Why most M&A deals fail to deliver their synergy targets

By Patrick Heinemann, Gerd Christian Finck and Jörg Delhaes

Every merger, acquisition, or joint venture rests on a synergy rationale – the commercial logic that makes the transaction worth doing. Yet for most companies, the gap between what is promised at signing and what is ultimately delivered is wide, persistent, and costly. A new Roland Berger report, based on a survey of senior M&A experts across major industries, examines why synergy delivery so consistently falls short – and what it takes to build a system that reliably closes that gap.

The execution gap that starts before signing

The data is unambiguous: Repeatable synergy delivery remains the exception, not the norm. Across the M&A landscape, only a small minority of acquirers consistently achieve their full synergy targets. The reasons are structural, not incidental – and they are almost always visible before the deal is signed.

The critical inflection point is not Day 1, nor the post-merger integration kick-off. It is the moment when the synergy case stops being a hypothesis and becomes a commitment. Once targets enter the board pack, the question shifts from "is this number right?" to "how do we defend it?" From that moment forward, challenging the case becomes organizationally difficult – and the foundations of underperformance are quietly laid.

Our research points to two compounding failures at this stage. First, independent challenge mechanisms are far less common than they should be: Fewer than half of respondents have a formal process to stress test synergy assumptions before signing. Second, clear ownership of individual value levers is rarely assigned before integration begins. Together, these gaps reveal a structural issue: Many deals enter execution before the organization has genuinely tested whether the synergy targets are realistic, owned, and deliverable.

Why commercial synergies demand cultural readiness

Cost synergies tend to be modeled, benchmarked, and assigned with relative ease. Revenue synergies are a different matter. They depend on cross-selling, joint account coverage, aligned pricing decisions, and the willingness of recently merged teams to share customers and relationships. These are behaviors that cannot be assumed – they must be built.

Yet our survey shows that a significant share of companies begin revenue synergy planning only after signing. For a value lever that depends on trust and behavioral change between previously separate organizations, that timing represents a material risk. The opportunity to lay the cultural groundwork – aligning incentives, retaining key commercial talent, defining how sales teams will work together – is lost before Day 1 even arrives.

The implication is clear: Culture is not a soft topic to be addressed during integration. It is a core commercial input that must be treated with the same rigor as the financial model. The behaviors required for revenue synergies to work need to be in place from the deal announcement, not after closing.

Governing value beyond Day 1

Many organizations treat the synergy register as a fixed document once the deal closes. Workstreams are mobilized, reporting begins, and the signed targets become the ceiling. But the best acquirers take a fundamentally different approach: They treat post-close data access as the starting point for a second, more informed round of value discovery.

The rationale is straightforward. Before closing, every synergy case is built on partial information. After closing, the full picture emerges – actual cost structures, margin profiles, customer relationships, system interdependencies, and talent realities. Leading acquirers build governance models that capture this new information systematically, distinguishing between committed value, realized value, value at risk, newly discovered upside, blocked decisions, and required management interventions.

Critically, our research shows that post-signing upside rarely rescues underperforming targets. Most respondents say newly identified levers only partially – or not at all – offset shortfalls against signed targets. Leading acquirers therefore separate two things: protecting the committed number and adding validated new value. They use real-time tracking to reduce decision latency and intervene before value is lost.

A framework that turns targets into results

Our report introduces a structured value operating system – designed to close the gap between synergy ambition and delivered value. Built around five sequential disciplines, the framework links deal thesis, synergy modeling, cultural readiness, integration governance, and post-close discovery into a single, implementable logic.

The framework is grounded in a clear principle: Synergy delivery does not fail at execution. It fails at the earlier stages where assumptions go unchallenged, ownership is left undefined, and cultural prerequisites are treated as secondary concerns. Addressing these failure modes systematically – before the deal is signed, before Day 1, and beyond – is what separates consistently high-performing acquirers from the rest.

The full report sets out the evidence behind each dimension of the framework, along with specific recommendations for M&A leaders looking to build a more disciplined approach to value capture.

We would like to thank Adrian von Lewinski, Project Manager, for his valuable contribution to this article.

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