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Customer Concentration: Why Buyers Draw the Line Around 20%

Losing your largest customer the week after closing is a buyer's worst-case scenario — and the more of your revenue that customer represents, the more that scenario shapes the offer you get.

Where buyers start paying attention

There's no universal legal threshold, but in practice buyers start scrutinizing a single customer once it crosses roughly 20% of revenue, and concentration above 50% is treated as a severe risk that can affect not just price but whether a deal happens at all.

The concern isn't abstract — it's about what a buyer is actually purchasing. If a third of your revenue depends on one relationship, a buyer is effectively underwriting the durability of that one relationship, not just the business as a whole.

What matters beyond the raw percentage

A concentrated customer under a signed, multi-year contract is a meaningfully different risk than the same concentration resting on an informal, decades-long relationship with no paper behind it — even though both show up identically as "50% of revenue" on a spreadsheet.

Buyers also look at why the concentration exists: is it because the business has genuinely earned an outsized share of one large client's spend (which can be a strength, if durable), or because the business never invested in sales and business development beyond one relationship (a weakness)? Top-five customer concentration, not just the single largest account, factors in too — a business with five customers at 15% each carries different risk than one with one customer at 45% and the rest fragmented.

What actually reduces the risk

Formalizing the relationship under a longer-term contract is the fastest lever if the relationship itself is healthy — it converts an informal dependency into a documented, transferable one. Beyond that, the only real fix is diversification: adding customers, expanding into new segments, or growing other accounts faster than the concentrated one, which takes time and can't be manufactured in the run-up to a sale.

If concentration can't be meaningfully reduced before going to market, expect it to show up in deal structure rather than just price — buyers sometimes address concentration risk through an earnout tied to retaining the key account, rather than paying full value for revenue they're not fully confident will survive the transition.

See how customer concentration moves your own estimate →See how this can shape deal structure, not just price →