Due Diligence: 10 Red Flags That Should Alert You

by | 28 Apr 2026

Detect Warning Signals Before It’s Too Late

Introduction

In due diligence, certain warning signals should immediately raise your vigilance. These red flags don’t necessarily mean abandoning the acquisition, but they require thorough investigation and may justify price adjustment or strengthened guarantees.

Here are 10 critical red flags to monitor during your due diligence.

 

Red Flag 1: Exceptional Performance in Year N

The Symptom

Current year EBITDA is 30-50% above 3-year average, thanks to one-time event: exceptional large contract, non-recurring subsidy, or favorable currency gain.

Why It’s Serious

Seller will value company on this artificially elevated Year N performance. You risk overpaying by 30-40% if you don’t restate these exceptional items.

Actions to Take

  • Request detail of all exceptional revenues and expenses over 3 years
  • Calculate normalized EBITDA excluding these items
  • Use weighted 3-year average rather than just Year N
  • Base valuation on recurring performance, not on peak
  • Require performance guarantees or earn-out if seller maintains valuation

Concrete example:

EBITDA Year N  : €500K (includes €200K subsidy)

EBITDA Year N-1: €320K

EBITDA Year N-2: €310K

Normalized EBITDA N: €300K (500 – 200)

3-year average: €310K ← Realistic valuation base

Red Flag 2: Working Capital Exploding with Growth

The Symptom

Revenue grows 20% annually, but working capital requirement increases at same pace. Despite good profitability, cash never materializes.

Why It’s Serious

“Cash trap”: company must permanently finance growth. Each euro of additional revenue requires 20-30 cents financing. You’ll need to massively inject cash to continue growing.

Actions to Take

  • Calculate WCR as % of revenue over 5 years (trend)
  • Analyze details: DSO (customer terms), DIO (inventory turnover), DPO (supplier terms)
  • Calculate cash conversion: Free Cash Flow / EBITDA (target > 60%)
  • Model future financing needs
  • Provision cash or negotiate sufficient credit line

 

Red Flag 3: Excessive Customer Concentration

The Symptom

Top 3 customers represent over 50% of revenue, or single customer exceeds 25%.

Why It’s Serious

Catastrophic loss if major customer leaves post-acquisition. Completely unbalanced bargaining power: customer can impose prices and terms. At-risk valuation due to fragile revenues.

Actions to Take

  • Analyze major customer contracts (duration, notice, change-of-control clauses)
  • Measure historical retention rate
  • Verify existence of letters of intent to continue
  • Adjust valuation according to risk (20-40% discount)
  • Negotiate earn-out linked to major customer retention

 

Red Flag 4: Key Person Dependency

The Symptom

Executive or key employee centralizes all customer relationships, holds all technical know-how, or makes all operational decisions without delegation.

Why It’s Serious

Post-acquisition departure = possible business collapse. You’re potentially buying empty shell. Customers and suppliers are often loyal to person, not company.

Actions to Take

  • Identify all key persons and assess departure impact (score 1-10)
  • Request detailed org chart with tenure
  • Analyze who holds which critical relationships and skills
  • Negotiate retention clauses
  • Require minimum 12-18 month transition support
  • Plan skills and relationship transfer from Day 1

 

Red Flag 5: Contracts Expiring Simultaneously

The Symptom

Main customer contracts (representing 40-60% of revenue) all come up for renewal within 12-18 months after acquisition.

Why It’s Serious

Massive uncertainty about future revenues. Customers may leverage change of control to renegotiate downward or not renew. Enormous pressure on first 12 months.

Actions to Take

  • List all contracts with expiry dates
  • Obtain letters of intent to renew from main customers
  • Negotiate early renewal before closing (with seller)
  • Prepare pessimistic scenario (20-30% revenue loss)
  • Structure earn-out linked to actual renewal
  • Plan proactive commercial approach from Day 1

 

Red Flag 6: Abnormally Low Provisions

The Symptom

Risk and expense provisions represent less than 2-3% of revenue, while sector benchmarks are 5-8%. History of significant litigation but minimal provisions.

Why It’s Serious

Underestimation of actual liabilities. Costs will inevitably emerge post-acquisition (litigation, warranties, compliance). You inherit time bombs not provisioned.

Actions to Take

  • Benchmark provisions vs sector listed competitors
  • Request exhaustive list of identified risks (even unprovisioned)
  • Analyze 5-year litigation history and actual cost
  • Question insurers about recent claims
  • Provision safety cushion (3-5% of price) in your model
  • Negotiate extended liability warranties

 

Red Flag 7: Change of Control Clauses

The Symptom

Major contracts (customers, suppliers, partners, financing) contain clauses allowing termination or renegotiation upon shareholder change.

Why It’s Serious

Potential loss of key contracts or unfavorable renegotiations immediately post-acquisition. Business model may collapse. Counterparties may exploit your weakness to impose new terms.

Actions to Take

  • Systematically review all major contracts
  • Identify all ‘change of control’ clauses
  • Quantify impact if terminated (% of revenue, criticality)
  • Negotiate waivers (clause removals) BEFORE closing
  • Obtain letters of continuity from key partners
  • Condition closing on obtaining these waivers
  • Prepare replacement scenarios if refused

 

Red Flag 8: Gap Between Cash and Profit

The Symptom

Company shows solid accounting profitability (positive net income), but generates little or no cash. Cash flow keeps deteriorating despite profits.

Why It’s Serious

Signal of ‘creative’ accounting or catastrophic WCR management. Cash is reality, profit is just accounting construct. You can’t repay acquisition debt without cash.

·      Actions to Take

  • Calculate Free Cash Flow over 3 years: FCF = EBITDA – Taxes – Δ WCR – Capex
  • Analyze WCR evolution (value and days of revenue)
  • Verify consistency between cash flow change and profit
  • Request detailed cash flow statements
  • Identify possible accounting manipulations (overstocking, unprovisioned doubtful receivables)
  • Adjust valuation based on cash actually generated

 

Red Flag 9: Obsolete IT or Massive Technical Debt

The Symptom

IT systems over 10 years old, running on obsolete technologies, or internally developed without documentation. No modernization plan. Dependency on single vendor.

Why It’s Serious

Technical debt potentially representing 20-50% of acquisition price. Impossibility to scale or integrate with your systems. Risk of critical paralyzing failure. Massive hidden upgrade costs.

Actions to Take

  • Have IT audited by independent technical expert
  • Map architecture and identify obsolete technologies
  • Quantify technical debt (upgrade cost)
  • Assess compatibility with your systems (if integration planned)
  • Identify cybersecurity risks
  • Provision 5-15% of price for IT modernization
  • Plan 18-24 month migration

Red Flag 10: Degraded Social Climate

The Symptom

Recent history of strikes or labor movements. Turnover rate above 20-25% annually. Multiplication of employment tribunal cases. Complaints to labor inspection.

Why It’s Serious

Risk of major labor movement post-acquisition (change of control often trigger). Significant hidden costs (severance, stoppages, recruitment). Difficulty transforming organization. Degraded employer brand.

Actions to Take

  • Analyze 5-year labor relations history
  • Request minutes from employee representative meetings
  • List all employment tribunal cases (current and closed)
  • Assess climate via confidential manager interviews
  • Verify compensation gaps vs market (catch-up risk)
  • Provision ‘social peace’ costs (bonuses, raises)
  • Prepare Day 1 social communication plan

 

Conclusion: What to Do Facing a Red Flag?

The 3 Strategic Options

Option 1: Renegotiate price

Serious red flag justifies 15-40% discount depending on severity. Quantify financial impact and renegotiate.

Option 2: Require strengthened guarantees

Extended asset and liability warranty, conditional earn-out, price portion in escrow, seller clawback clause.

Option 3: Abandon the transaction

If 3+ major red flags or 1 insurmountable red flag (e.g., detected fraud), have courage to say no.

 

The Golden Rule

  • One isolated red flag = heightened vigilance
  • Two red flags = mandatory renegotiation
  • Three or more red flags = seriously reconsider the transaction

 

UPMYCO Detects Red Flags Before They Become Problems

Our M&A due diligence experts protect you from unpleasant surprises:

Flash audit (5-10 days): Rapid identification of major red flags for informed Go/No-Go decision

Complete due diligence (4-8 weeks): Exhaustive analysis of all aspects (financial, commercial, operational, legal, HR)

Risk quantification: Financial assessment of each red flag’s impact on valuation

Mitigation plan: Concrete actions to address or reduce identified risks

Get an initial free consultation about your acquisition project.

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