#170 – Why Most Mergers Fail After the Deal Closes: David Fubini

David Fubini spent 34 years at McKinsey & Company, where he was a Senior Partner, Managing Director of the Boston office, and co-founder of the firm's Worldwide Merger Integration Practice — leading dozens of the world's largest M&A transactions. He's now a Senior Lecturer at Harvard Business School, where he co-leads the Mergers & Acquisitions and Leading Professional Services Firm programmes. He's the author of Post-Merger Integration: Building the Mindset, Skills, and Discipline Needed for Deal Success (Wiley, 2026), co-written with Patrick Sanguineti, and the earlier Hidden Truths: What Leaders Need to Hear but Are Rarely Told.Most leaders obsess over closing the deal — the strategy, the financing, the negotiation. But according to David, that's not where deals break down. They fail in the messy weeks and months after the ink is dry, when two organisations, two cultures and two workforces actually have to become one. Hundreds of billions in promised synergies are lost every year to integration that was treated as an afterthought rather than the engine of the whole transaction.In this episode, we dig into why so many companies under-resource the integration effort, why your most capable people — not your spare capacity — should be running it, and why David deliberately refuses to hand leaders a step-by-step playbook.In this episode we cover:Why the Integration Management Office is the real engine of a deal — and why companies staff it wrongThe one question — "Why are you actually doing this deal?" — that should govern every integration decisionHow American Airlines and US Airways turned a hostile takeover into a functioning mergerWhy decision velocity matters more than perfect information when two companies combineWhere AI genuinely helps integration — and the one thing it will never do: read the roomAdditional resources:Post-Merger Integration: hhttps://www.hbs.edu/faculty/Pages/item.aspx?num=69100David Fubini on LinkedIn: https://www.linkedin.com/in/david-fubini-b0009bb/David Fubini, HBS faculty: https://www.hbs.edu/faculty/Pages/profile.aspx?facId=102821Thank you to our guest, David Fubini. Thank you to our executive producer Zach Ness, our producer Nazanin Homayoun Jam and our editor James Pearce. If you enjoyed this episode, please follow, download, and subscribe. I’m your host, Kaihan Krippendorff—thank you for listening.Follow us at outthinker.com/podcast