M&A Execution: Where Deals Succeed or Fail After Signing

Deal teams get judged on getting to signature. Operating teams get judged on what happens for the eighteen months after it — and that's usually where the value modelled in the deal thesis is either captured or quietly lost. We run the operational side of acquisitions and mergers, and the pattern is consistent: the deals that underperform rarely fail because the thesis was wrong. They fail because integration was under-resourced relative to the complexity it turned out to have.

1. Synergies on a slide aren't synergies until someone owns capturing them

Cost synergies, cross-sell opportunities, combined procurement leverage — these get modelled in detail during diligence and then, too often, handed to whichever team happens to be free post-close. Each synergy line needs a named owner, a timeline and a tracking mechanism from day one, or it quietly evaporates over the following two quarters.

2. Sequence the integration — don't run everything in parallel

The instinct after close is to integrate everything at once: systems, teams, brand, processes. In practice, this overwhelms both organisations simultaneously and stalls the operational work that actually generates the deal's return. A sequenced plan — critical systems first, culture and process second, full integration over a defined window — nearly always outperforms a parallel "big bang" approach.

• First 30 days: stabilise — payroll, customer continuity, key supplier relationships, leadership clarity.
• 30–120 days: integrate the systems and processes that unlock the modelled synergies.
• 120 days+: full operational and cultural integration, measured against the original deal thesis.

3. Coordinate finance and delivery teams explicitly — don't assume they will

Finance is tracking the deal's financial performance against the model. The delivery team is running the actual operational integration. When these two don't talk on a fixed cadence, finance discovers underperformance months after it started, instead of catching it in week three.

A deal thesis is a forecast of what the combined entity can become. Execution is the only thing that turns that forecast into an actual balance sheet.

4. Protect the acquired team's operational knowledge before it walks out the door

Key-person risk spikes right after an acquisition, exactly when institutional knowledge about customers, processes and supplier relationships is most needed. Identifying and retaining — or deliberately transferring — that knowledge in the first 90 days is cheaper than losing it and rebuilding it later.

The bottom line

The diligence process answers "should we do this deal." Execution answers "did the deal actually work" — and it's decided by resourcing, sequencing and coordination choices made in the months right after signature, not by anything in the data room.