One Merger, Two Cultures: Why Merged Companies Stay Divided

The deal closed eighteen months ago. Two companies came together, and now they’re one company. So here’s the question: why do we still have two of everything? Two ways of logging a project, two tools that do the same job — and everyone knows which one is theirs. Two chat channels: the official combined one, where people are nice and polite and show up every day, and the old one, where the real conversations still happen. People are friendly in the joint meeting, then they go back to their own systems, their own habits, the people they’ve worked with for years. Most of us have a phrase for this point: ‘integration is taking a little longer than expected.’ I want to suggest it isn’t a process that’s going slow. I want to suggest the integration has probably stopped. Slow and stopped are two very different things: slow still gets there in the end; stopped never does. Today: why two companies can merge on paper and stay two in practice, long after they were expected to become one — and what we can build to change that. Let’s go.

Let’s talk about mergers — companies coming together, people from different cultures trying to integrate and work well. This usually isn’t a major catastrophe. Nobody’s arguing in the corridors; everybody’s polite, the work gets done, clients get served, the lights stay on. And underneath all of that, the two companies that were supposed to join into one are still running side by side. They haven’t fully integrated. You can see it every day. Watch who people ask when they get stuck — it’s nearly always someone from their own side, the person they’d have asked before the merger. Watch which system a task lands in when nobody says which one to use — usually the old one. Watch who gets pulled onto a difficult, high-stakes part of a project — usually someone from the same side, nearly every time.

And it’s not that people are being difficult, or consciously pushing against it. It’s habit. It’s history. As humans, we go with what’s comfortable, with what we know, so we get pulled towards the people we’ve worked with for years. None of that would matter much if it were fading — if the normal awkwardness of colleagues learning to work together were slowly sorting itself out. But here’s the problem: in a lot of mergers, it doesn’t fade. It hardens. The difference between the two teams becomes really obvious. The integration hasn’t happened, and the line between the two sides becomes a permanent part of how the place works — a line everyone can feel, but nobody’s talking about, because on the surface everything looks fine.

And this is where it costs real money. The stall doesn’t show up as a crisis; it shows up as a combined team that’s really still two teams with one name — running two sets of processes, meeting once a week, being cordial, but keeping everything separate. And the most expensive part shows up a year or two later, when the best people from the team that was acquired leave. Not because anyone treated them badly, but because they still feel they’re not really part of an integrated team — they still feel like the team that got acquired. Those people get lost. The deal doesn’t blow up; it just underdelivers. The savings and the growth in the plan never quite arrive. And because nothing is obviously broken, nobody can point and say ‘that’s what went wrong.’ There’s just a bottom-line number that should have been bigger, and a company that should have felt like one but is still, in reality, two. That’s the friction — not conflict, not chaos, just two capable groups of people quietly staying two capable groups of people, while all the benefits of merging slowly dissipate.

So why does this happen? It happens even in well-run mergers — the ones with a proper plan, a communications team, sometimes consultants brought in to bring the two sides together. There can be several reasons, but I’m going to focus on one today. Two researchers, Dora Lau and Keith Murnighan, described it back in the 1990s: fault lines. Let’s start with a normal team. People differ in all sorts of ways — their job, their age, how long they’ve been here, how they like to work — and normally those differences are all mixed up within the team. No two people line up exactly the same way, so there’s no clean line you can draw to split the team in two. That mix is exactly what keeps a team from splitting into two camps: everyone is a bit different from everyone else, so no single divide can take over.

A merger is different, because it isn’t one team with a mix of people in it. It’s two whole teams, from two different companies, pushed together and asked to become one — often to work even better than they did apart. And each team arrives complete: its own office, its own tools, its own way of working, its own people it has trusted for years. So they don’t blend into one coherent team. They sit side by side, two teams under a single name — and because each side already has everything it needs, nobody has much reason to reach across to the other. This is the strongest divide an organisation ever gets. It’s simply what a merger is, and it’s why ‘we’re one company now’ so often just isn’t true. It sounds great, but everybody can feel that fault line running down the middle, keeping the two teams apart.

Now the practical part — because it’s easy to hear ‘fault lines’ and think people are just being tribal or loyal, and that isn’t it. The people aren’t the problem; the setup is. When someone works closely, day to day, with a colleague from the other side, the divide quietly fades — those two people are bridging it, because they genuinely rely on each other. But here’s what catches leaders: when the divide is strong, if you don’t actively build something that bridges it, the fault line takes hold and hardens. Every month the two sides keep to their own tools, their own channels, their own people, the divide gets a little deeper, a little harder — until it stops feeling like a merger problem and just becomes ‘this is how things are around here.’ It’s not bad chemistry, it’s not resistance to change. It’s one unusually strong divide being left to get harder. And we tend to assume it’ll soften over time. The truth is, it rarely does.

So what can we do about it? First — and this is a little counterintuitive — we don’t weaken the divide by talking about it. Not with a value statement, not with a ‘better together’ campaign, not with another town hall. Those sound great, but great rhetoric doesn’t provide a solution. We weaken fault lines by building across them — by changing how the work is set up, not how people are feeling. Four moves, each of which changes something you actually control.

Move one: build mixed teams with a shared goal only both sides can reach. This is the most powerful move, so let’s start here. Put people from both sides on the same small team and give them a target they can’t hit on their own — one side’s reach plus the other side’s product, one side’s clients plus the other side’s skills. You create a team where each person is essential, and the people they need come from the other side. That creates a new ‘us’ — this team, with this goal. You haven’t given a speech about working together; you’ve just mixed the team and given them something real that forces them to rely on each other.

Move two: mix the everyday work, not just the leadership. This is a trap that catches good integrations. The leadership team is totally behind it — they’ve done the talking, they’re building new strategies together, they’re mixed and aligned at the top. And then they assume, ‘brilliant, we’re done; now it just filters down.’ But the fault line doesn’t live at the top. It lives in the daily work — in who sits together, who’s paired with whom on which job, who’s on the call getting it done. If the leaders are mixed and the day-to-day isn’t, the merger exists in the boardroom and nowhere else. So mix the pairs, mix the small teams — because it’s the everyday tasks, done together, that make a merger work, not the fact that leadership all know where they’re going. That matters too, but success or failure happens with the everyday people doing the everyday work.

Move three: make working across the line the easy option. Ask an honest question about your own systems: if someone wants to get something done today, is the quickest way the combined way, or the old way? If the old system or channel is faster, people will use it — not out of loyalty, but because it’s less friction: ‘I know how to do it.’ If the new way is harder, more steps, more cognitive load, they’ll revert to what they know. Every time the old way is the easier way, you’re quietly rewarding people for staying apart. So it’s not about willpower, it’s about design. Make the combined way the quick, easy one, and let the old way slowly become the slower one — and people will naturally flow toward what brings both sides together. You’re not asking people to do the harder thing because it’s right; you’re making the easy thing the one that joins the two sides.

And move four: give it more time than the plan said — and spend that time building. Bringing two companies together takes longer than a plan usually admits, and that’s fine. Give it eighteen months, give it two years. But time on its own won’t make the fault line fade. If you spend those months waiting for the two cultures to blend by themselves, you’ll end up with a divide that’s harder to break, because the longer it’s in place, the deeper it sets. So spend that time building: intentional team-building, deliberate mixing, bringing people together so they use each other’s skills — not because they’re told to, but because that’s how they hit the targets they need to hit.

Notice that none of these four moves asks anyone to feel differently, to be more open, or to try harder to get along — because that doesn’t work. Each of them changes something you control: who’s on the team, who’s paired with whom, which way is the easy way, and how much extra time is spent building. You don’t talk a divide away; it never goes with words. You build across the fault lines, intentionally, and you enable people to rely on each other across them.

So, the one thing. If you take one thing from this episode, take this: we don’t get rid of a fault line by pretending it isn’t there, or by talking about it. We weaken a fault line by building things that cross it. Every ‘we’re one company now’ is just words — people can feel the line underneath, so it bounces off. But every mixed team, every shared job, every system that only works well when both sides use it — that’s what crosses the line. And crossing the line is the only thing that actually works. So stop announcing that two teams are now one, and start building across the divide. That’s the easiest way to turn two companies into one.

If this is a live issue for your team right now, that’s exactly the kind of thing I work through one-to-one with leaders — through advisory, coaching and workshops. You can find out more at brendanthomasquinn.com, and you can also find me on LinkedIn.