Customer concentration is the share of revenue coming from a small number of customers. US filers must disclose any customer representing 10% or more of revenue. It matters because losing one such customer is not a bad quarter, it is a permanent step down in the size of the business.
Where to find it
In the 10-K, usually in the business section or the segment note, in language like "one customer accounted for 23% of net revenue." It is a required disclosure above 10%, so its absence is meaningful: a company with no customer above that threshold genuinely has a diversified base.
Read several years together. A company where the top customer went from 12% to 31% is becoming a supplier to one buyer, whatever its own description of itself says.
Why it caps the multiple
Concentration changes who holds the power in the relationship. A customer worth a third of revenue can demand price cuts, longer payment terms and priority, and the company has no real ability to refuse. That shows up over time as compressing gross margin and stretched working capital, both of which are the concentration being exercised rather than separate problems.
It also caps what the market will pay. Two companies with identical growth and margins are not worth the same if one of them can lose 30% of its revenue in a single phone call. The concentrated one trades at a discount, correctly, and the discount does not close until the concentration does.
When it is genuinely fine
When the customer cannot leave. A component designed into a product for a decade, with requalification costs measured in years, is a concentrated relationship with the power running the other way. Switching costs invert the risk.
When the customer is a channel, not an end customer. Selling half your volume through one retailer is different from selling half to one buyer, because the underlying demand is diversified even though the invoice is not.
Early in a company's life. A young company with three customers is normal. What matters is the direction: concentration falling as revenue grows is a business finding its market. Concentration rising is a business becoming a contractor.
What to check alongside it
Look for contract length and renewal dates, which are often disclosed, and for whether the relationship is sole-source or one of several suppliers. Then check receivables: if one customer is a third of revenue and receivables are climbing faster than sales, the company is financing its largest customer, which is the weakest possible position from which to negotiate the next contract.
Find the risks before you buy
Stock Simplifier surfaces the risk factors and revenue detail for any US stock, including who the business actually depends on. Free to start.
Try Phase Check freeNo credit card. One check without an account, unlimited with a free one.
Frequently asked questions
Related
- How to read a 10-K, where the disclosure lives and what surrounds it.
- Stock red flags, the other warnings that sit alongside this one.
- Switching costs, what turns a concentrated customer from a risk into a moat.
- Gross margin, where a powerful customer's demands eventually show up.