[Hassaan Khan]

Mergers and acquisitions go far beyond numbers. Understanding deal types, strategizing for success, managing the buy side, and conducting effective due diligence each step can make or break a deal. Yet some areas are consistently underestimated, even though they end up having the biggest impact on long-term success. In your experience, which of these areas tends to be most underestimated but ends up having the biggest impact on deal success? I’d love to hear your insights!

[Miguel Cortijo Antona]

Hi Hassaan, thank your for your insight and questions. From my perspective the most underestimated factor is cultural integration, often dismissed as “soft,” yet it determines whether people collaborate, stay, and deliver post‑deal value. Effective deals succeed not just on financial logic but on aligning behaviors, decision‑making norms, and leadership styles. A real‑world example: Disney’s acquisition of Pixar: Leadership from both sides intentionally aligned cultures, preserving Pixar’s creative identity while integrating Disney’s scale. It can be argued that this cultural stewardship directly contributed to sustained innovation and successful post‑merger output.

[Aneta Podsiadla]

In my experience, one of the most underestimated areas that can make or break a deal is data protection. Often, teams focus on financials, market fit, and operational synergies, while privacy and cybersecurity risks are treated as a compliance checklist.

In reality, inadequate attention to data protection can have major consequences:
Regulatory risk: Violations of GDPR, CCPA, or other privacy laws can lead to fines, deal delays, or even blocked transactions.
Hidden liabilities: Legacy contracts, third-party data processors, or unclear consent frameworks can surface post-closing, affecting valuation.
Operational disruption: Integrating IT systems and data governance post-merger without a clear plan can slow down the integration and erode expected synergies.
Reputational impact: Customer and partner trust can be quickly damaged if data breaches or mismanagement occur.

Proactively assessing data protection during due diligence and planning for robust governance post-closing can turn this risk into a competitive advantage, rather than a liability.

[Fahmid Ibne Siraz Taseen]

Hi Hassaan, Miguel, and Aneta,

This is an excellent discussion that highlights the true complexities of modern dealmaking.

Miguel, your assessment of cultural integration is spot on. The contrast between Disney’s intentional preservation of Pixar’s creative autonomy and its aggressive, centralized consolidation of 21st Century Fox perfectly illustrates how cultural stewardship directly dictates value creation or destruction.

Aneta, your warning regarding data protection is equally critical. Relegating cybersecurity to a basic compliance checklist often leads to catastrophic financial and regulatory consequences. The Marriott-Starwood acquisition is the prime example of this, where a failure to conduct proper cybersecurity due diligence on legacy systems resulted in the inheritance of a massive, multi-year data breach and a proposed £99 million GDPR fine from the UK Information Commissioner’s Office.

However, if we are looking for the absolute most underestimated area that acts as the hidden anchor for M&A failure, it is the integration of technical debt.

When acquiring a company, you aren’t just buying its market share or talent; you are inheriting the historical compromises of its IT and engineering departments. Technical debt is estimated to amount to 20 to 40 percent of an entire technology estate’s value. This debt acts as the underlying infrastructure that actually causes the cultural and data protection failures mentioned above:

Impact on Culture: Forcing acquired talent to abandon innovation in order to perform triage on incompatible, undocumented legacy systems is a primary driver of developer frustration and post-merger talent flight.

Impact on Data Protection: Outdated data security protocols embedded deep within legacy systems and unsupported software libraries are the exact vulnerabilities that lead to the catastrophic breaches and regulatory penalties you mentioned.

Ultimately, financial logic, cultural alignment, and data protection cannot survive the friction of a “big bang” IT integration if the underlying technical debt isn’t audited, quantified, and actively remediated from day one.

Thank you for starting such a crucial conversation!

[Saeedeh Sadjadi]

Thank you all for the insightful perspectives – what really stands out to me is how each of these “underestimated factors” connects to the same underlying theme: the hidden complexity beneath the surface of a deal. Cultural integration, data protection, and technical debt may seem like separate issues, but in reality they intersect and compound one another during post‑merger execution. In many FMCG deals, the focus leans heavily toward commercial synergies and portfolio logic, yet the long‑term value is often won or lost in these less visible layers. I find it especially compelling that cultural friction, legacy IT systems, and data‑governance risks can quietly erode even the strongest strategic rationale. This reinforces the idea that successful acquirers don’t just evaluate the business they’re buying — they evaluate the operating reality they’ll have to integrate, and plan for it early.

[Nicolas Clement]

Dear Hassaan,
Beyond data protection, I would quote 3 main ares which are underestimated or overlooked.
1. Failure to align internal interests (one’s own board of Directors) to have a clear mission & purpose, the “why” for the deal. Imagine you have a mission from your Board of Directors to buy at 150 a company valued at 100. There is a high risk that the seller will refuse to sell. What do you do? Offer 150? But what will your share price do when you pay 150 for a firm valued at 100? Offer 50 ? But what happens to you immediately after you tell your Board they refuse to speak with you because you offered 50 (and you had a mandate at 150)?

2. Failure to have a full map of decision makers, not only in the acquirer’s and the target’s organizations, but also in the whole industry ecosystem and beyond. In 2008-2009, Coca Cola failed its acquisition of a Chinese leader by announcing their great victory, the agreement reached for a few billion dollars (I don’t remember the exact figure) showing their superiority on the FMCG market. This was not at all to the taste of the Chinese government, who ruled the acquisition illegal. If Coca Cola had taken national pride into account and announced that even though they succeeded in their acquisition, their counterpart had driven the hardest bargain ever and that in a sense the acquisition was a victory of the target (cf. the Cadbury defense…), the outcome might have been totally different.
Fast forward to today, the premature announcement by Netflix of Warner’s acquisition for $83b failed to recognize a hidden decision maker based in Washington DC, who may have been instrumental in Paramount’s counter offer at $110b all cash.

3. A misguided belief in rational negotiation. The higher the stakes, the higher the emotions, the higher the irrationality. Hubris sets in, mistakes are made, the need for the deal leads to bad deals. In 2001, a famous perfume distribution network was interested in another one. The target’s owner said: it’s $120m, all cash, no due diligence, vail 2 weeks (aythentic). The acquirer said yes, convince they could bundle their combined distribution networks and sell them to al eading luxury brand owner of a global leader in perfume stores. But they were not interested, the acquirer went bankrupt and was “purchased” by Chinese investors.

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