The First 100 Days: A Practical Guide to Merger Integration

The CFO hands you a one-page document. It lists the metrics that will define whether this deal succeeded. Revenue retention. Cost synergies. Time to standalone operations. Customer satisfaction scores at 90 days. Everything you do for the next 100 days should trace back to this page.

Day 0: Establish Program Structure

Before the deal closes, stand up an Integration Management Office with unified processes and centralized documentation. Finance sits inside the core planning team—not running a parallel track. Every workstream gets a charter that connects directly to value creation. Decisions get logged. Risks get owners.

We worked with a life sciences company that obsessed over the basics first: making sure everyone could log in on Day 1, that payroll would process correctly, that customers knew who to call. Not glamorous. But it built confidence that carried through harder decisions later.

Days 1–30: Maintain Stakeholder Confidence

Silence erodes credibility faster than bad news. Reliability is the first thing that matters.

• Key customers get direct outreach from identified leaders
• Town halls happen weekly with honest answers (including “we don’t know yet”)
• Operations teams get listening sessions, not just announcements
• Weekly summaries document decisions made and next steps planned

During a data analytics carve-out, we positioned program team members alongside customer support. Within 72 hours, patterns emerged. The same questions kept surfacing. We built unified answers. Customer attrition risks dropped because information gaps closed.

Days 31–60: Define Operating Model

Organizational design isn’t about drawing boxes. It’s about deciding who decides.

Key questions to resolve:

• Who sets pricing? Who approves exceptions?
• Who prioritizes the product roadmap?
• Where does information live, and who maintains it?
• What’s the span of control for frontline managers?
• How do cross-functional decisions get made?

Build RACI matrices that people actually reference. Document governance structures that enable “no” decisions as clearly as “yes” decisions.

A global SAP initiative we supported chose to go “best-of-both” in Finance while fully absorbing the acquiree’s Procurement function. The choice wasn’t ideological—it was practical, based on sequencing and talent availability.

Days 61–100: Demonstrate Measurable Progress

By now, you need tangible evidence, not promises.

• Dashboards show value realization—not just project completion
• Customer-facing improvements are visible
• Managers can explain what’s different without slides
• System go-lives happen through structured command centers, not last-minute heroics

The first 100 days don’t have to be dramatic. They have to be deliberate. People keep their jobs. Paychecks arrive on time. Customers see continuity. And the thesis starts showing up in the numbers.

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If you’re approaching a merger or acquisition and want to discuss integration planning, reach out. We’ve supported transactions from $50M to $3.5B across industries.