A practical guide to customer concentration due diligence — how PE, search funds, and M&A buyers size top-account risk, contract durability, and what a lost logo does to underwriting before confirmatory commercial work opens the full cohort file.
Blended revenue growth can hide a brittle book of business. If one customer is 22% of revenue and that account is in rebid, the investment case is not a market story — it is a single relationship story. Customer concentration due diligence forces the pyramid into the open: revenue share, gross-profit share, contract status, switching costs, and who actually owns the account.
Lenders, limited partners, and investment committees often apply informal or explicit thresholds. Crossing them does not automatically kill the deal, but it changes price, structure, earnouts, and the credibility of a clean exit narrative three to five years out.
| Pillar | Core question | Typical evidence |
|---|---|---|
| 1. Pyramid & thresholds | How concentrated is revenue and profit? | Top 1 / 5 / 10 / 20; HHI-style view; GP by account |
| 2. Contract durability | What is legally sticky vs at-will? | MSA/SOW terms, renewal, T&C, termination for convenience |
| 3. Economics by account | Are big logos profitable? | Gross margin, discounting, service burden, CAC payback |
| 4. Churn & retention path | Who left, who expanded, why? | Logo/net retention, win-loss, pipeline by existing accounts |
| 5. Buyer power & switching | Can they leave or reprice you? | Alternatives, multi-source policy, integration depth |
| 6. Close & go-forward | What do we protect post-close? | Reps, earnouts, key-person, Day-1 retention plan |
Traditional customer / commercial work often runs $25K–$150K+. A structured first-pass PDF pack starts at $49 (or $39.20 with code DI20-WELCOME) so you can kill fragile pyramids early.
Document the threshold your IC or credit committee cares about before you fall in love with blended CAGR slides.
| Stage | Concentration focus | Output |
|---|---|---|
| Pre-LOI / CIM | Disclosed top customers, segment mix, obvious thresholds | Go / no-go flags; price implications |
| LOI / exclusivity | Cohort file request list; known rebids; key-person map | Diligence plan + data-room ask |
| Confirmatory | Contracts, margin by account, reference calls, pipeline truth | Risk register + underwriting adjustments |
| SPA / close | Reps, schedules, earnouts, retention bonuses | Protective structure |
| 100 days | Account plans, dual-cover sales, expansion vs defense | Value-creation roadmap |
| Severity | Signal | Why it matters |
|---|---|---|
| Deal-killer | Top customer already issued termination or lost rebid not yet in CIM | Revenue hole is near-term and non-negotiable |
| Deal-killer | One customer > IC/lender threshold with no retention path or dual cover | Financing and thesis break |
| High | Gross margin on top accounts well below company average | Scale is value-destructive |
| High | Relationship sits with one salesperson or founder only | Key-person + post-close flight risk |
| High | Multi-year decline in share of wallet despite "strategic partnership" language | Narrative vs data conflict |
| Watch | Customer multi-sourcing policy expanding | Volume and price pressure ahead |
| Watch | Contract up for renewal inside hold period with weak switching costs | Earnout / covenant sensitivity |
| Watch | Channel partner concentration (distributor / marketplace) | Indirect customer risk |
| Approach | Typical cost | Timeline | Best for |
|---|---|---|---|
| Full commercial + customer deep-dive | $25K–$150K+ | 3–8 weeks | Confirmatory on shortlist |
| Expert network + win/loss only | $10K–$40K | 1–3 weeks | Hypothesis tests |
| Structured first-pass public pack | $49 ($39.20 with DI20-WELCOME) | Minutes to hours | Pre-LOI triage across many names |
Use cheap structured screening to decide which names deserve expensive commercial firepower. Do not spend $75K learning that the top customer was always going to leave.
| Workstream | Primary question | Overlap with concentration |
|---|---|---|
| Commercial DD | Will the market keep buying? | Pricing, competition, GTM — concentration is the account-level cut |
| Financial DD | Are the numbers real and sustainable? | Revenue quality, backlog, DSO, one-time spikes |
| Quality of earnings | What is normalized earnings power? | Customer-driven adjustments and run-rate holes |
| People DD | Who makes the machine run? | Key-person account ownership |
| Customer concentration DD | How much of the P&L sits on a few logos? | Core: pyramid, contracts, retention, buyer power |
Before you fund a full commercial deep-dive, use a structured public and CIM screen to rank targets: disclosed logos, segment mix, channel dependence, peer concentration norms, and obvious threshold breaches. Kill brittle pyramids early. Save expert calls and contract attorneys for names that clear the first filter.
dodilligence delivers institutional-style first-pass PDF packs from public information so deal teams can screen more names per week. It is not a customer reference program, audit, or legal opinion — it is triage research that makes confirmatory scopes sharper.
Order a first-pass diligence PDF on your target — revenue durability clues, public footprint, and IC-ready questions — for $49 or $39.20 with code DI20-WELCOME. Or compare three names with the 3-Pack.