The 30 per cent threshold: qualitatively distinct
Customer concentration is a financial variable the industrial executive committee reviews when the significant account enters difficulties, and rarely before. Investment in analysing it when all is well is usually low, which explains why its impact on corporate valuation and on the strategic autonomy of the company remains underestimated in many mid-sized operations.
The academic literature (Patatoukas, The Accounting Review 2012; Itzkowitz, Banerjee, Cen et al.) and the practice of Wall Street Prep / Allianz Trade documented in 2024 the reference thresholds different financial analysts apply when assessing concentration risk in industrial companies. The line of attention is usually placed when an individual customer represents more than 15-20 per cent of revenue. The line of serious risk is placed above 30-40 per cent. In specific industrial-hardware sectors, concentration of the top ten customers around 30-60 per cent of revenue is typical, which adds structural vulnerability to the model.
| % of revenue from main customer | Reading | Financial implication |
|---|---|---|
| < 10% | Low concentration | No valuation discount |
| 10-20% | Moderate concentration | Moderate, governable discount |
| 20-30% | Material concentration | 10-20% discount; specific due-diligence |
| > 30% | Critical concentration | 15-30% discount; many funds operationally reject |
A complementary figure on Spanish business demography adds context. The average life expectancy of the Spanish SME is 11 years, against an EU average of 19.6 years. A good part of the difference is attributed to more concentrated customer structures and to lower capacity to absorb the loss of significant accounts. Concentration is not only financial risk. It is a structural predictor of business longevity.
Why the dynamics change: three structural effects
When a customer represents more than 30 per cent of a supplier's revenue, the dynamics of the relationship change qualitatively. The customer ceases to be one more customer and becomes a constraint on the supplier's strategic decisions. Investments in product are adjusted to their needs. Delivery deadlines are rearranged according to their priorities. Commercial terms are renegotiated periodically under power asymmetry. In practical terms, the supplier operates as an outsourced division of the customer, without formally having that condition or receiving the consideration that formalisation would imply.
The frequent error in the executive committee is to celebrate concentration as a sign of commercial success without measuring its strategic cost. A customer who grows within the company is good news up to a certain threshold. Beyond that threshold, additional growth erodes autonomy, corporate valuation and bargaining power, without the income statement reflecting it with immediate clarity.
Three levers to govern the risk
Three levers move the indicator in companies that address the problem with discipline. Establish explicit maximum concentration limits per customer, per sector and per geography, defined by the executive committee and reviewed annually. Build a formal diversification programme that allocates specific commercial resources to developing alternative accounts in adjacent sectors. Negotiate contractually with the customers approaching the threshold conditions that protect the supplier's autonomy: multi-year contracts with termination penalties, regulated exclusivities, orderly exit mechanisms.
For general management, the organisational implication is direct. Managing concentration risk is not a function of the commercial area. It is a function of the executive committee, which must assign the authority and the resources necessary to sustain diversification discipline even when it contradicts immediate commercial logic.
The objection of additional growth
The standard objection is that refusing additional growth with an important customer is counter-intuitive and, in some cases, commercially risky. The objection is accurate in the short term and mistaken in the medium. Companies that accept unlimited growth with their largest account often discover that the dependence built during years of plenty turns into vulnerability when the account changes leadership, strategy or supplier for reasons unrelated to the supplier's own performance.
Recognising concentration as a first-order strategic risk, and governing it with discipline before it materialises as a crisis, is one of the decisions that most distinguishes industrial companies that sustain growth from those that lose it for causes which at the time were perceived as success.