The client, the risk and the shift towards a resilient business. Having a large customer is great for cash flow and reputation, but it’s priced as a risk by those looking to buy your business.

Here’s how to ensure you’re not overly dependent on one customer.

Graham Stephen is CEO and co-founder of bizval, a valuation firm that has run thousands of valuations across multiple markets. A chartered accountant by training, he lists customer concentration among the risks that quietly drag a valuation down, and it’s one founders almost never see coming.

Founders see a big customer as revenue. Buyers see them as risk, a concentration that makes future cash flows less certain, which is exactly what pulls a valuation down. Learn to look at your customer base the way an acquirer will.

“If one client is 40% of your revenue, a buyer doesn’t see a great customer; they see the risk of losing 40% of the business overnight.”

Pull your revenue by customer for the last year and turn it into percentages. Not a vague sense of who your big clients are, but the actual numbers. What percentage of total revenue does your largest customer represent? Your top three?

Founders are regularly surprised here. The client that feels like one of several often turns out to be a third or more of the whole business. You can’t manage a concentration you haven’t measured.

As a rule of thumb, once a single customer is more than around 20% of revenue, concentration starts to look like a real risk to an outside buyer. The higher above that, the sharper the discount on your value.

Be honest about how replaceable that revenue actually is. If your biggest client left tomorrow, how long to replace them, and could you survive the gap? If the honest answer is “we’d be in serious trouble,” you’ve found the risk that’s capping your number.

Concentration isn’t always one named client. It can hide in a single industry or channel. An SA business that sells almost entirely to the big retailers, or one that lives off municipal and government contracts, is concentrated even across several “different” customers, because they all move together, and one policy or budget shift hits all of them at once.

Look past individual logos to the underlying dependence. If most of your revenue rises and falls with one sector’s fortunes, that’s concentration too, and a buyer will treat it the same way.

Once you’ve seen the risk, the fix is to spread the base. Deliberately grow revenue from other customers and sectors so no single relationship holds your business hostage. It won’t happen by accident — the gravity of a big client always pulls you toward serving them more.

Every step toward a broader, more balanced customer base makes your future cash flows more certain, and more certain cash flows are worth more. Reducing concentration isn’t just safer — it directly lifts the number a buyer will pay.

Measure your concentration and you turn an invisible risk into something you can manage. You protect the business from the day your biggest client walks, and you remove one of the quiet detractors dragging down your valuation — so the number reflects the business you’ve actually built.

It takes an afternoon to run the numbers. Fixing what they reveal is slower — which is exactly why you want to see it years before you sell, not at the negotiating table.

This is one piece of Business Valuation for Founders, Graham’s full masterclass inside the Founder Collab. It’s part one of a three-part series that takes founders from understanding their number to actively growing it:

You’ll also get access to 40+ other masterclasses from SA founders and operators on sales, fundraising, UX, paid media and more inside The Founder Collab.

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