Over the past few weeks I’ve been watching a series of acquisitions in Czech business. Smaller, honestly built companies are merging with bigger players, founders stay on board as co-owners, and both sides talk about shared values and joint growth. On paper it looks like a textbook example of healthy consolidation, but post-acquisition integration is what decides whether the investment pays off. In practice, that’s exactly the moment that decides whether an acquisition will be a case study of successful growth five years from now, or a quiet example of wasted potential.
Post-Acquisition Integration: Why Companies Underestimate It
I’ve spent twenty years around running companies, and I hold one firm view on integrations: we systematically underestimate them. Companies spend months on due diligence, lawyers fine-tune the contract down to the last clause, advisors calculate synergies to the decimal point — and then the integration itself is expected to be handled by management that’s never done anything like it before and is also fully occupied running day-to-day operations.
Founders are particularly vulnerable here. They’ve spent their entire professional lives building one company, one team, one culture. Suddenly, after the acquisition, they have to align their own processes with the new owner’s, explain to people why they’re suddenly reporting somewhere else, and at the same time keep up the morale of a team afraid that the family business is about to become just another line item in a portfolio. That isn’t failure — it’s simply a different discipline from the one they’ve practiced so far. This is exactly the phase where an experienced interim HR manager can carry a lot of the weight, keeping communication with the team going and easing fears about the change in company culture.
Most M&A studies agree on one number that hasn’t changed in years: a majority of acquisitions fail to reach their expected value, and the main cause is usually integration, not the deal price or the due diligence. Companies are good at finding the right acquisition. They’re good at paying for it. What they lack is capacity — someone who has the time to focus on the first three to six months, when the real outcome gets decided.
Post-Acquisition Integration: Who Should Lead It
This is exactly where there’s room for an interim manager to lead the post-acquisition integration. Not as a firefighter who steps in once the integration is already burning, but as preventive reinforcement for leadership from day one. An experienced interim CEO who has been through a similar process repeatedly can name cultural and process risks before they become problems, align reporting and decision-making authority between both sides, and, once the mandate is fulfilled, hand everything over to a trained leadership team. No politics, no fights over positions, with a clearly defined end to the engagement.
In practice, that means one simple thing: the integration mandate should be ready on the day the contract is signed, not three months later once the first conflicts between teams start. Who decides what, who reports to whom, what the first three priorities are for the first ninety days — all of that should be clear before the first email about “shared values” is even sent.
The First Hundred Days of Integration
I’ve found it works well to split the first hundred days of integration into three phases: listening and mapping risks in the first two weeks, fast interventions wherever key people or customers are at risk of leaving, and only then systemic changes to processes and reporting. Companies that skip this sequence and go straight to changing systems usually run into resistance they brought on themselves — and the integration then drags on far longer than it needed to.
Czech companies still mostly see an interim manager as an emergency solution for a crisis, not as a standard tool for post-acquisition integration. The data backs that up: according to Harvard Business Review, as many as 70 to 90 percent of acquisitions fail to reach their goal, and post-acquisition integration is the most commonly cited reason. The most successful acquisitions and expansions I’ve seen up close all had one thing in common — integration was led from day one by someone with real experience in it. How many acquisitions around you would have turned out differently if they’d had clearly led integration from the start? Usually the answer only becomes clear years later — and it tends to be an expensive lesson.
