Part 1 of a four-part series on integration, value destruction, AI, and leadership
(You can read the related articles at the end of this post)
Over the last year I have been deliberately meeting firms and employees several years after their acquisitions. In most cases two to three years after full integration, sometimes longer.
These are not cold conversations. My firm has often worked with these organisations from technology due diligence through to post-merger integration. We know the transaction logic, the operating assumptions, and the people involved. What we rarely do in M&A is return once the deal has fully transitioned into business as usual and ask a more uncomfortable question.
How did it actually turn out?
Those conversations have been some of the most useful work I have with customers done in years.
The outcome is far more binary than expected
What becomes clear very quickly is that post-acquisition outcomes are not nuanced.
They are binary.
Either the deal worked and most people are broadly happy, or it didn’t and the issues are still present years later. There is very little middle ground.
When acquisitions work, the signals are obvious. The P&L performs broadly as expected. Systems are described as enabling rather than obstructive. And people talk about growth, opportunity, and career progression.
When acquisitions do not work, the signals are equally obvious. Conversations become guarded. Language shifts to “them and us”. Systems are described as a daily frustration. And morale never quite recovers.
What is striking is how early these trajectories are set, and how persistent they are over time.
Why looking back matters more than post-deal reviews
Most integration reviews happen too early. Thirty, sixty, or ninety days post-close. At that point people are still optimistic, still adjusting, and still invested in making things work.
The conversations I am having now are very different.
People are relaxed. Careers have progressed or stalled. Systems have settled. The organisation has moved on. And with that distance comes honesty.
Patterns emerge very quickly.
In successful integrations, people feel part of something larger without feeling diminished. They describe having more structure, better support, and clearer progression. Many have moved into roles that simply did not exist in their former SMB.
In unsuccessful integrations, people describe frustration rather than anger. The problems are not acute enough to trigger intervention, but persistent enough to erode trust and performance year after year.
This is where value destruction really lives.
The industry already knows integration is the problem
None of this should be surprising.
McKinsey & Company has consistently found that a large proportion of M&A transactions fail to deliver their expected value, not because the strategic rationale was wrong, but because integration execution proves more complex than anticipated. McKinsey’s research shows that integration related issues such as organisational friction, operating model disruption, and cultural misalignment are among the most common causes of post-close underperformance, with estimates suggesting that around 70 percent of deals do not fully achieve their intended synergies.
Bain & Company reaches similar conclusions. Bain’s work on M&A integration highlights cultural friction, leadership alignment, and operating model fit as some of the strongest predictors of deal success or failure. Despite this, Bain notes that these factors are frequently underweighted during deal planning in favour of financial structure and transaction mechanics.
Harvard Business Review has repeatedly documented that acquirers tend to underestimate how long it takes for organisations to adapt to new governance, systems, and expectations. HBR articles analysing decades of M&A outcomes consistently point to post-deal integration challenges, rather than valuation or deal strategy, as the primary reason transactions fail to achieve their intended outcomes, with failure rates often cited between 70 and 90 percent.
What is missing from much of this research, however, is the long view. How these decisions feel to the people living with them several years later, once systems have settled, leadership has changed, and the initial optimism has faded.
That is where the most useful lessons begin to emerge.
(References below)
Three themes keep repeating
Across all of these post-acquisition conversations, three themes come up repeatedly.
First, value destruction. Not dramatic collapse, but slow erosion caused by loss of speed, loss of clarity, and poorly designed integration decisions. This is the focus of Blog 2 in this series.
Second, artificial intelligence. Smaller companies are often far more advanced in their day-to-day use of AI than their acquirers realise, making integration significantly more complex than expected. This is explored in Blog 3.
Third, leadership. The difference between integrations that create careers and those that create resentment almost always comes down to leadership decisions made early and left unchallenged. This is the focus of Blog 4.
Why this matters heading into 2026
As we move towards 2026, integrations are becoming harder, not easier.
Targets are more operationally mature.
Technology stacks are more interconnected.
AI is embedded into daily workflows.
And remote working has reduced the informal integration that used to happen naturally.
In this environment, hoping that things will “settle down” is no longer a strategy.
The organisations that succeed are not those with the most detailed PMI playbooks, but those that take integration design seriously as a strategic discipline rather than an executional afterthought.
This four-part series is a reflection on what actually happens after the deal. Not at signing, not at Day 100, but years later when the outcome is no longer theoretical.
In the next blog, I will look at value destruction, and why well-run businesses so often go backwards after acquisition even when everyone involved is competent and well intentioned.
References
- McKinsey & Company, Why Managing Culture Is Critical for Value Creation in M&A
https://www.mckinsey.com/capabilities/m-and-a/our-insights/why-managing-culture-is-critical-for-value-creation-in-m-and-a - McKinsey & Company, Merger Management Compendium
https://www.mckinsey.com/capabilities/people-and-organizational-performance/our-insights/merger-management-compendium - Bain & Company, The Cultural Integration Challenge in M&A
https://www.bain.com/insights/cultural-integration-m-and-a-report-2023/ - Harvard Business Review, Don’t Make This Common M&A Mistake
https://hbr.org/2020/03/dont-make-this-common-ma-mistake
