Why lenders and buyers worry when one customer is a large share of revenue, and practical ways to reduce the risk before you sell.
The risk in plain terms
If one customer is a third of your revenue, losing them could cut the business's earnings by more than a third overnight. Buyers price that risk. Lenders may refuse to count that revenue as reliable.
Where the lines tend to be
There is no universal cutoff, but many buyers and lenders start asking questions when a single customer passes roughly 10–20% of revenue. At a third or more, expect lower offers, tougher terms, or both.
It's worse when the relationship is personal
Concentration that sits on a handshake with you is the hardest kind to transfer. A written contract, a second point of contact at your company, and a documented history of the account all help show the revenue would stay after the sale.
Ways to reduce it
Sign multi-year agreements with your largest accounts. Introduce another person from your team to each major relationship. Grow other customers so the big one becomes a smaller share, even if its dollars stay the same. Show the revenue history of the top accounts so a buyer can see how stable they have been.
Timing
This takes months, not weeks. Work on it a year or more before you plan to sell, and re-check the numbers as you go.
This article covers general lending and deal practices and is not legal, tax or financial advice, or a guarantee of loan approval or terms for any specific business. Lender criteria vary, so talk to your CPA, attorney and lender about your situation.