The People Side of M&A Part 4: Post-Close, Now What? Immediate Culture Moves That Set the Tone

You've closed the deal.

The data rooms are behind you, the press release is live, and the vision is clear. But for employees, the questions are just beginning.

What’s changing? Will I still have a job? Whose way of working will win out? Is this still a place where I belong?

In the days and weeks following a merger or acquisition, culture shifts from abstract risk to lived reality. And how leadership handles this moment often defines the trajectory of integration, and whether or not the deal thesis gets delivered.

Here’s how we guide our clients through the first 90 days post-close to align teams and build trust.

Step 1: Define the Cultural Integration Mandate

Before you can align people, you need to align leadership. That means defining:

• Which behaviors and norms need to stay the same?

• Which ones need to evolve to support the new structure?

• How will you communicate that shift with clarity and credibility?

Cultural integration shouldn’t be a vague goal like “preserve what’s good.” It should be framed like any other strategic initiative: specific, sequenced, and owned.

At Rhizome, we often help teams draft a Culture Integration Charter — a short, actionable document that lays out what will change, what won’t, and how success will be measured.

Step 2: Activate Leadership Alignment

Employees take their cues from leadership. If senior teams from both sides are aligned, present, and modeling the desired behaviors, the broader team will follow. If they’re out of sync, your integration will stall, no matter how strong your comms plan is.

Key actions:

• Host a joint leadership offsite to align on operating cadence, communication protocols, and decision-making norms

• Assign cross-company pairings or shadowing to speed trust-building and shared context

• Define leadership team rituals (weekly touchpoints, shared Slack channels, cross-functional steering groups)

Integration is not just about structure. It’s about operating as one team and that has to start at the top.

Step 3: Address the “Invisible Questions” Early

One of the biggest mistakes companies make post-close is communicating only the technical changes: reporting lines, role clarity, benefits, etc.

Those are necessary, but not sufficient.

Employees are asking emotional questions, too:

• Am I valued in this new structure?

• Will the parts of the culture I loved still exist?

• Who do I go to for guidance now?

You don’t have to have all the answers. But you do need to name the uncertainty, give people a safe way to ask questions, and offer transparency wherever possible.

Tactics that work:

• Live Q&As with leadership (not just top-down all-hands)

• Feedback channels that are anonymous and actually acted on

• Change narrative documents — internal FAQs that go beyond logistics to explain why decisions were made

Step 4: Signal Early Wins and Shared Ownership

Post-close fatigue is real. After the deal announcement, teams often wait to see whether this integration will be “more of the same” or something different.

That’s why it’s critical to create and celebrate early wins that:

• Reflect the new vision

• Involve cross-company collaboration

• Are communicated widely and meaningfully

You’re not just showing progress, you’re shaping the narrative. And you’re reinforcing the idea that this isn’t a takeover. It’s a shared transformation.

Step 5: Don’t Over-Index on Speed Invest in Trust

We often hear this tension from clients: “We want to move fast, but we don’t want to lose people.”

The truth? If you move without trust, you lose speed anyway. Rework piles up. Leaders hesitate. Engagement drops.

Instead of racing through integration, focus on building predictability:

• Do what you say you’ll do

• Follow up on questions

• Keep messaging consistent across levels and functions

Trust doesn’t require perfection. But it does require follow-through.

Final Thoughts

The close date isn’t the finish line, it’s the start of the real work.

In the first 90 days, culture becomes visible. People decide whether they’re in or out. Leaders set the tone for whether this is integration by decree or alignment by design.

At Rhizome HR, we believe post-close planning should treat culture like a core workstream, not a soft variable.

In our next (and final) post in this series, we’ll explore how to keep a pulse on cultural health long after the integration team winds down

and how to build accountability for the people side of value creation.