, an unused line is cheap and an unavailable one is fatal.
- Keep the replacement pipeline warm. Seven months of sales cycle means the pipeline must exist before the call, not after it.
- Strengthen the credit side. Per our business credit analysis, a business with an established credit profile has options when revenue drops; one whose only credit history is the owner's personal file has very few.
Item three is the most underused, because it is the only one that reduces the size of the loss rather than the probability of it. Shifting concentrated delivery work from salaried staff to contracted capacity costs margin in good months and cuts the downside in the bad one.
Concentration is a financing problem before it is a sales problem
A business whose credit stands on its own can arrange capacity while the large customer is still paying. HL Hunt Business Credit Builder establishes business tradelines reported in your entity's name, so the file a lender reviews is the business's own record rather than the owner's.
The one-page concentration plan
- Calculate contribution, not revenue, for your top three customers, and compare each to annual fixed costs.
- Write down the monthly loss that each departure would produce.
- Multiply by your real sales cycle to get the bridge requirement.
- Check whether that cash exists as reserve, facility, or neither.
- Read the contract for notice period and termination rights, per our contract terms analysis approach of reading the exit before the entry.
- Identify the single point of failure in the relationship, usually one person, and add a second.
- Set a concentration target and a date, because a target without a date is an intention.
- Review quarterly, since concentration rises silently whenever the large account grows faster than the rest, and per our year-end analysis the annual close is the natural moment to record it.
Point eight catches the most common version of this problem. Nobody decides to become concentrated. It happens because the biggest customer is also the easiest to sell more to, and each individual expansion is a good decision that makes the portfolio worse.
Frequently asked questions
There is no correct level, only levels needing different responses. Above about 35% the business is effectively a supplier to one buyer. The danger is a 45% concentration run with a 10% buffer.
Because fixed costs stay when the customer leaves. A customer at 45% of revenue contributed $132,300 against $84,000 of profit, so their departure turned $84,000 of profit into a $48,300 loss.
Monthly loss times your real replacement cycle. At negative $4,025 a month and seven months to replace, about $28,175 before the cost of winning the new work.
Because you cannot afford to walk away. A 5% concession to a 45% customer cost 22.5% of annual profit, and refusing risked a departure costing far more.
Key takeaways
- Measure concentration in contribution against fixed costs, not as a share of revenue.
- In the worked case a customer at 45% of revenue produced 157% of profit, and losing them turned $84,000 of profit into a $48,300 loss.
- The bridge requirement is the monthly loss times the real replacement cycle: $4,025 a month over seven months is about $28,175.
- Arrange a facility while the large customer is still paying, because the same application after the loss is a different file.
- Lenders may treat only the non-concentrated revenue as reliable, which halves financing capacity at a 45% concentration.
- A 5% price concession to a 45% customer cost 22.5% of annual profit, and concentration is why it is hard to refuse.
- Reducing fixed costs behind concentrated work is the only measure that shrinks the size of the loss rather than its probability.
- Nobody decides to become concentrated: it happens because the biggest customer is the easiest to sell more to, so review quarterly.
This guide is educational and does not constitute financial, accounting, legal, or tax advice. All figures are stylized illustrations using assumed margins, fixed costs, and sales cycles, and do not describe any particular business. Contribution margin, replacement timelines, lender treatment of concentrated revenue, and contract terms vary widely by industry and by counterparty. Consult your accountant and legal adviser before relying on any contract term or financing arrangement described here.