Post-Acquisitions Gone Wrong: Lessons from the First 90 Days

I’ve been through a few acquisitions where the ink dried on the deal, champagne bottles popped, and everyone felt like they’d just won the lottery. But I’ve also been there 90 days later when reality set in when “synergies” turned into silos, margins eroded, and leadership teams felt more like firefighters than operators. In manufacturing M&A, the post-acquisition phase makes or breaks the deal. A Harvard study found that 70–90% of acquisitions fail to deliver expected value, and in my experience, most of that failure happens in the trenches of operations, not the boardroom. Here are 3 lessons that have stuck with me: Speed without structure collapses. I once joined a company where leadership pushed to double production capacity immediately post-close. Six months later, OEE dropped 22%, scrap tripled, and customers were threatening to leave. Why? No one had stabilized processes before scaling. Culture eats integration for breakfast. In another case, we tried to overlay corporate systems on a plant that had been family-run for 30+ years. We lost half of middle management in 60 days because no one took the time to explain why the change mattered. The EBITDA miss that year was 18%. The first 90 days set the tone. In one turnaround, we prioritized stabilizing supply chain and shop floor processes before chasing growth. That decision alone flipped EBITDA from negative to positive within the first year and gave the acquirer confidence to invest more aggressively. I often get asked, “What should I be looking for after the deal closes?” My answer: don’t just look for problems, look for leverage points. Diagnose fast, act decisively, and set a rhythm of communication that aligns teams from day one. Next week, I’ll be sharing more about this in a webinar (event can be found here on Searchfunder, link below) called “Welcome to the First 90 Days: Turning Operational Chaos into Profit.” It’s focused on giving searchers, operating partners, and investors a playbook for capturing value quickly without burning out teams. I’d love to hear from others who have been in the trenches: What’s the biggest post-acquisition mistake you’ve seen, or the smartest move that created outsized value?