Buy-and-build is the defining PE software M&A playbook in Europe, but one integration mistake quietly destroys more value in bolt-on acquisitions than any other: customer confusion in the three to twelve months after completion, when nobody owns the customer experience across both product lines. This post explains why post-merger integration in SaaS is a customer retention problem as much as a technology one, using research from Bain, McKinsey, Benchmarkit, Software Equity Group and Willis Towers Watson on buy-and-build outcomes, merger customer losses, gross revenue retention benchmarks and talent flight. It sets out a sequenced integration model (single customer owner, communication plan, thirty-day health assessment, unified onboarding and support, cross-sell) and shows how retention across the combined entity shapes the exit multiple. Written for PE operating partners, portfolio CEOs and software investors.

This 100-day post-acquisition SaaS playbook is built for PE operating partners, portfolio operators, and management teams navigating the critical first months after a SaaS acquisition, drawing on direct experience across 62 portfolio companies to show why the strongest post-acquisition outcomes come from diagnosing before prescribing rather than rushing to install a pre-built growth plan. Covering the real drivers behind early NRR decline, sales rep attrition, ICP drift, and inflated pipeline conversion problems, the piece breaks down the sequencing that separates portfolio companies creating measurable value fast from those still firefighting at month eighteen, and explains why SaaS businesses are uniquely vulnerable to hidden operational fragility that ARR alone won't reveal for six to twelve months. Written for PE firms, operating partners, and SaaS leadership teams managing post-acquisition integration, customer success scaling, and commercial due diligence, this is a practical framework for the first hundred days rather than generic M&A advice, grounded in what actually happens inside SaaS businesses once the deal closes.