Customer concentration, and the point where buyers start walking

A business doing four million with one customer at 40% is a different asset from a business doing four million spread across sixty customers. Same revenue, same profit, materially different price.

Owners generally know this and generally underestimate it, because from the inside a large customer is a success story. You won them, you kept them, they have been loyal for eleven years. From a buyer’s side of the table it is the single largest thing that could go wrong.

Where the discomfort starts

There is no published threshold, and anyone who quotes you a precise one is guessing. What buyer and lender behaviour looks like in practice:

Under 10%. Not a topic of conversation.

10 to 25%. Noted, asked about, priced in lightly. A buyer wants to know how the relationship works and who owns it.

25 to 40%. A real issue. It shapes the structure of the deal rather than just the price. Expect more of the consideration to be contingent, and expect the buyer to want to meet that customer before closing.

Above 40%. Often the central issue in the whole transaction. Some buyers stop looking. The ones who continue are usually strategic buyers who want that specific relationship, which changes who you are selling to and on what terms.

Why lenders matter as much as buyers

This is the part owners tend to miss. Most small business acquisitions involve debt, and the lender is running their own assessment of whether the business can service it after the sale.

A lender looking at 40% concentration is looking at a business where one phone call could remove the ability to make payments. They respond by reducing what they will lend, requiring more equity from the buyer, or declining. Any of those shrinks your buyer pool, and it shrinks it invisibly: you do not hear about the buyers whose financing did not come together.

So concentration can reduce your price without any buyer ever mentioning concentration.

What a buyer is really asking

Not “how big is this customer”. Three narrower questions:

Does the relationship transfer? Is there a contract, and does it survive a change of ownership? Many contracts contain an assignment clause requiring the customer’s consent, which hands that customer leverage at the worst possible moment.

Who owns it inside your company? If the customer’s only relationship is with you, the relationship leaves when you do. If they know your operations lead by name, and that person is in the room for the important conversations, it stays.

Why are they still here? Price, switching cost, genuine preference, or inertia. A customer who stays because moving would be painful is more durable than one who stays because they like you, and a buyer will work out which it is.

What can be done in twelve months

Add revenue elsewhere. The arithmetic here is easier than reducing the large customer, and it does not risk the relationship. Growing the rest of the business by a third takes a customer from 40% to 30% without touching them.

Get it under contract. Even a one-year term with clear renewal language changes the conversation, and it is worth checking the assignment clause while you are in there.

Institutionalise the relationship. Introduce a second person, put them on the calls, make sure the customer’s procurement contact has a name at your company other than yours. This is the same work as reducing owner dependence generally, and it counts twice.

Document why they buy. If a buyer can see the mechanism, whether that is a technical integration, a certification, a location advantage, they can assess the risk. Unexplained loyalty reads as fragile even when it is not.

Do not fire the customer. Owners occasionally propose deliberately shrinking a large account to improve the ratio. This trades real current profit for a hypothetical valuation benefit and usually damages the relationship in the process.

The one that is worth knowing early

Concentration is measured at the point of sale, but it is changed over a year or more of sales effort. An owner who discovers at the point of listing that their largest customer is 45% of revenue has no move available. The same owner eighteen months earlier has several.

Question two of the Exit Readiness Score asks for this figure directly, and question six asks whether your agreements are transferable. Both take a few seconds and neither needs a financial statement.