Customer Concentration: What It Costs and How to Fix It
By Mike White, 2-Squared Advisory
Customer concentration is one of the few risks a buyer can quantify in a single spreadsheet — and one of the few that meaningfully discounts every dollar of EBITDA you've worked years to build. The good news: it's also one of the most fixable, if you start 18–24 months before you need to.
How buyers and lenders think about concentration
Three separate analyses happen in diligence:
- Single-customer share: what % is the largest customer?
- Top-3 / top-5 share: stacked concentration risk.
- Customer-by-customer EBITDA contribution: sometimes the biggest customer is also the lowest-margin — the concentration risk and the profitability risk compound.
Each one triggers different discounts. Single-customer above 35% can cost 1x–2x of multiple. Top-3 above 70% can add another 0.5x. Concentration in the lowest-margin customer can be the most punishing of all.
The 18-month diversification plan
Months 1–3: Baseline and target
Pull revenue by customer for the last 24 months. Calculate top-1, top-3, and top-5 share. Look at gross margin by customer too. Set a target: where do you need to be in 18 months — both in customer share and total revenue?
Months 4–9: Sales redirect
Shift sales energy toward adjacent customers — same industry, same buying criteria, smaller size. The goal is many new mid-size customers, not one new large one (you'll just trade one concentration for another).
Months 10–18: Lock in
For new customers crossing meaningful thresholds, formalize contracts and renewals. For the big customer, lock in multi-year terms where possible, but don't pretend the contract solves the concentration problem.
What not to do
- Don't shrink the big customer to "fix" the ratio. Lower revenue is worse than concentration. Grow around it.
- Don't replace one big customer with another. The buyer cares about distribution, not about who.
- Don't ignore vendor concentration. Buyers look at both sides. Sole-source vendor relationships above ~30% also trigger discounts.
- Don't wait until you're 6 months from sale. Concentration is the slowest value driver to fix.
What to do this month
- Pull a 24-month revenue-by-customer report.
- Calculate top-1, top-3, top-5 share, and gross margin by customer.
- Identify the 10 adjacent customers you should be selling to and aren't.
- Set a sales-mix target for 12 and 24 months out, and align comp to it.
Related services
Frequently asked questions
How much customer concentration is too much?
Buyers start asking questions at 20% from a single customer. Above 35%, valuation discounts and earn-out structures get heavy. Above 50%, many buyers walk. Three customers above 60% combined is also a flag.
What if my biggest customer is a long-term contract?
A real multi-year contract with switching costs and meaningful termination penalties helps — sometimes a lot. But buyers still discount, because contracts can be renegotiated and large customers know their leverage. Diversification beats contractual protection.
How do I diversify without losing my biggest customer?
You don't shrink the big customer — you grow around them. The goal is to bring the percentage down by adding new revenue, not by losing old. The right plan focuses sales energy on adjacent customers, not on protecting the existing book.
Will fixing concentration before sale actually pay off?
Almost always. Moving top-customer share from 38% to 22% over 18 months commonly moves multiple by 0.75x–1.25x — on top of the EBITDA you added. For a $1.5M EBITDA business, that's $1.1M–$1.9M of value.