Client concentration is the percentage of total revenue derived from any single client or group of clients. For professional services firms, it is a primary risk metric — a single client representing more than 20% of revenue creates existential dependency. The formula is: Client Concentration = (Client Revenue ÷ Total Revenue) × 100. Industry risk thresholds are: below 15% per client (healthy), 15–25% (elevated), above 25% (high risk). The risk applies at both the individual client level and cohort level — when the top 3 clients represent 60% of revenue, the firm is structurally dependent regardless of any single client's share.
The Formula
Track concentration at the single-client level and at the portfolio level. Both dimensions matter for a complete risk picture.
- Top-N Concentration = Sum of revenue from N largest clients ÷ Total revenue × 100
- Revenue from Client — all fees and recurring revenue from that client in the period
- Total Annual Revenue — firm-wide recognized revenue for the same period
Worked Example
25-Person Management Consultancy — $5M Revenue
Top 5 clients: Client A = $1.4M (28%), Client B = $850K (17%), Client C = $700K (14%), Client D = $500K (10%), Client E = $350K (7%). Top-5 concentration = 76%.
Single-client risk is critical: if Client A (28%) leaves, the firm loses $1.4M in revenue — nearly equivalent to 8 staff members. To maintain profitability at current overhead, the firm must replace that revenue within 90 days or cut headcount.
At a 4x EBITDA acquisition multiple, this concentration alone typically reduces the firm's marketable valuation by $500K–$1.5M.
Risk Thresholds by Metric
These thresholds reflect typical M&A due diligence standards and acquirer risk tolerance. All benchmarks are estimates.
| Metric | Low Risk | Elevated Risk | High Risk |
|---|---|---|---|
| Single client concentration | <15% | 15–25% | >25% ESTIMATE |
| Top 3 client concentration | <35% | 35–55% | >55% ESTIMATE |
| Top 5 client concentration | <50% | 50–70% | >70% ESTIMATE |
| Typical acquirer comfort (single client) | <15% | Flag at due diligence | Discount or block deal ESTIMATE |
Common Mistakes
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1Measuring concentration by project count instead of revenue
A client with 10 small projects can represent 5% of revenue. A client with 1 large retainer can represent 35%. Always measure by revenue, not engagement count.
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2Missing indirect concentration
Multiple clients in the same industry or procurement channel can create correlated risk. If 60% of revenue comes from financial services clients and the sector cuts budgets, it behaves like client concentration even if no single client exceeds 15%.
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3Not tracking trend direction
A client at 18% today may have been 12% a year ago and growing. Trending concentration is as important as current level — flag clients whose share is growing faster than the overall portfolio.
Why It Matters for Valuation
Client concentration is a deal-breaker metric in M&A. Acquirers model the probability of client retention post-acquisition and discount accordingly. A firm with no client above 15% commands a clean multiple. A firm with a single 35% client will face earnout structures, escrow holdbacks, or outright pass.
Beyond M&A, high concentration constrains pricing power — you can't raise rates on a client who represents 30% of your revenue without risking catastrophic loss.