Customer concentration risk is what happens when too much of your revenue comes from too few customers. It's one of the most common value-killers in small and mid-size business sales — and one of the most fixable, if you start early.
What Counts as "Too Much" Concentration?
Most buyers — especially PE firms — get uncomfortable when a single customer represents more than 15–20% of total revenue. At 30%+, expect significant pushback: a lower multiple, a large earnout tied to that customer's retention, or a buyer who walks entirely.
The math is simple: if one customer leaves post-close and takes 30% of revenue with them, the business the buyer paid for no longer exists at that price. Buyers price that risk in.
Concentration thresholds to know: under 10% per customer is clean and raises no flags. 10–20% is noticeable but manageable with good documentation (long-term contract, historical retention data). 20–30% is a yellow flag that requires explanation. Above 30% is a significant issue most buyers will try to structure around through an earnout or purchase price reduction.
Types of Concentration Risk
Customer concentration isn't only about a single client. Buyers also look at:
| Concentration Type | Why Buyers Care |
|---|---|
| Single customer >15–20% of revenue | Direct revenue risk if customer leaves |
| Single industry vertical (e.g., 80% commercial) | Economic sector risk — recession in one industry hits you hard |
| Geographic concentration | Single market — natural disaster, regulatory change, or competition can impact all revenue |
| Revenue from one contract type | 100% project/break-fix with no recurring base |
| Supplier concentration | Single source for key materials creates supply chain risk |
How Buyers Handle Concentration in Deal Structure
When a buyer identifies significant customer concentration, they have several options:
Price reduction: Simply lower the offer to reflect the risk. If the anchor customer leaves, the reduced price better reflects what they'll have paid for.
Earnout tied to anchor customer: The deal closes at the full price, but a portion is held back and paid only if the anchor customer stays for 12–24 months post-close. This shifts the retention risk back to you.
Representations and warranties: Seller is required to rep that no customer relationship material facts have been omitted; breach creates indemnification exposure.
Walk away: For very high concentration (40%+) or where the anchor relationship is clearly personal to the owner, some buyers simply decline to proceed.
How to Reduce Concentration Before You Sell
The most effective fix is straightforward: diversify your customer base. That means actively winning new accounts in commercial and residential — particularly recurring revenue relationships that reduce dependence on any single party.
For plumbing businesses with large commercial anchor clients, consider: negotiating multi-year, assignable contracts with those clients before going to market (a buyer can model the risk better if there's a 3-year contract in place); building a residential service agreement program to create a diversified recurring revenue base; and actively pursuing smaller commercial relationships to spread revenue.
Start this 18–24 months before going to market. Concentration that took years to build won't disappear in 60 days.
→ What Do Plumbing Business Buyers Look For? Customer concentration in context of the full buyer checklist → How to Maximize Value Before Selling Where diversification fits in the value maximization planDISCLAIMER: The information on this page is provided for general informational and educational purposes only. It does not constitute — and should not be construed as — financial advice, investment advice, legal advice, tax advice, or any other form of professional advice. Nothing on this site creates a professional advisory relationship between you and Lightning Path Partners. Business valuations, transaction structures, and market conditions discussed herein are general in nature and may not apply to your specific situation. Always consult a qualified financial advisor, M&A attorney, business broker, or CPA before making any business or financial decisions. Full Terms of Use →
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