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

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 wrong The one question — "Why are you actually doing this deal?" — that should govern every integration decision How American Airlines and US Airways turned a hostile takeover into a functioning merger Why decision velocity matters more than perfect information when two companies combine Where AI genuinely helps integration — and the one thing it will never do: read the room Episode timeline: 00:00 — Highlight from today's episode 01:20 — Introducing David Fubini and the topic 03:33 — "If you really know me…" 04:46 — David's definition of strategy 05:52 — What makes post-merger integration uniquely hard 06:47 — The Integration Management Office: engine, not afterthought 10:33 — Merger or takeover? Inside American Airlines–US Airways 14:05 — Why there's no playbook, only an integration mindset 17:30 — The first thing that can undo a deal: losing the base business 21:28 — 70% confidence and trading time for data 22:59 — Sequential, interdependent decisions under pressure 25:04 — Designing the governance structure 27:06 — Assimilating culture, and the leader's role in modelling it 32:31 — Integration as a design effort 36:59 — Synergies, baselines and where cost capture goes wrong 39:52 — Will AI make integration easier — or just fail faster? 41:52 — Why modern strategy demands deals, not just organic growth 44:50 — Closing thoughts Additional resources: Post-Merger Integration: hhttps://www.hbs.edu/faculty/Pages/ite... David Fubini on LinkedIn:   / david-fubini-b0009bb   David Fubini, HBS faculty: https://www.hbs.edu/faculty/Pages/pro... Thank you to our guest, David Fubini. Thank you to our executive producer, Zach Ness, our producer, Nazanin Homayoun Jam, our editor, James Pearce, and the rest of the team. If you like what you heard, please follow, download, and subscribe. I'm your host, Kaihan Krippendorff. Thank you for listening.