Post-acquisition integration sequencing, ordered by where value is created and destroyed.
Integration playbooks open with branding, systems and synergy capture — because that is what playbooks have always opened with. The integration data says the window works differently: very little value is created in the first 100 days, but 73% of the value that underperforming deals eventually lose is already locked in by day 100, mostly as customer and key-person attrition.
The ledger reorders the window around where the risk actually sits: revenue protection first, decision rights across the seam second, cost synergies third, systems last. Every integration action is on the ledger with an owner and a week; every deferred action is on it too, with the reason. What is deliberately not done in the window is as explicit as what is.
Revenue protection as a named workstream: key customers contacted by name, key people retained by name, pricing discipline frozen. Nothing else outranks this.
Day 1–30One decision-rights ledger across the seam of the two organisations, published on day one and tested against real decisions by week six.
Day 1–45Cost synergies begin only when protection metrics hold; systems migration is scoped but deferred out of the window unless the deal case dies without it.
Day 30–100The ledger is maintained weekly against two numbers: customer retention and seam decision latency. They move before any synergy number does.
Mid-market acquisitions and mergers, from close through day 100.
Integration rescue, where a conventional plan has consumed the window and the attrition is arriving.
Deal diligence, read backwards: pricing the integration risk the target’s customer and management concentration implies.
Derived from the 28-integration sample and applied in every Markham integration since:
The Institute stewards the ledger and revises it after every tenth application review. Changes are versioned; superseded editions remain citable.
Cite as: Markham Institute, “The First 100 Days Ledger”, MKM-F-009, v1.0 (2024).