Customer concentration risk is what happens when too much of a business’s revenue comes from too few customers. In mid-market M&A, the standard threshold that triggers buyer concern is 20 percent — meaning if any single customer accounts for more than 20 percent of total revenue, buyers treat that concentration as a structural risk that must be priced into the deal. At 30 or 40 percent concentration, it becomes one of the primary obstacles to a clean exit at a premium multiple.
Why Concentration Is a Valuation Problem
The concern is simple: if the business’s largest customer leaves after the acquisition — whether because of the ownership change itself or for independent reasons — the cash flow model the buyer purchased changes fundamentally. Buyers who take on that risk either pay less for it, require the seller to absorb part of it through earnout structures, or insist on seller financing tied to customer retention. None of those outcomes benefit the seller.
A business generating $3 million in EBITDA with 40 percent of revenue in one customer is not the same asset as a business generating $3 million in EBITDA with diversified revenue. The first business has a single-point-of-failure in its revenue model that the buyer must account for. The second does not. That structural difference shows up in the multiple — often by two to three full turns.
The Types of Concentration Buyers Evaluate
Customer concentration is the most commonly discussed form but not the only one. Buyers also evaluate geographic concentration — revenue that comes primarily from a single market or region — industry concentration, where most customers operate in the same sector and would be affected by the same macroeconomic conditions, and channel concentration, where a disproportionate share of new business comes through a single partner, referral source, or platform.
How to Address Concentration Before an Exit
Diversifying customer concentration is a multi-year effort that requires deliberate new business development focused on expanding the customer base rather than growing the existing concentration. In some cases, owners resist this because the concentrated customer is highly profitable and growing. The risk is that a business that looks financially strong at the time of sale is structurally weak in a way buyers will not pay a premium to absorb.