Having a few large, dependable customers looks comfortable at first sight: settled relationships, predictable volumes, less daily selling effort. But that comfort hides a structural risk that only shows itself when one of them stops ordering.
How concentrated is too concentrated
There is no universal threshold, but a clear warning sign is when one or two customers alone account for enough revenue that losing them would threaten the firm's viability in the short term. Working out that percentage, even roughly, is the first step to seeing the real risk.
Why large customers can vanish without warning
An important customer can cut orders for reasons entirely unrelated to the quality of your service — an internal reorganisation, a change of supplier on price, difficulties of their own. It is not a risk you prevent by serving them better: it is structural to the concentration itself.
Diversifying without giving up the large accounts
Diversifying does not mean stepping back from your main customers, but investing in parallel in winning new medium-sized ones, which over time reduce the percentage weight of the largest without having to give up any of them. It is continuous commercial work, not a one-off exercise.