Integrating two companies is conceptually simple to describe and genuinely difficult to execute. The steps below are the same ones Stonehill follows when we run post-merger integration for private equity firms and corporate acquirers. We're laying them out in full, because understanding the process is the easy part. Where it gets hard is doing all five steps at once, with full objectivity, while the business keeps running underneath you.

Step 1: Translate the Deal Thesis Into an Integration Plan

Before any work starts, someone needs to convert the reasons the deal was done - cost synergies, revenue synergies, new capabilities, market access - into a plan with owners, timelines, and numbers attached.

This sounds straightforward. In practice, it's where many integrations quietly go wrong from day one. The people who negotiated the deal aren't always the people running integration, and a lot gets lost in that handoff. The synergy figures that looked clean in a deal model often don't map cleanly onto real org charts, real systems, and real people.

Where this typically breaks down internally: Whoever inherits this translation job usually has a full-time role already. Integration planning becomes the thing they do in the margins of their actual job - and a deal thesis that doesn't get rigorously translated into an executable plan rarely gets delivered later, no matter how good the original model was.

Step 2: Stand Up an Integration Management Office (IMO)

The IMO is the team that owns coordination across every workstream - strategy, operations, systems, culture - and has the authority to make decisions or escalate them fast.

Without a real IMO, integration becomes five separate initiatives run by five separate leaders, each with their own priorities and none with visibility into the others. Conflicts surface late, usually after they've already cost time or money.

Where this typically breaks down internally: An IMO only works if it has real authority across departments - which means someone needs to lead it who isn't already the head of Sales, or Finance, or Ops, with their own team and incentives to protect. Most companies don't have a neutral, cross-functional leader sitting around with bandwidth to take this on.

Step 3: Design the Combined Operating Model

This step decides who runs what in the new organization - org structure, reporting lines, decision rights, and governance.

Get this wrong, or leave it ambiguous too long, and everything downstream slows down. Teams won't commit to new processes if they don't know who their leader will be in three months.

Where this typically breaks down internally: Operating model decisions are political. They involve people's jobs, titles, and authority - often people who were senior leaders at the company that got acquired. Internal teams designing this themselves are rarely seen as neutral, and decisions made (or delayed) under that perception create resentment that outlasts the integration itself.

Step 4: Align Systems and Operations

This is the unglamorous, high-risk work: reconciling ERP systems, CRMs, reporting tools, and operational processes that two companies built independently and never expected to merge.

Done well, the combined business gets a single source of truth fast. Done poorly, data gets lost, reporting breaks, and customer-facing teams can't see what they need to do their jobs.

Where this typically breaks down internally: Internal IT and ops teams already have a full workload running the existing business. Systems integration competes directly with that workload, and it usually loses - which is how companies end up running two disconnected systems for a year longer than planned, quietly bleeding efficiency the whole time.

Step 5: Integrate Leadership and Culture

This step aligns how the two organizations communicate, make decisions, and work - and actively manages retention of the people whose departure would hurt the business most.

Culture differences are usually invisible on a deal model and very visible six months after close, once frustration has had time to build.

Where this typically breaks down internally: Nobody inside either organization is neutral on culture. The acquiring company tends to assume its way of doing things is simply "correct," and the acquired company's leaders are often too anxious about their own roles to push back, even when they should. Real cultural integration takes someone with no stake in either side's status quo.

The Pattern Across All Five Steps

Notice what repeats in every "where this breaks down" section above: bandwidth, authority, and objectivity. Internal teams are short on at least one of those in almost every integration - often all three.

That's not a knock on internal teams. It's the actual structural problem with integration: the people best positioned to know the business are the same people who are too busy running it, too embedded in its politics, or too close to its culture to lead a neutral, full-time integration effort on top of their day job.

What This Means in Practice

This is exactly the gap Stonehill exists to close. We run post-merger integration as a structured, full-time engagement - leading the IMO, designing the operating model, aligning systems, and managing cultural integration - so your leadership team can stay focused on running the business instead of splitting attention across both.

Studies show 70% to 90% of acquisitions fail to deliver their intended value, almost always because of what happens (or doesn't happen) in integration, not the deal itself. The five steps above are the right steps. The question worth asking honestly is whether your team has the bandwidth, authority, and objectivity to execute all five at once, on top of everything else already on their plate.

Talk to our team about running point on your integration, or see how the first 100 days play out with our post-merger integration checklist.