Customer concentration is the share of revenue tied to a small number of customers. When you sell a business, buyers will want to know more than the largest customer’s percentage: they will ask whether the earnings from that account are likely to continue after ownership changes. A concentrated customer base does not automatically rule out a sale. It does make the durability of those relationships a diligence question.

For an industrial or business-services company, the useful starting point is a customer-level schedule that reconciles to financial statements. Then look at five dimensions: revenue, gross profit, common ownership, contractual terms, and who owns the relationship. That gives you a clearer picture of what a buyer may be underwriting and what you can substantiate before going to market.

Why the Headline Percentage Is Only a Starting Point

Imagine two businesses that each earn 30% of revenue from one customer. Hypothetically, one has several years of repeat work across multiple facilities, contacts at several management levels, and agreements with documented renewal history. The other relies on sporadic projects approved by one executive. The same revenue percentage describes different risks.

Commercial diligence commonly examines customer concentration and buying behavior, while financial diligence tests whether earnings are sustainable. That is why an owner should be ready to explain the quality of concentrated revenue, not merely its size.

There is no universal customer-share percentage that determines whether a private company is saleable or what it is worth. Avoid treating a public-company disclosure threshold or an online “valuation discount” as a rule for your transaction. Buyer fit, contract terms, margins, switching costs, and the direction of the relationship all matter.

Build a Five-View Concentration Schedule

Start with three years of customer-level revenue and a current trailing-twelve-month view, using consistent customer names and a reconciliation to the general ledger. Then add these five views:

1. Revenue share. Show the top customers by year, the percentage of total sales, and whether their contribution is rising or falling. Separate one-time project revenue from ongoing service work.
2. Gross-profit share. A large account with low margins may have a different earnings implication from a smaller but highly profitable one. Use a consistent costing method and document any allocations.
3. Parent-company exposure. Multiple plants or subsidiaries may sit under one parent or purchasing organization. Identify legal entities, ultimate parents, and any shared procurement decision-maker so the schedule does not make one economic relationship look like several independent customers.
4. Contract durability. Record agreement type, remaining term, renewal and termination provisions, change-of-control provisions, and the history of actual orders. Have counsel review legal interpretation; an agreement is not a guarantee of future revenue.
5. Relationship ownership. Note who manages each account day to day, how many contacts exist on both sides, and whether sales depend primarily on the founder or a broader team. Prepare an accurate transition plan, not an assurance that a customer will stay.

This five-view schedule is a preparation framework, not a proprietary valuation formula. Its purpose is to surface questions early enough to gather evidence and address avoidable gaps.

What to Prepare Before a Buyer Asks

For each major customer, collect the signed agreements and amendments, annual sales and gross profit, order or project history, renewal dates, backlog where applicable, and a factual explanation of any major change. Check that customer names and totals agree across the CRM, billing data, and financial statements. If they do not, resolve the differences before circulating materials.

Also identify what the buyer will need to test. Does the relationship survive a change in the founder’s role? Are volumes committed, forecast, or simply historical? Can contracts be assigned? Is a top account tied to one facility, end market, or person? Where evidence is incomplete, say so and build a plan to obtain it. Pre-sale diligence is valuable partly because it exposes these issues before they interrupt a live process.

Should You Wait to Diversify Before Selling?

Sometimes, but not automatically. If new-customer growth can be shown in reliable financial periods without distracting management or weakening margins, it may make the business easier to evaluate. If diversification would require a speculative expansion or delay an otherwise sensible sale, the trade-off may be different. The decision belongs in a broader review of business value, owner goals, timing, and strategic alternatives, not a single concentration ratio.

An owner can still improve readiness without promising to “fix” the percentage: document account history, broaden operational relationships where appropriate, reduce founder-only knowledge, and make the revenue bridge understandable. A buyer may still price or structure the risk differently. Preparation makes that discussion more informed; it does not guarantee a particular valuation or deal structure.

The Practical Next Step

If you are considering a sale, ask your finance and commercial teams for the five-view schedule above and test it against the questions a buyer is likely to ask. Meliora’s sell-side advisory and valuation and strategic alternatives work are relevant when you need to assess concentration alongside the rest of the business. You can contact the team to discuss your situation.