What Operational Due Diligence Actually Catches (That Financial Due Diligence Misses)

Financial due diligence answers one question well: are the numbers real? Quality of earnings, normalized EBITDA, working capital trends, tax exposure — a rigorous financial workstream will tell a buyer whether the historical financials can be trusted.

It will not tell a buyer whether the business can still produce those numbers a year from now.

That's a different question, and it belongs to operational due diligence — reviewing supply chain resilience, customer relationship quality, contract terms, and manufacturing footprint under the assumption that ownership, pressure, and priorities are about to change. Most standard diligence processes underweight it, largely because it's harder to compress into a data room checklist than a quality-of-earnings report. The gap that creates shows up consistently in our work with private equity clients running compressed deal timelines.

A real example from an active acquisition pipeline

We were recently engaged by a middle-market private equity firm managing a 25-company, $1B+ portfolio, in the middle of an aggressive multi-target acquisition streak. The firm's deal team had strong financial diligence experience, but lacked the operational bandwidth and industry-specific expertise to fully vet targets on a compressed timeline while running several deals in parallel.

We stood up a rapid-response operational assessment team to evaluate each target business, quantifying risk and opportunity to directly inform go/no-go decisions and 100-day post-close work plans. In that engagement, our team identified:

1. A target acquisition that was actively losing its largest customer — before close
2. A target locked into a long-term, unprofitable supply contract
3. Significant additional costs and risk tied to a target's proposed manufacturing move to China
4. More than $1M in cost-savings synergies and over $2M in obsolete inventory that the financial audit had not caught

None of these findings would have surfaced in a standard quality-of-earnings review. Each one came from operators asking operational questions — walking the supply chain, reading contracts for what happens after a change of control, and testing whether reported inventory matched what was actually usable.

Why this keeps happening across the market

Our experience on this engagement isn't an outlier. It reflects a pattern the broader deal community is increasingly naming directly. Alvarez & Marsal's most recent diligence research notes that buyers "now demand equally rigorous operational assessment alongside commercial and financial analysis — evaluating cost structures, workforce capability, technology readiness and leadership capacity to execute on fast-moving growth strategies" (Alvarez & Marsal, Due Diligence in Adapting to Volatility, 2026) — a direct acknowledgment that financial and operational diligence are no longer treated as interchangeable.

Wharton's research on deal failure points to the same structural gap: standard diligence processes frequently accept seller forecasts without independent verification and miss operational and technology risk that isn't visible in a data room (Wharton, Why Many M&A Deals Fail and How to Beat the Odds).

Customer concentration is a particularly sharp example, and it's exactly what our team caught in the case above. Industry commentary tracking PE deal outcomes has estimated that customer-related surprises derail roughly 1 in 11 PE deals outright and materially affect another 1 in 5 (LinkedIn, The Real Cost of Customer Surprises in Private Equity) — directionally consistent with what we see in the field, even though it's a single practitioner's estimate rather than a formal industry study. A standard financial diligence report will list a target's top 10 customers and their revenue share. It rarely tests whether those relationships are actually secure.

What a rigorous operational review actually tests

In our experience, a real operational due diligence process goes beyond the org chart and the customer list on the data room index. It tests:

1. Customer relationship durability — not just concentration percentages, but whether key accounts are actually retained, and under what terms
2. Contract exposure — whether existing supply or customer agreements survive a change of control on acceptable terms, or convert into liabilities the moment ownership changes
3. Manufacturing and network resilience — whether proposed facility moves, supplier consolidations, or geographic shifts introduce cost and risk that hasn't been priced into the deal
4. Inventory and working capital reality — whether reported inventory is genuinely usable, or whether obsolete stock is inflating the balance sheet the financial audit relied on

Each of these is answerable before close, if the diligence process is built to ask the question. Each one, left unanswered, becomes a first-100-days surprise instead of a negotiated adjustment.

What this means for sponsors and operating partners

For sponsors, the practical implication is straightforward: operational findings belong in the same room as financial findings before an investment committee vote, not as a post-close workstream. A go/no-go decision made without them is a decision made on incomplete information, regardless of how clean the quality-of-earnings report looks.

For operating partners inheriting a portfolio company, operational diligence findings — when done well — become the first draft of the 100-day plan rather than a fresh discovery exercise. The synergies and risks are already quantified; the work is executing against them, not finding them for the first time under pressure.

For CFOs running a competitive process on the sell side, this cuts the other way: expect operational scrutiny that goes well past the data room, and get ahead of the questions a rigorous buyer's ops team will ask about customer durability, contract terms, and inventory quality before they ask them in diligence.

A closing question for the next deal

The next time a synergy case or a go/no-go decision rests entirely on a quality-of-earnings report, the question worth asking isn't whether the financials have been verified. It's whether anyone has tested if the business can still produce those numbers once ownership changes.

We built our operational due diligence practice to answer that question on compressed timelines, without slowing down the deal process. If you're running diligence on an active target and want a second set of operational eyes before your investment committee vote, we'd welcome the conversation.

Explore our M&A Advisory & Synergy Value Creation practice

Operational due diligence is the entry point to our five-phase diligence-to-execution model. See the full framework — and how findings carry directly into post-close workflows — on our M&A Advisory & Synergy Value Creation service page. For the broader thesis on redesigning diligence so AI shows up in EBITDA, see From AI Theatre to EBITDA: A Better Model for Operational Due Diligence in M&A.

Sources

• Alvarez & Marsal, Due Diligence in Adapting to Volatility (2026 Diligence Report)
• Wharton, Why Many M&A Deals Fail and How to Beat the Odds
• Daniel Grainger, The Real Cost of Customer Surprises in Private Equity (LinkedIn — practitioner estimate, cited as directional industry commentary, not a formal study)