The 5 Biggest M&A Mistakes That Can Derail a Deal 🚨
- Manyi Kiss
- Mar 17
- 1 min read

Hi, I’m Manyi Kiss, Customer Success Manager at CGPH Group, specializing in Mergers & Acquisitions.
Throughout my career, I’ve seen ambitious M&A deals fail—not because of bad intentions, but due to avoidable mistakes that undermine long-term value.
Here are five critical errors that can turn a promising transaction into a costly setback:
✅ 1. Overestimating synergies Too often, companies enter deals expecting seamless cost reductions, operational efficiencies, and revenue growth. The reality? Synergies take time and can be far more complex—and expensive—than anticipated.
✅ 2. Inadequate due diligence Buying a company without thorough due diligence is like purchasing real estate without an inspection. Undisclosed liabilities, financial risks, and cultural misalignment can erode deal value after closing.
✅ 3. Poor post-merger integration planning Signing the deal is just the beginning. Without a structured integration strategy—covering operations, talent retention, and corporate culture—even the best acquisition can struggle to deliver expected results.
✅ 4. Ignoring cultural alignment An acquisition is more than just financials and market share. If leadership styles, organizational values, or internal cultures clash, employee engagement and productivity can plummet—putting the entire investment at risk.
✅ 5. Lack of a clear strategic rationale M&A should be driven by long-term strategic fit, not just growth for growth’s sake. Without a defined value creation plan, businesses risk spending significant capital without achieving sustainable competitive advantage.
📢 M&A can be a powerful tool for growth—but only if executed with precision. If you’re navigating a deal and want to ensure long-term success, let’s connect. 📩