The deal closes, the announcement is made, leadership teams are photographed shaking hands, and then the real work begins. For most organisations, that is where it goes wrong. Fortune’s analysis of more than 40,000 acquisitions worldwide over four decades shows that 70-75% of acquisitions fail to deliver the value their original rationale promised. The reason is almost never the strategy. The strategic logic of most deals is sound: market share, capability acquisition, cost consolidation, technology access. McKinsey’s research shows that M&A transactions underperform due to integration execution issues rather than flawed strategic rationale, with organisational friction, operating model disruption, and cultural misalignment as the primary drivers of value leakage post-close.

The Target Operating Model is where that value is either realised or lost. Understanding what it is, how to design it well, and why most organisations get it wrong is the difference between a deal that justifies its premium and one that becomes a write-down.

What The TOM Actually Is

A Target Operating Model is not an organisational chart. It is not a project plan or a list of integration workstreams. It is the answer to a single, deceptively complex question: how will this combined organisation actually work?

That answer spans the full breadth of the business: who is accountable for what decisions, which processes run the combined entity, what technology and data infrastructure supports them, how risk and compliance functions are structured, and what culture and behaviours hold the whole thing together. In regulated financial services, the TOM carries an additional obligation. It is not only the blueprint for operational design, it is the document against which regulators, auditors, and boards will assess whether the combined institution is under control.

Post-merger integration presents a rare opportunity for financial services institutions to reshape their technology landscape, strengthen operational resilience, and accelerate strategic priorities. The real challenge, however, is often organisational, and this includes the challenge of making decisions fast enough, with the right accountability and governance, while maintaining regulatory control. Many programmes drift here, not due to a lack of effort, but due to a lack of integration architecture across people, processes, and technology. Integration architecture, not integration activity. The volume of activity in post-M&A environments is never the problem. What fails is the architecture that connects it.

Start With The Deal Rationale

Before any design work begins, the leadership team must achieve clarity on why the deal happened. Was this a cost play? A capability acquisition? A market expansion? A technology bet? The TOM design follows directly from that answer, and misalignment between the deal rationale and the operating model design is one of the most reliable predictors of integration failure.

A deal built on cost synergy requires an operating model that enables rationalisation: shared services, consolidated platforms, eliminated duplication. A deal built on capability acquisition may require the opposite: protecting the target organisation’s ways of working from being absorbed and standardised out of existence. The right integration model is not always full absorption. Sometimes value is maximised by integrating only what is necessary and preserving what makes the target valuable.

Acquiring organisations often apply a uniform integration logic regardless of deal type, restructuring the acquired business using their own operating templates and calling it integration. In many deals, integration design is nobody’s explicit responsibility. Corporate development teams close the deal, programme teams inherit constraints, functional leaders default to standardisation, and nobody truly designs the future operating model. That is an ownership problem, not a tooling problem. The TOM process must begin by naming that ownership explicitly, before the design itself starts.

Four Dimensions That Must Be Resolved

Effective TOM design requires clear decisions across four interconnected dimensions. Each has its own logic, its own timeline, and its own failure modes. Treating them as a single problem is one of the more common sources of integration confusion.

• Structure and Decision Rights: The question here is not where the boxes sit on the chart, but who is accountable for which decisions, at what level, and with what authority. In regulated environments, this extends beyond the business to encompass the first and second lines of defence. End-to-end accountability must be clear across ICT risk management, control design, evidence production, and risk-informed approvals. What typically goes wrong when integration programmes stall is that decisions are not made with sufficient control, resulting in late-stage rework, delayed sign-offs, and increased supervisory exposure. Decision rights that are ambiguous at the start of integration become contested under pressure. They need to be documented, agreed, and accessible to the people who will rely on them.

• Processes: Not all processes from both organisations can or should survive. The TOM design must make decisions about what is kept, what is harmonised across both entities, and what is retired. These are not purely efficiency decisions. In financial services, process decisions carry compliance and audit implications. A successful merger requires integration of systems encompassing risk management, information technology, and compliance with regulatory requirements. Compliance problems arise when management is unfamiliar with the regulatory requirements associated with activities inherited through merger, or when the combined institution crosses reporting thresholds as a result of the deal.

• People and Culture: This is the dimension most consistently underestimated, and the most consistently cited as the reason deals fail. Organisations looking to expand through acquisition continue to prioritise financial modelling and legal diligence at the expense of cultural integration, with research identifying this as a critical blind spot in modern M&A transactions, with businesses consistently underinvesting in the human systems that most determine deal success. Culture is not a soft consideration to be addressed after the structural and technical work is complete. It is an operating condition. Two organisations bring with them distinct assumptions about how decisions get made, how disagreement is expressed, how accountability is held, and what good performance looks like. When those assumptions collide without deliberate management, the result could be paralysis. 30% of transactions fail to meet financial targets due to cultural issues, leading to low productivity, loss of key talent, customer disruption, and value destruction.

• Technology, Data, and Controls: In financial services, this is where regulatory exposure concentrates most acutely during integration. Legacy platforms running in parallel, temporary technology arrangements that extend indefinitely, and data environments that do not reconcile across the combined entity are not just operational problems. They are governance failures with direct supervisory implications. Parallel operation of legacy platforms, duplicate control environments, and temporary outsourcing setups must be justified not only economically but also through demonstrable governance, control effectiveness, and evidence production. Extended parallel runs become increasingly difficult to sustain, especially for platforms supporting critical functions. The TOM must treat platforms as assets with defined lifecycles, not as inherited infrastructure to be addressed when capacity allows.

Sequencing is a Governance Decision

One of the most consequential design choices in post-M&A TOM work is sequencing. That is, what gets integrated first, what follows, and what can wait. Organisations that try to run all workstreams simultaneously rarely succeed. Those that sequence without sufficient thought about regulatory and control implications create exposure that is difficult to unwind. In regulated financial services, there is a logic to sequencing that must be respected. Day one is not a full integration. It is operational stability, ensuring that the combined entity can serve its customers, meet its regulatory obligations, and demonstrate that controls have not deteriorated as a result of the transaction. Everything else follows from that foundation.

The practical sequence is this: stabilise customer-facing operations and regulatory reporting first; establish clear accountability and decision rights across the first and second lines; align risk and control frameworks before consolidating platforms; rationalise processes and technology incrementally, with evidence of control maintained at each stage.

Integration OKRs should be a direct reflection of the deal’s strategic intent, ensuring that execution priorities remain anchored in value creation rather than activity completion. High-performing integration programmes reinforce this with a shared definition of ‘done,’ ensuring outcomes are only considered complete once architectural, security, data, and compliance criteria have been met. A workstream is not complete because it has been executed. It is complete because the outcome it was designed to achieve, including the regulatory and control dimensions of that outcome, has been validated and evidenced.

Governance Architecture That Serves the Integration

In regulated financial services environments, governance structures often expand rapidly during post-merger integration. While appropriate control is essential, governance that focuses primarily on activities, approvals, and status reporting can dilute ownership and slow decision-making. Effective integration governance shifts the focus from monitoring tasks to steering towards outcomes. This is one of the most practically important observations about post-M&A governance, and one of the most frequently ignored. Integration programmes accumulate governance quickly: steering committees, programme boards, workstream leads, risk forums, regulatory working groups. Each layer is added for a legitimate reason. Collectively, they often create an environment where accountability is diffuse, decisions require multiple forums to ratify, and the programme manages its governance rather than its outcomes.

The design principle for integration governance is clarity of ownership at each level, with decision rights that are proportionate to the risk of the decision. Strategic decisions belong at the most senior level and should be made there, not deferred into sub-committees. Operational decisions should be made by the people closest to the work, with the authority to make them. Escalation pathways must be defined and used deliberately, not as a default when accountability is uncertain. Decisions must be posted with their rationale and evidence source within a defined window, and compliance alignment must be verified with relevant regulatory frameworks. The governance design is only complete when decision clarity, speed, and confidence can be evidenced.

Measures of Success

The most reliable indicator that TOM design has succeeded is not the completion of integration workstreams. It is whether the combined organisation is delivering the value that justified the deal in the first place. Those metrics must be defined before the integration begins, not after. They should map directly to the deal rationale: cost synergy realisation, customer retention across the combined entity, time to market for combined capabilities, control effectiveness ratings, regulatory confidence in the combined institution’s governance. Without that linkage, integration activity becomes an end in itself, and the deal’s original promise becomes a memory rather than a target.

Once there is clarity about the interim and end-state operating model, the distinction between what must change on day one versus what can follow later becomes essential. That distinction, made deliberately and early, is what prevents value destruction before the deal closes. The TOM is not finished when the design is complete. It is finished when the value the deal promised is visible in the performance of the combined organisation. Until then, it is a work in progress, and it requires the same leadership attention and governance discipline after close as it did in the design phase.

Aiversight works with risk and compliance leaders in regulated financial services on operating model design, accountability architecture, and the governance conditions that determine whether strategic intent survives contact with integration reality. If your organisation is navigating a post-deal operating model challenge, we are available to discuss it.