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What M&A Diligence Can't Write Down
No plan survives first contact with the enemy. That’s the familiar version of a line from Helmuth von Moltke. In mergers and acquisitions there is no enemy, but the point still holds: no plan survives its own execution intact.
Much of the work before an acquisition closes is building a plan. Months of diligence go into the data room: the financials, the contracts, the customer concentration, the tech stack, the org chart. The integration plan gets written from all of it, and it is usually a good plan. Then the deal closes, two living organizations meet for the first time, and the plan starts coming apart.
It isn’t because diligence was sloppy. Some of the risks that decide the first year after close are characteristics, not facts. They’re ill-defined to begin with, so nobody can write them down, and they never make it into the data room.
That doesn’t mean you walk in blind. Most of them leave a trail, and a buyer who knows where to look can read them by proxy.
Why Doesn't the Integration Plan Survive Close?
Because the data room captures outputs, and the risk lives in the system that produces them.
Culture is the way things get done around here, and like any system it has inputs (incentives, messages, expectations), energy (time, effort, friction), outputs (the results you want and the waste you don’t) and feedback loops. Diligence is very good at the outputs. Revenue, margin, churn and headcount all fit neatly in a spreadsheet. The machinery underneath doesn’t, and that machinery is what you’re actually buying. The moment two of those systems are bolted together, every hidden difference between them shows up at once.
Bring the plan into close, and bring the knowledge of where it will need to flex.
Five Things Diligence Can't Write Down, and the Proxy for Each
1. Who actually holds the knowledge. Diligence secures the leadership team, usually with earnouts, and assumes the knowledge comes along with them. It often doesn’t. The people who know how to run the business day to day are rarely on an earnout, and some of them walk in the first ninety days.
The proxy is always the people. Who do others go to when they have a question or a problem? Who, when things go sideways, knows where they need to go to get out of it? It isn’t necessarily the people who have been there the longest. In a perfect storm they aren’t at the helm. They’re on the quarterdeck, advising on what needs to be done and informing everyone of what’s actually happening. Find them early, then either keep them or get what they know written down and captured before they leave.
2. Risk tolerance between the two leadership teams. Nobody puts risk appetite in the data room, and it does not gel on its own. I worked an integration where one side had built its business on fixed-fee engagements: it carried the risk and automated hard to earn the bigger reward. The other side had been burned on fixed fee and retreated to time and materials. Getting those two postures to agree was much harder than anyone expected.
In our case the proxy was sitting in the contracts, and we could have seen it much earlier. Look at the deal types and engagement vehicles each leadership team signs off on, and at which ones they’re comfortable letting their direct reports approve without them. Put the two sides next to each other and you’ll see where they differ before it shows up in a pricing fight.
3. How long incentives lag the strategy. A new strategy can be announced on day one. The compensation plan that pays people to follow it can take up to a year to catch up. In that gap, the people most driven by incentives pull hardest in the old direction, and they’re doing exactly what they’re paid to do.
The proxy is the comp plan’s history. How often, and when, has the company changed its compensation plans? That tells you how fast it can move them. Then run the simple check: does the plan in place today actually pay for the direction the company says it’s going? Often the lag is apparent right there.
4. Change health. Think of it like physical fitness. A team that never changes gets out of shape. A team that changes too much is overtraining and starts hurting itself. Both show up after close.
At one company I was part of, we absorbed acquisition after acquisition with no time to digest any of them. What should have been a step function (change, then settle) became a never-ending hockey stick. It was chaotic, efficiency dropped, and it caused problems that took a long time to unwind.
The proxy has two lenses. The first is the count: reorganizations, system changes and leadership turnover over the last twelve to twenty-four months. The second is the quality of each one. Was it chosen, or was it shoved onto the organization? And was it absorbed? A change has landed when people can see the outcome, when they like it, and when it has become the norm. The last two are what make it stick.
5. Communication, or the silence that replaces it. Silence gets filled. When nobody tells people what the deal means for them, they write their own storylines, and every storyline points a slightly different way. That is where an integration starts to tip toward entropy, and alignment is not something you set once and walk away from.
A change has landed when people can see the outcome, when they like it, and when it has become the norm.
The proxy is to trace the last big change or announcement through people at several levels. How did they hear about it: from leadership first, or through the grapevine? Do they think it landed, and did they see it as a good thing? The same handful of conversations gives you hard evidence on change health too, so run them together.
The Bottom Line
None of these five will ever be in the data room. You can’t document them before close, and no amount of diligence will turn them into facts.
But you can investigate them. You can get a real feel for who holds the knowledge, how each side handles risk, how far the incentives lag, how much change the organization can absorb and how it talks to itself. And you can walk into Day 1 prepared for what you find.
Moltke’s point was never to stop planning. It was to plan knowing that execution changes the plan. So bring the plan into close, and bring the knowledge of where it will need to flex for the things that could never be in it.
A Pilot & Rutter principle.