The deal thesis isn’t enough!

How many of us have sat in the room where the decision to buy was made somewhere else and now it’s our job to integrate the business and deliver on a deal thesis that may not be entirely realistic?

I’ve been involved in multiple M&A transactions over the years, from both the buy and sell sides, in Ireland and across multiple geographical jurisdictions as a senior HR leader.

And one lesson comes up repeatedly: the deal thesis is only the beginning.

PwC’s new 2026 M&A Integration Survey puts some useful evidence behind that. Only around one-third of acquirers fully achieved all of their priority deal objectives, with PwC pointing to the gap between the investment thesis and the practical decisions needed to make it real.

One statistic particularly stood out to me: only 16% conducted pre-signing leadership, talent or organisational diligence.

Wow. 16%.

Because we all know what can happen in the absence of that diligence. Assumptions are made about structures and capability. Decisions can be influenced by personalities, existing relationships or a reluctance to unsettle those already occupying comfortable seats. Sometimes the organisation design is effectively inherited rather than consciously designed around what the deal actually needs to deliver.

Then the deal closes and the integration team inherits those assumptions along with the financial targets.

That’s when the difficult questions really begin:

• Who should lead what, rather than who currently does?

• Where should decision rights sit?

• What operating model will actually deliver the deal thesis?

• What capability is critical to retain?

• Where are the leadership and cultural risks?

• And is the original thesis still achievable once it meets operational reality?

Having worked through acquisitions and integrations across different businesses and jurisdictions, I’ve seen how important it is to surface these questions early.

People decisions aren’t something to bolt onto an integration plan after the transaction. They are deal decisions.

And sometimes the most valuable contribution HR makes is being prepared to challenge the assumptions the deal arrived with. These questions become even more important when integration crosses businesses, cultures and geographical boundaries.

For me, the message is simple: people decisions are not something to bolt onto an integration plan after the transaction. They are deal decisions

For full access to the survey click here.