Customer concentration: the risk hidden inside strong revenue

Some of the most commercially exposed SMEs report their strongest revenue. The order book is full, the relationships are long-standing, and the largest accounts are growing. The exposure sits underneath: a small number of customers account for most of the revenue, and the business's plans, pricing and capacity have quietly been shaped around keeping them.

Why concentration develops — and why it feels like success

Concentration is usually the by-product of doing good work. A major customer is won, served well, and grows. Serving them consumes commercial attention that might otherwise have gone into developing new accounts. Each individual decision — prioritising their orders, accepting their terms, investing in their requirements — is rational. The cumulative result is a business whose fortunes are tied to decisions made in someone else's boardroom.

This is why concentration is so persistent: it does not feel like a problem. It feels like a strong relationship. The risk only becomes visible when the customer restructures, re-tenders, insources, or is acquired — events the supplier neither controls nor, often, sees coming.

The indicators that matter most

Share of revenue — and share of margin

The standard measure is the share of revenue held by the largest customer and the largest three to five. But margin concentration is often more revealing: a customer taking thirty per cent of revenue at thin, hard-negotiated margins represents a different exposure from one taking thirty per cent at healthy margins. Both figures should be known, and tracked over time rather than glanced at once.

Dependence beyond revenue

Concentration is not only financial. A customer can dominate production capacity, tooling investment, technical development or management attention. A business whose engineering roadmap is effectively set by one account is concentrated, whatever the revenue split says.

The terms of the relationship

Who holds the contractual power? Rolling short-notice arrangements, unilateral rebate schemes, extended payment terms and open-book pricing all indicate a relationship where the customer can adjust the economics at will. The commercial risk of concentration is not only that the customer leaves — it is that they stay, on progressively worse terms.

The state of the rest of the pipeline

The most important indicator is often the counterfactual one: how much genuine new-business activity exists outside the major accounts? A concentrated business with a healthy, independent pipeline is managing its risk. A concentrated business whose "business development" consists of serving existing accounts is compounding it.

What managing concentration actually involves

The answer is rarely to reduce dependence by turning away good business. It is to change the balance of effort and evidence around it:

• Know the numbers. Revenue, margin and capacity share by customer, reviewed regularly, so that drift is a decision rather than a discovery.
• Strengthen the relationships you have. Broaden contact beyond a single buyer, understand the customer's own strategy, and secure terms that reflect the investment being made on their behalf.
• Build genuinely new demand. Ring-fence commercial capacity for developing accounts that are not the major customer — because if that capacity is shared, the major customer will absorb it.
• Plan the scenario. Knowing in advance what the business would do if its largest account halved is not pessimism; it is the difference between a controlled response and a crisis.

Concentration itself is neither good nor bad — most successful SMEs pass through periods of it. What separates resilient businesses from exposed ones is whether the dependence is measured, priced and actively managed, or simply relied upon.