One Customer Is Too Much of My Revenue: Can I Still Sell?

If one customer represents 20%, 30%, or 50% of revenue, the business is not automatically unsellable. But the buyer will not value that revenue the same way they value a broad, repeatable, diversified customer base.

Lyndon Advisory helps business owners confidentially review customer concentration, valuation risk, buyer universe, and whether a sale process should start now or after preparation. For the wider sale-readiness context, see our guide to selling a business.

Concentration issue	Buyer concern	Seller preparation
One customer above 20-25% of revenue	Earnings could fall sharply if the customer leaves.	Contract status, renewal history, and customer relationship map.
Top 3 customers above 40-50%	Revenue quality may be fragile.	Diversification plan and pipeline evidence.
Founder owns the relationship	Relationship may not transfer after closing.	Multi-contact coverage and transition plan.
Contract is short-term or informal	Buyer cannot underwrite future revenue confidently.	Signed terms, renewal evidence, and referenceable history.
Customer margin is unusually high	EBITDA may be more exposed than revenue suggests.	Customer-level gross margin and pricing history.

Why Buyers Care So Much

Customer concentration is a revenue-quality issue. Buyers are not only asking “how much EBITDA does the company generate?” They are asking whether that EBITDA can survive new ownership.

Public-company reporting rules also reflect the importance of major customers. Deloitte’s ASC 280 guide notes that public entities disclose revenue from a single external customer when it equals or exceeds 10% of total revenue. The private-company M&A threshold is not identical, but the principle is the same: reliance on one customer is material information.

Quality of earnings work also tests revenue durability. Baker Tilly describes quality of earnings as a process that identifies items affecting business value and helps streamline a sale. In practice, top-customer revenue, contract terms, renewal history, and customer margin are standard buyer diligence areas.

High Concentration Does Not Always Mean a Bad Business

Some excellent businesses have high customer concentration because they serve enterprise accounts, government agencies, large retailers, or long-term industrial customers. Concentration is less damaging when the customer relationship is contracted, multi-year, profitable, operationally embedded, and not dependent on the founder personally.

The problem is unprotected concentration. A 35% customer with no contract, declining margins, a single founder relationship, and no documented renewal history is very different from a 35% customer under a multi-year agreement with multiple operational contacts and proven reorder behaviour.

How Buyers Change the Deal

When buyers see customer concentration, they usually respond in one or more ways:

• reduce the EBITDA multiple;
• require an earnout tied to customer retention or revenue;
• hold back part of the purchase price;
• request customer calls earlier in diligence;
• require the founder to stay longer after closing;
• delay exclusivity until the relationship is understood;
• ask for representations that no key customer termination is expected.

That does not mean the seller should volunteer customer names too early. It means the seller should prepare a staged disclosure plan: anonymous customer concentration summary first, contract and renewal evidence later, and direct customer contact only when confidentiality protections and transaction certainty justify it.

What to Prepare Before Talking to Buyers

Prepare a short customer concentration pack before buyer outreach:

• top 10 customers by revenue for the last three years;
• revenue, gross margin, and trend by key customer;
• contract status, expiry dates, renewal terms, and change-of-control provisions;
• relationship owner and secondary contacts for each key customer;
• customer tenure and reorder or renewal history;
• known risks, disputes, pricing pressure, or churn signals;
• customer references that may be available later in the process;
• actions already taken to diversify pipeline or account coverage.

“Customer concentration is not just a percentage. Buyers want to know whether the relationship is contractual, operationally embedded, and transferable. Sellers who prepare that answer before diligence protect value much better than sellers who wait for the buyer to discover the risk.”

— Daniel Bae, Founder & CEO, Lyndon Advisory, former M&A advisor with over US$30 billion in transaction experience.

Sell Now or Fix It First?

Situation	Practical route
Largest customer below 15%	Disclose cleanly and focus on broader valuation drivers.
Largest customer 15-25%	Prepare detailed customer evidence before launch.
Largest customer above 25%	Expect buyer scrutiny and consider 6-18 months of diversification if timing allows.
Buyer has already approached	Do not share customer-identifying information or grant exclusivity until valuation and alternatives are understood.

If concentration exists because the founder personally owns customer relationships, also read My Business Depends on Me: Can I Still Sell It?. If a buyer has already approached, read Private Equity Approached My Company: What Should I Do?.

When to Ask for Help

Ask for help before a buyer uses concentration to justify a low price, before direct customer contact is requested, or before you agree to an earnout that depends on a customer you do not fully control.

If one customer is too much of your revenue, submit a confidential valuation inquiry. Lyndon Advisory can review likely buyer reaction, valuation range, customer-disclosure sequencing, and whether preparation or a sale process is the right next step.

Sources

• Deloitte DART, ASC 280 major customer disclosure
• Baker Tilly, quality of earnings report in pre-sale due diligence
• Cornell Legal Information Institute, 17 CFR § 229.101

Related Reading

• Guide to Selling a Business
• Customer Concentration
• Business Exit Readiness Assessment
• My Business Depends on Me
• How Earnouts Work in M&A