Every acquisition has a synergy case. It sits in the deal model, underpins the valuation, and gets presented to the investment committee with enough conviction to justify the premium. In most cases, it does its job — the deal gets approved.
The problem starts on Day 1, when the synergy case in the spreadsheet needs to become a synergy capture programme in the real world. This is where the gap opens. The number in the model is precise. The programme required to deliver it is complex, politically charged, and dependent on execution by people who weren’t in the room when the number was agreed.
The firms that consistently capture synergies are not the ones with the most aggressive synergy cases. They are the ones with the most rigorous capture programmes. This article outlines what separates the two.
Why Synergy Cases Consistently Overstate
Synergy cases overstate for structural reasons, not because people are dishonest.
Cost synergies are estimated top-down. A common approach is to identify overlapping cost categories — property, IT, procurement, corporate functions — and apply a percentage reduction. This produces a number that is directionally correct but operationally vague. It doesn’t account for the sequencing of actions required to capture each saving, the transition costs, the contractual constraints, or the organisational resistance. A top-down estimate of £5 million in procurement savings becomes, on closer examination, a programme of 40 individual renegotiations with different timelines, different contractual terms, and different levels of supplier dependency.
Revenue synergies are aspirational by nature. Cross-selling is the most commonly cited revenue synergy, and the most consistently overestimated. The assumption that the combined entity’s sales force will immediately begin selling both product sets to both customer bases ignores the practical barriers: sales teams need training, incentive structures need alignment, customers need to be receptive, and the combined offering needs to be genuinely compelling — not just bundled. Revenue synergies that assume “we can sell their product to our customers” without a detailed go-to-market plan are wishes, not synergies.
Timing is almost always too aggressive. Synergy models frequently show full run-rate savings in Year 1 or Year 2. In practice, most cost synergies take 12–24 months to reach full run-rate once you account for notice periods, contract terms, transition timelines and the time required to redesign processes. Revenue synergies typically take 18–36 months to materialise. A model that shows 80% of synergies captured in Year 1 is, in most cases, unrealistic.
What a Real Capture Programme Looks Like
A synergy capture programme that actually delivers has five characteristics.
Bottom-up initiative tracking. Every synergy should be decomposed into specific, named initiatives with defined scope, a financial estimate, a named owner, a timeline, and dependencies. The procurement synergy isn’t £5 million — it’s 40 separate workstreams, each with its own trajectory. This granularity is what enables tracking, accountability and early intervention when initiatives stall.
A dedicated programme management office. Synergy capture does not happen by itself. It requires a persistent, empowered team that tracks progress weekly, escalates blockers, maintains the financial bridge between planned and actual savings, and holds initiative owners accountable. This PMO should report directly to the integration steering committee and have the authority to escalate issues to senior leadership.
Separation of ‘identified’ from ‘captured.’ A synergy is not captured when it’s identified. It’s not captured when a plan is agreed. It’s captured when the saving or revenue appears in the P&L. The distinction matters enormously, because the gap between identification and P&L impact is where most value leakage occurs. Rigorous programmes track synergies through a pipeline: identified, validated, actioned, realised. Movement between stages requires evidence, not assertion.
Honest treatment of dis-synergies and transition costs. Every integration creates costs as well as savings. Redundancy payments, system migration costs, dual-running periods, re-branding, and customer migration all consume cash that should be netted against the gross synergy figure. The firms that report net synergies — after transition costs — have a much more accurate picture of whether the deal is creating the value it promised.
Regular recalibration. The synergy case was built before the deal closed, with imperfect information. Post-close, the acquirer learns things that change the picture — some initiatives are harder than expected, others are easier, new opportunities emerge that weren’t in the original case. A good capture programme recalibrates quarterly, updating estimates based on actual progress rather than defending the original model indefinitely.
The Practitioner’s View
The synergy case is a hypothesis. The capture programme is the experiment that tests it. The firms that treat synergy realisation as a rigorous operational discipline — with bottom-up tracking, dedicated programme management, and honest reporting — consistently outperform those that treat it as a finance exercise that resolves itself.
If your synergy tracking consists of a quarterly report from the CFO’s team comparing actuals to the deal model, you’re not tracking synergies. You’re watching them — and there’s a meaningful difference.
Aethon Ventures provides management consulting to PE/VC funds, mid-market businesses and corporate development teams across Growth, Profitability, M&A and Transformation. London-based with consulting partnerships in India and Malaysia.
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