TL;DR
We estimate private equity firms commission about ~36,000 commercial due diligences (CDDs) each year. (We don't count CDDs for corporates, lenders and others in this report).
We can trace ~14,500 CDDs to 75 CDD-heavy strategy consulting firms. The remaining 21.5k CDDs are run in-house by the PE firms, by other advisory firms, or tagged as other work by our named firms.
Consultants do almost one million expert calls for those CDDs. Leading consulting firms use Inex One to run expert interviews faster, and build internal transcript libraries.
Also - this is fan fiction. We apply judgement to public data and there are most certainly errors. Let us know what we missed.
Strategy consulting is a big deal. More than 100,000 people work in the largest strategy shops alone. Over the past two decades, private equity has become a top customer segment. Those PE firms are in business to buy companies, tinker with them so they become (or at least look) better, and sell them onwards at a profit.
It has been a great ride:
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Most PE firms have lean teams, so they engage external consultants for lots of work that they can’t do in-house. It all starts with the coveted commercial due diligence (CDD) - understanding a company inside out, prior to potentially buying them.
For PE firms, understanding what you're looking at is central to making good deals (i.e. buying stuff you can sell onwards later at a higher price). And for strategy consultants, the CDD is the “gateway drug” to all kinds of lucrative downstream work (e.g. 100-day plans, PMIs, pricing, tech transformations, market entry work, and exit preps).
Expert interviews are important to both PE firms and consultants. But strategy consultants are the heaviest users of expert interviews by far. We estimate there are 36,000 CDDs each year for PE firms (and many more serving Corporates, lenders etc.), and we can attribute almost half of them to CDD-heavy consulting firms.
This article covers:
What I think of when I think of CDDs.
Top-down estimate, based on #PE deals.
Bottom-up estimate, based on what the consultants say (this is the juicy part!).
Bridging the two estimates.
Here we go:
What I think of when I think of CDDs
A commercial due diligence (CDD) is high-stakes fact finding: to understand the commercial prospects, opportunities and risks for a “target” company in the years ahead. In practice, that means understanding the industry value chain and players inside out - and it’s great if you could get us an answer by Friday.
There are two types of CDDs: buy-side (the “true CDD”) and vendor-side due diligence (“VDD”). The two jobs are similar, but differ in what access you have to the target company (a lot if you do their VDD; restricted in a CDD), and the outputs:
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For every company selling, there are multiple firms analyzing it - which makes CDDs far more common than VDDs. Going forward, I'll use "CDD" as the term for both.
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1. Who wants CDDs and why?
Anyone about to put serious money behind a deal, who wants to understand the commercial risks and upsides (CDD). And conversely, sellers who want to maximize the value from their asset (VDD).
Private Equity firms are the biggest buyers of CDDs. But even within PE, the need varies by stage (e.g. Platform deal vs. add-on), and type (buyout firms do more serious CDDs than VC, secondary or growth firms do).
Corporates use CDDs too, typically when acquiring their way into an adjacent market, or a new product/service category.
Lenders and credit funds sometimes run CDDs with external consultants, especially on larger deals.
For this study, we focus solely on Private Equity commercial due diligences. We exclude things like financial, tax, legal, or tech diligence, post-deal strategy, etc., because we’re ultimately interested in the market for expert networks - where CDDs are the main driver. If you’re more interested in the market for tax diligence - please call your doctor.
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PE firms follow standardized, repeatable processes, and are most likely to hire external consultants for CDDs. Conveniently, their deal activity is also public and easy to track.
2. Sizing the PE CDD market: Top-down
Firms like Mergermarket and S&P track all PE deals globally:
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A decade-long march upwards weathered the Covid crunch in 2020, and surged with low interest rates in 2021-22, before cooling down with macro uncertainty.
For simplicity, we assume all Exits (~2,200 last year) have a VDD attached, that no one does CDDs on Secondaries, while there are 4 CDDs for every Buyout deal that closes (~8,600 last year). The latter estimate is supported by a HBS survey and working paper (‘What do Private Equity firms say they do?’), showing about 1/4 CDDs proceed to closing.
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That sums up to ~36,000 CDDs (of which 2k were VDDs) for PE firms in 2025, for our top-down estimate. That's the amount of CDDs that should be done, given PE transaction volumes and habits. Applying the same estimates over time, CDD volumes would look like this:
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3. The bottom-up estimate (aka checking LinkedIn)
We checked what CDDs the ~75 main PE-focused strategy consulting firms say they do, and scaled that number to account for other vendors, independents etc.
While the CDD output from different firms might look similar, they serve different client segments, and in different situations. I'll be stepping on toes here for sure - it's inevitable when you simplify - but here's my attempt at mapping the CDD industry, tracking consulting firms with 20+ folks dedicated to PE and CDD work. Many firms would fit in multiple categories, but we've had to make this 2D. We kept both logos for recently merged firms. Check out their respective websites for more info on each firm. (And do let me know if we made any omissions or errors here, as we will update this chart over time).
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Did we miss your firm, or are you in the wrong bucket? Please let us know.
Strategy majors
These firms run the bulk of large-cap CDDs, and smaller deals too. They have teams specialized in multiple sectors. CDDs are a part of their overall strategy consulting operation, while also doing much downstream value creation work for PE, and non-PE work. We've got:
The MBB trio: Bain, BCG, and McKinsey.
Strategy Specialists: EY-Parthenon, PwC Strategy&, Kearney, Oliver Wyman, L.E.K. Consulting, Roland Berger, Monitor Deloitte, and Arthur D. Little.
Diligence specialists
These firms are the workhorses of mid-market deals. They offer CDDs as either the main service, or a large part of the business - alongside other strategy work. Many of them have a distinct spike in one or more sectors, regions or functional areas, while often serving multiple.
CDD Specialists (covering many industries & geos): OC&C Strategy Consultants, CIL Strategy Consultants, IGS, Advancy, Kaiser Associates (now with Sia Partners), and Stax (now with GrantThornton US).
Sector and Regional specialists:
Healthcare & Life Sciences: Simon-Kucher, ZS, Marwood, Inizio Ignite (fka Putnam), Trinity, Kx Advisors (now with BGBx), Candesic, Health Advances, Clearview, Mansfield Advisors, ISP Healthcare and others.
TMT: Zinnov, Altman Solon, Plural Strategy, Analysys Mason (incl. Telescope), Activate Consulting, PMP, and others.
Aerospace, Defense, Industrials: Renaissance, Archery, CSP Associates, Fairmont, Emerton, and others.
Other industries, and/or specific geographies: Alpha FMC, FMI, Cairneagle, Nomura Research Institute (NRI), Actionist, YCP Solidiance, CVA, Kéa & Partners, CA Strategy, Cicero, Arkwright, IGS, CMI Stratègies, Singular, Advention, Codex Partners, Satov, Cognosis, Sterling Associates, Fairgrove (now with GT UK), Fortlane, Pointe Advisory (now with Stout) and others.
Many of these firms were founded by alumni from larger firms. They could have built stellar careers within e.g. an MBB, but chose to set out on their own to run an independent and/or specialized high-end consulting firm.
Multi-disciplinary advisory firms
Certain firms run high-end CDDs alongside wider consulting practices (e.g. operations consulting, auditing, banking, market research or tech advisory). The respective CDD/strategy teams of these firms would independently fit in other buckets.
Value creation/restructuring specialists: Alvarez & Marsal, FTI Consulting, AlixPartners, and others.
Audit or finance specialists: KPMG, BDO, Accuracy, Grant Thornton (with Stax), Stout (with Pointe Advisory), and others.
Tech-led strategists: Accenture, Gartner Consulting, OMMAX, valantic, Ipsos, Sia (with Kaiser), North Highland, and others.
Smaller high-end firms, and independent ex-consultant pods also run CDDs, but their CDD volumes are difficult to track.
What the consultants tell us
Some firms announce all their CDDs, or the number of closed deals they supported (letting us infer the CDD count, incl. failed deals). Some post stuff on LinkedIn, in posts or bios. For others, we could infer the #CDDs from CDD consultants self-reporting on LinkedIn. We applied detective work + human judgment, like any consultant would.
In all, these firms say they do about ~14,500 CDDs per year. We get there by using the best available signal for each firm and sum across our tracked sample.
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If you're curious about the method, here's our methodology deepdive.
4. Bridging top-down and bottom-up
Our two estimates come out far apart. Top-down is 36k CDDs/year vs. bottom-up only 14.5k CDDs/year. That leaves more than half of CDDs unattributed to any consulting firm. It's frustrating, but also very interesting. 36,000 CDDs could & should be done, but less than half of them are served by named consulting firms.
The delta? That's opportunity for the bold.
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The >20,000 CDDs happening each year "off the radar" could be real work delivered by big consulting firms, but not reported as "CDDs". Or it's delivered by in-house diligence teams, an infinite tail of smaller CDD providers, or hybrid firms (banks, M&A advisory firms, audit firms, etc.).
Our bottom-up estimates are most certainly too low. Most firms we look at simply do not disclose CDD volumes at all. Some publish a number once and then leave it on their website for years without updating it. Others talk in broad terms like “transactions supported”. And even when we can track activity, plenty of real work never gets tagged neatly as “CDD” in public materials. Add regional differences and the long tail of smaller providers, and our bottom-up will inevitably come out low.
So where does that leave us? With the insight that there are loads of CDDs happening, and that any market sizing (or CDD for that matter) has room for a bit of guesstimates.
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One million expert calls for CDDs
Our 36,000 CDDs will use expert interviews differently. At Inex One, we've seen some CDDs run north of 100 expert interviews, while others kept it lean at 10.
If we assume the average CDD runs 25 expert interviews, that means our 36,000 CDDs consume 900,000 expert interviews each year. That, in turn, ties with our expert network market sizing, where we estimate that consultants spend $1.4 Bn on expert networks globally. It's fair to assume that PE-backed CDDs drive the bulk of that spend.
How do you manage all those expert calls?
Scheduling and running expert calls is intense. For every good call, there's a dozen experts to reject.
You juggle multiple vendors, screening questionnaires, scheduling conflicts, transcripts and so on. At scale, finding the right expert and managing calls is an operating system problem.
If your firm does CDDs, how you handle your expert interviews (and subsequent transcripts) is critical infrastructure.
With Inex One, you get to:
Run CDDs faster, streamlining all expert networks and surveys
Aggregate and reuse all call transcript insights, allowing you to move faster on the next project - and avoid spending resources on duplicating work.
Inex One is trusted by more than 8,000 clients globally across private equity, strategy consulting and corporate strategy. Try it out today!
