Leadership Due Diligence: The Missing Pillar in Every Deal File

Why $1 Trillion in Capital Is Being Deployed Through a Due Diligence Framework That Doesn't Measure the Person the Investment Depends On

Don L. Gaconnet, CSE III

Leadership_Due_Diligence_Missing_Pillar_Gaconnet_2026.pdf

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Founder & Principal Investigator, LifePillar Institute for Structural Identity Sciences

ORCID: 0009-0001-6174-8384 · SSRN Author ID: 7657314 DOI: 10.17605/OSF.IO/V8PYQ

DOI: 10.13140/RG.2.2.12020.72327

June 2026

Every due diligence framework in private equity has the same architecture. Financial diligence reads the math. Operational diligence reads the systems. Legal diligence reads the contracts. Commercial diligence reads the market.

Nothing reads the person.

The CEO or founder the deal thesis depends on — the human being who must carry the investment from close through hold through exit — passes through a behavioral interview, a personality questionnaire, a set of reference checks, and a brief conversation with the operating partner. Every one of these instruments reads what the executive presents. None of them measures what the executive's system is actually doing beneath the presentation.

This is not an oversight in a working system. It is a structural gap that the industry's own data says is producing measurable, quantifiable, and avoidable losses at scale.

The Numbers the Industry Published This Year

The data is not contested. It comes from the firms that lead the industry.

CEO departures hit 234 globally in 2025 — up 16% from 2024 and 21% above the eight-year average. The second consecutive record-breaking year (Russell Reynolds Associates, February 2026). Q1 2026 added another record: 77 new CEO appointments across the S&P 500, FTSE 100, and DAX 40 — the highest first quarter in at least eight years (Russell Reynolds Associates, April 2026).

65% of PE firms report CEO turnover during the holding period. Only 9% say they rarely replace CEOs (AlixPartners, 11th Annual PE Leadership Survey, March 2026). 83% of PE executives say unplanned CEO turnover lengthens holding periods. Nearly half say it reduces returns. CEO turnover spikes at year two.

External CEO hires in the S&P 500 nearly doubled — from 18% in 2024 to 33% in 2025 — pushing internal promotion rates below 70% for the first time in eight years (The Conference Board / Egon Zehnder, November 2025). One in three incoming CEOs is someone the board has never worked with.

Entry multiples reached a new high of 11.8x in 2025 (Woozle Research, April 2026). PE deal value hit $1.2 trillion — only the second time in history annual deal value crossed the trillion-dollar threshold (Cherry Bekaert / PitchBook, February 2026). $1 trillion in US dry powder sits under deployment pressure, with more than 40% available for two years or more — 15 percentage points higher than the five-year average (McKinsey Global Private Equity Report 2026).

The margin for error is at zero. Record capital is being deployed at record multiples into deals where one in three CEOs is new to the organization and more than half will be replaced within the first two years.

The Finding That Breaks the Existing Model

The critical data point in the 2025 turnover statistics is not the volume. It is the composition.

CEO successions at S&P 500 firms in the top three performance quartiles jumped from 7% in 2024 to 12% in 2025. Among bottom-quartile performers, the rate was only modestly higher at 14% (The Conference Board / Egon Zehnder, November 2025).

Top-performing CEOs are being replaced at nearly the same rate as underperforming CEOs.

This means the question has changed. The assessment question is no longer "is the CEO failing." The question is "can the CEO structurally carry what comes next." Performance does not answer that question. A CEO can deliver every KPI on the current plan and lack the structural capacity to carry the next phase — the post-acquisition integration, the operational scaling, the strategic pivot the deal thesis requires.

As Vantedge Search stated in February 2026: "CEO turnover in 2026 is being driven less by short-term performance issues and more by a structural shift in leadership expectations."

Heidrick & Struggles confirmed it in May 2026: more than a third of US companies still don't have a CEO with the capabilities needed for near-term success.

The industry is articulating a structural problem. The instruments the industry uses to assess that problem do not read structure.

What Every Assessment Tool in the Pipeline Actually Measures

Anirvan Sen, a veteran M&A advisor, wrote in April 2026 what practitioners have known for years: "Most leadership assessments done during M&A due diligence are theatre — too polite, too rushed, and too detached from what the deal actually needs to achieve."

Heidrick & Struggles — the firm that published the capability gap finding — has described its own historical approach as producing "intrusive, four-plus hour psychological interviews leading to unpleasant candidate experiences and very little data of predictive value."

These are not external criticisms. They are the industry's own practitioners describing the limitations of their own tools.

Every instrument currently in the leadership due diligence pipeline shares one structural dependency: the executive's self-report.

Personality assessments (Hogan, DISC, MBTI) are self-report questionnaires. The executive answers questions about themselves. The instrument processes those answers. The output reflects what the executive's system perceives about itself — not what the system is actually doing.

Behavioral interviews ask the executive to describe how they handled past situations. The executive narrates their own performance. The interviewer evaluates the narrative. The output reflects the executive's account of their own behavior — filtered through the executive's current perception of themselves.

360-degree feedback surveys ask colleagues to describe the executive. The colleagues have reorganized around the executive's presentation — their observations reflect the system that adapted to the leader, not the leader's structural state.

Reference checks evaluate past performance. Past performance under previous conditions does not predict structural capacity under future load. The CEO who built the company from $20M to $100M may not have the structural capacity to carry the post-acquisition integration from $100M to $500M. The reference confirms the track record. It does not measure what the track record costs the system carrying it.

The structural dependency is uniform across the competitive set. Korn Ferry, Heidrick & Struggles, Spencer Stuart, ghSMART, Russell Reynolds, Hogan — every firm reads the executive's presentation layer. The AI-enhanced platforms now entering the market read the same presentation layer with more sophisticated technology. Higher resolution does not change what is being measured.

Why the Executive Cannot Accurately Report Their Own Structural State

A 10,000-case Monte Carlo simulation published through the LifePillar Institute for Structural Identity Sciences (SSRN 7657314; DOI: 10.17605/OSF.IO/MVYZT) measured the gap between self-reported structural state and independently measured structural reality in a near-capacity population. The findings, with 95% confidence intervals:

81.4% (CI: 80.7–82.2%) misidentify the domain where their primary structural failure lives. Four out of five executives point to the wrong area of their life as the primary problem.

73.0% (CI: 72.1–73.9%) minimize the depth. Nearly three out of four place the problem closer to the surface than it actually resides.

61.1% (CI: 60.1–62.0%) are simultaneously wrong about both domain and depth.

The most consequential finding is inverse reliability: self-report accuracy degrades as structural severity increases. In the most severe categories, depth minimization exceeds 94%. The executives whose accurate assessment carries the highest stakes — the founders carrying the most load, the CEOs under the most post-acquisition pressure — are the executives whose self-report is most structurally wrong.

This is not a psychological weakness. It is a structural property of human systems under load. The Recursive Reliability Effect (Gaconnet, 2026; DOI: 10.17605/OSF.IO/MVYZT; Zenodo: 10.5281/zenodo.20099853) identifies the mechanism: the assessment function runs on the same substrate that is overloaded. The system that would need to accurately report its own state is the system that is failing. The mechanism preventing accurate self-detection is the same mechanism worsening the condition being assessed.

On May 28, 2026, Duncan et al. published a meta-analysis in JAMA Network Open confirming that standardized diagnostic interviews — the instruments the clinical and assessment fields treat as the gold standard — demonstrate only moderate test-retest reliability (κ = 0.69) across 57 studies, 26 countries, and 8,146 participants. The tool itself is inconsistent. The source providing data to the tool is unreliable. Two independent sources of error, operating simultaneously, in every assessment that begins from the interview.

The AlixPartners finding maps directly: 41% of PE executives say the quality of portfolio company senior leadership is a significant challenge — but only 13% of portfolio company leaders agree. A 28-point perception gap between the investor measuring from the outside and the executive reporting from the inside. The 81.4% domain mismatch rate is the structural explanation for why this gap exists and why it persists.

What Leadership Due Diligence Must Actually Measure

Sen concluded: "Deals do not fail because the model was wrong. They fail because the people charged with delivering the model could not or would not do so."

He is correct. And the structural implication of his observation has not been drawn: if the person is where the deal fails, the person is where the due diligence must measure. Not what the person says about themselves. Not what the person's colleagues observe about their presentation. Not what the person's references remember about their past performance. The person's actual structural state — measured independently, without depending on the person's self-report as primary input.

The forensic accountant does not ask the CFO to describe the books. The forensic accountant reads the books directly. The structural engineer does not ask the building manager whether the foundation is sound. The structural engineer reads the foundation directly. Every pillar of due diligence operates on independent measurement of the thing being assessed — except the human pillar. The human pillar asks the person to assess themselves and accepts the answer as primary data.

The structural assessment category that addresses this gap — cognitive due diligence — operates on a different principle than behavioral assessment. It does not begin from the executive's verbal narrative. It reads the structural state of the system independently. It measures the gap between what the executive reports and what the instrument finds. It produces a written structural engineering report that specifies where the structural load lives, what depth it operates at, and whether the system can carry what the deal thesis requires.

The report goes in the diligence file. Alongside the financial analysis. Alongside the operational assessment. Alongside the legal findings. The fifth pillar.

The assessment is brief. It does not require the executive's cooperation in the traditional sense — the executive participates but the executive's verbal performance is not the measurement. The output is not a personality profile, not a competency score, not a clinical diagnosis. It is an engineering-grade structural assessment of the person the capital depends on.

The Structural Question the Board Must Now Answer

Mark Gillett, Managing Director and Head of Value Creation at Silver Lake Partners, stated it directly to Russell Reynolds: "There are lots of examples of executives thinking they are doing a great job, but it isn't the plan the sponsor underwrote."

John Connaughton, Co-Managing Partner of Bain Capital, added: "You'd be amazed by the number of CEOs who don't ask for our work on the deal. It would be the first thing I would ask for."

Ted Billies, PhD, of AlixPartners, summarized the structural position: "Too many private equity firms are still reacting to leadership crises instead of preventing or anticipating them."

The board that deploys capital at 11.8x entry multiples into a deal where one in three incoming CEOs is externally hired, knowing that 65% of PE firms replace the CEO during the hold and that year two is the spike — that board has a structural question it must answer before the close, not after:

Can the person holding the investment together carry what we just bought?

The personality assessment cannot answer this question. The behavioral interview cannot answer this question. The 360-degree feedback cannot answer this question. The reference check cannot answer this question. Not because these tools are poorly designed, but because they all depend on a data source — the executive's self-report — that is wrong about the domain 81.4% of the time and wrong about the depth 73.0% of the time, and most wrong in exactly the cases where getting it right matters most.

Independent structural measurement of the person the capital depends on is the missing pillar in the due diligence framework. It is not a replacement for behavioral assessment. It is the structural layer that behavioral assessment does not reach.

Financial diligence reads the math. Operational diligence reads the systems. Legal diligence reads the contracts. Cognitive due diligence reads the person.

The fifth pillar belongs in the file before the check is written.

References

AlixPartners. (2026). 11th Annual PE Leadership Survey. March 2026.

Cherry Bekaert / PitchBook. (2026). PE deal value and market analysis. February 2026.

The Conference Board / Egon Zehnder / ESGAUGE / Semler Brossy. (2025). CEO Succession 2025. November 2025.

Duncan, L. J., Xie, W., et al. (2026). Test-retest reliability of standardized diagnostic interviews. JAMA Network Open. DOI: 10.1001/jamanetworkopen.2026.15039.

Gaconnet, D. L. (2026). The Recursive Reliability Effect. LifePillar Institute. SSRN 7657314. DOI: 10.17605/OSF.IO/MVYZT. Zenodo: 10.5281/zenodo.20099853.

Heidrick & Struggles. (2026). Route to the Top US 2026. May 2026.

McKinsey & Company. (2026). Global Private Equity Report 2026. February 2026.

Russell Reynolds Associates. (2026). Global CEO Turnover Index 2025. February 2026.

Russell Reynolds Associates. (2026). Q1 2026 CEO Appointments. April 2026.

Sen, A. (2026). The Five Things Leadership Due Diligence Must Assess in M&A. Medium. April 2026.

Vantedge Search. (2026). CEO turnover structural shift. February 2026.

Woozle Research. (2026). Entry multiples data. April 2026.

Don L. Gaconnet, CSE III

Cognitive Systems Engineer III

Founder & Principal Investigator, LifePillar Institute for Structural Identity Sciences

ORCID: 0009-0001-6174-8384 · SSRN: 7657314

Institute: lifepillarinstitute.org/research · Practice: dongaconnet.com/writings

Lake Geneva, Wisconsin · don@lifepillar.org

Copyright © Don L. Gaconnet, June 2026. All rights reserved. The assessment instrument, its operational architecture, scoring methodology, and all associated protocols are proprietary trade secrets of Don L. Gaconnet and the LifePillar Institute for Structural Identity Sciences.