Most of the value in an acquisition is not created at signing. It is created — or quietly destroyed — in the months after closing. Here is what that looks like from the deal side.
Key takeaways
- Signing the SPA does not create value. It only creates the opportunity to create it.
- Value is rarely lost through one big mistake, but through dozens of small unresolved problems — starting with unclear governance on day one.
- Culture, synergies, the founder's role and the first 100 days decide whether the investment thesis is ever realised.
The day a deal closes, everyone celebrates. The buyer. The seller. The advisors. The lawyers.
And they are right to do so. Closing an M&A transaction is a real achievement. Months of work, analysis, negotiation, pressure. Many things could have gone wrong. They didn't.
But there is something nobody says out loud in that moment.
That the real work has just begun.
The dangerous illusion: believing the deal ends at the SPA
One of the most widespread — and most expensive — misconceptions in M&A is believing that the deal ends when the SPA is signed.
It doesn't end. It begins.
For months, sometimes years, buyers and sellers obsess over valuation, due diligence, warranties and price mechanisms. Advisors build models. Lawyers negotiate contracts. Investment committees debate risks and opportunities.
Then the deal closes. And then, almost without anyone saying it, the focus disappears.
The M&A team moves on to the next project. Advisors close their files. The company celebrates the closing. And integration is left in the hands of people who, in many cases, have been out of the process for months — or were never part of it at all.
Signing a deal does not create value. It only creates the opportunity to create it.
Where value is created — or destroyed
Value destruction in M&A rarely comes from a single dramatic mistake. It comes from dozens of small unresolved problems.
Decisions delayed because nobody knows who decides. Vague communication that generates rumours. Key talent that leaves before anyone notices. Priorities that clash because each company keeps operating as if the other didn't exist.
Each problem, in isolation, seems manageable. Together, they gradually erode exactly what justified the acquisition in the first place.
One of the earliest warning signs I've learned to identify is the absence of a clear governance framework from day one. Companies spend months analysing synergies and investment theses, but surprisingly little time defining — before closing — who is responsible for what, how decisions will be made and how progress will be measured.
When governance is unclear, value starts leaking almost immediately. (I wrote about the other side of this — the mistakes that destroy value before closing — in How value gets destroyed in M&A.)
Culture: the problem no model captures
Every acquisition model contains assumptions about revenue growth, cost savings and synergies. Very few contain assumptions about culture.
And yet culture is often one of the most decisive variables in determining the outcome.
Two companies can appear highly complementary on paper. The numbers work. The strategy makes sense. But if the organisations make decisions differently, recognise performance differently, or simply communicate differently — friction inevitably emerges.
Culture is not a "soft" issue. It is an execution issue. Because execution happens through people. And people operate within culture.
Peter Drucker said it better than anyone: "Culture eats strategy for breakfast."
Many of the integration failures I have witnessed began precisely where the spreadsheets stopped.
The synergy trap
Synergies are at the heart of many acquisition theses. Without them, many deals would never justify their price.
The problem is not identifying them. The problem is assuming they will happen on their own.
I have seen models where synergies seemed inevitable. Then reality arrived. Customers behaved differently than expected. Systems proved harder to integrate. Key people left. Implementation took longer. Costs were higher. Benefits came later. Sometimes much later.
Synergies are not impossible. But they are almost always harder and slower than planned. That is why execution matters infinitely more than estimation.
The founder dilemma
One of the most delicate moments in any post-acquisition integration involves the founder.
Before the transaction, the founder is the centre of gravity. The person who makes decisions. The person employees trust. The person who built the culture.
After the transaction, everything changes. Authority is shared. Governance evolves. Reporting lines become more formal. Decisions require more structure.
For many founders, this transition is significantly harder than they anticipated. Not because they lack capability, but because they are being asked to operate in an environment that is no longer the one they created. Some adapt very well. Others don't.
When the founder's future role has not been clearly defined before closing, tensions almost always emerge. Defining that role is not an operational detail. It is one of the most important decisions of the entire integration.
The first 100 days after closing
The first 100 days often determine the trajectory of the integration. Not because everything needs to be resolved, but because direction matters.
Employees watch closely. Customers pay attention. Investors monitor progress. The organisation wants answers: Who is making decisions? What is changing? What is staying the same? What are the priorities?
Uncertainty generates anxiety. Anxiety generates rumours. Rumours generate resistance.
The first 100 days are, above all, an exercise in clarity. People don't need every answer. But they need the confidence that someone has a plan.
Execute the thesis — and adapt it
Every acquisition is built around an investment thesis. A vision of how value will be created. A roadmap. A set of assumptions.
The challenge begins once execution starts. Because plans are developed under assumptions, and reality introduces facts.
Markets change. Customers react differently. Competitors respond. Opportunities emerge that weren't in the model. Risks appear that weren't either.
The objective is not blind adherence to the original plan. The objective is disciplined execution combined with intelligent adaptation. The best acquirers understand that difference: they learn to distinguish between defending the model and understanding the new reality.
A final thought
There is one lesson that becomes clearer after every deal I have been part of. The transaction is only a milestone. Not the destination.
The deal creates the possibility of generating value. Integration determines whether that value is ever realised.
Perhaps that is why so many experienced dealmakers eventually become obsessed with the post-closing period. Because when the excitement of the transaction fades, what remains is execution. And in business, as in life, execution is where intentions meet reality.
As the line often attributed to Thomas Edison puts it: "Vision without execution is hallucination."
In M&A, the deal is the vision. Integration is the execution. And that is where outcomes are ultimately decided.
Frequently asked questions
What is post-merger integration?
Post-merger integration is the process of combining two companies after an acquisition closes: governance, people, systems, culture and operations. It is the phase where the value promised in the investment thesis is either delivered or lost.
Why do so many acquisitions fail after closing?
Most failures come from many small unresolved issues rather than one big mistake: unclear decision rights, poor communication, loss of key talent, cultural friction and synergies that take longer and cost more than planned.
What should happen in the first 100 days after an acquisition?
The first 100 days should give the organisation clarity: who decides, what changes and what stays the same, and what the priorities are. People don't need every answer, but they need to see that there is a plan.
Integration, governance and synergies are covered in depth in the M&A Training Program and in my book Mergers & Acquisitions: Strategy, Execution, and Decision-Making.
First published in Inside Corporate Finance, my LinkedIn newsletter. Subscribe here.
