A company with one customer worth 30% of revenue and a company with the same revenue spread across two hundred customers are not, to a lender or an acquirer, the same business — even if every other line on the income statement matches. The market has already worked out how much that difference is worth. Most boards never ask.
Customer concentration is one of the most heavily studied risk factors in corporate finance. The finding holds up wherever it’s tested: a supplier that depends on a small number of major customers pays more for capital than one that doesn’t. Dhaliwal, Judd, Serfling and Shaikh ran the numbers on a large sample of US suppliers and found that concentration raises the cost of equity — sharper still for suppliers likely to lose a major customer, or badly exposed if they do (Journal of Accounting & Economics, 2016). The debt side tells the same story. A more recent study found concentrated-customer firms carry higher cash-flow volatility, adjust their leverage more slowly, and get held to a real valuation discount by investors who have already priced the risk in (Rehman, Liu, Wu and Li, Accounting & Finance, 2023).
None of this is exotic. It’s the market doing what markets do — pricing a risk, whether or not the company itself has bothered to quantify it. A board that has never calculated its own top-five customer concentration isn’t avoiding the number. It’s just letting someone else calculate it first. Usually a lender’s credit committee, or a buyer’s diligence team, at the exact point where the number is hardest to improve and most expensive to be surprised by.
