Acquisition Integration Firms
Most deals are won at the LOI and lost in the first 100 days. The diligence was clean, the model was sound, and then the two companies tried to actually become one — and the synergies stalled, the good people left, and the integration plan turned out to be a spreadsheet nobody owned. Stonehill is the acquisition integration firm that gets hired to keep that from happening. We work shoulder-to-shoulder with PE-backed and founder-led companies to turn a signed deal into a single, functioning business — on schedule, with the value thesis intact.
The integration gap is where value disappears
Plenty of firms can help you buy a company. Far fewer can help you absorb one. That gap — between close and a fully integrated operation — is where most of the deal's promised value is created or quietly forfeited.
The middle market feels this acutely. A $50M–$1B business rarely has a standing integration office, a bench of program managers, or a playbook from the last ten acquisitions. The operating team is already running the company. Asking them to also run the integration, in their spare time, is how Day One targets slip and synergy cases go unrealized.
That's the work we do. Not advice from the sidelines — integration that actually gets executed.
What an acquisition integration firm should actually deliver
Acquisition integration (post-merger integration, or PMI) is the disciplined process of combining two organizations — their people, operations, systems, customers, and finances — into one company that performs better than the parts did separately.
Done right, it covers the full arc:
Pre-close planning — integration strategy, Day One readiness, and a 100-day plan tied directly to the value thesis
Day One execution — the operational, financial, and communications steps that have to land on the first day of combined ownership
The first 100 days — standing up the integration office, sequencing the workstreams, and capturing the early synergies that fund the rest
Steady-state operations — driving the deal model home and handing a stable, integrated business back to the operator
Stonehill is built to run that entire arc, or to plug into the stage where you need the most help.
A boutique built on senior operators, not a staffing pyramid
When mid-market sponsors compare acquisition integration firms, the real choice is between two models.
The global advisory shops bring scale and a recognizable name — and a leverage model where the senior partner who sold the work hands the room to a rotating bench of analysts. You pay enterprise rates for a learning curve.
Stonehill runs the other way. The people in your integration room are the people doing the work. We staff lean, senior, and accountable, with a methodology disciplined enough to keep seven workstreams moving and human enough to keep your best people from walking out the door. Substance over slide count.
For a founder-led business or a PE platform doing its first bolt-on, that difference is the difference between an integration that drags and one that closes on time.
Our integration methodology
Stonehill pairs a structured, process-driven framework with Design Thinking — because integration is an operational problem and a human one. Tools alone don't carry a deal; people do. We organize the work into a clear set of workstreams, coordinated by a single Integration Management Office (IMO) so nothing falls between the seams:
Integration Management Office — governance, cadence, decision rights, and a single source of truth
Finance & Accounting — close-the-books readiness, reporting, controls, and synergy tracking
Operations & Supply Chain — the production and service backbone that has to keep running through the transition
Commercial & Go-to-Market — protecting revenue, retaining customers, and capturing cross-sell
People & Organization — org design, retention of key talent, and the cultural work that makes or breaks a merger
Technology & Systems — pragmatic systems integration sequenced to the business, not the IT roadmap
Synergy Capture — turning the value thesis into tracked, owned, dollar-denominated initiative
Every workstream rolls up to a live plan with named owners and dates — the opposite of a binder that gets admired once and shelved.
Who we serve
Stonehill works with:
Private equity sponsors and operating partners integrating platforms and bolt-ons across a portfolio
PE-backed portfolio companies absorbing an acquisition without a standing integration team
Founder-led and family businesses going through their first major merger or sale-driven transitio
We focus on the middle market — companies roughly $50M to $1B in revenue — where a boutique with senior bench depth makes the most difference and a global firm's overhead makes the least sense.
Track record
Stonehill grew into a post-merger integration boutique because clients kept asking us to stay past the strategy and help them actually execute the close. Over the years our teams have supported strategy and integration work for organizations spanning financial services, consumer, logistics, and multi-site operations. We bring that operating experience into every deal room
Don't let the value walk out the door
The deal model assumes the integration works. Make sure it does. Stonehill brings senior operators, a disciplined integration framework, and a Design Thinking approach that keeps your people and your synergies intact from signing through steady state.
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