Definition
Post-Merger Integration (PMI)
The execution programme that delivers the value-creation plan after the deal closes.
PMI runs Day 1 readiness, the 100-day plan, and the multi-year integration roadmap in parallel. Standard workstreams: legal entity, finance, technology, people, commercial, and culture. The number consistently quoted in industry research — most deals fail to deliver the deal-case synergies — is largely a story about under-resourced PMI rather than overstated synergies.
See also
Read further in The Guide
The Day 1 Readiness Plan
What absolutely has to work on Day 1 of an acquisition — comms, payroll, access, customer contracts — and what can wait until Week 2.
Building the 100-Day Integration Plan
How to scope, sequence, and govern the first 100 days post-close so that integration momentum survives the inevitable surprises.