External growth, an accelerator of development

01. Why external growth?

There are two ways to grow a company. Organic growth — winning clients, opening branches, launching new offerings — builds over the long term but moves at the pace of the market. External growth — acquiring existing companies — makes it possible to move up a level in a matter of months rather than several years. The two are not mutually exclusive: the strongest trajectories combine them.

What an acquisition delivers immediately

• A stronger territorial network: each target comes with its locations, its local teams and its knowledge of the field.
• Complementary client portfolios: recurring revenue acquired from day one, with no commercial acquisition cost.
• New areas of expertise and new business lines: know-how that would take years to develop in-house.
• A mechanical acceleration of revenue: the scale acquired improves negotiating power, commercial credibility and access to major accounts.
• Entry into new regions: establishing a presence by acquiring an established local player is faster and less risky than starting from scratch.

But you still need to know how to execute. Buying a company is simple on paper; creating value with your acquisitions is a profession in itself. To understand what separates a successful build-up from a collection of poorly integrated companies, this guide analyses a real and recent case: NSI Groupe, a mid-sized company from northern France that has become, in just a few years, one of the most active consolidators in its sector.

02. NSI Groupe: the trajectory

Founded in 2012 in Marly, near Valenciennes, by Romain Tellier — then aged 24 — NSI Groupe (formerly Nette Services) is a professional cleaning specialist that has become a multi-services player: cleaning, green spaces, front-of-house services, pest control. Claiming the position of 21st-largest national player in the cleaning industry, the group is targeting the top 15 as early as 2026 and the top 10 in 2028.

Fourteen years in three phases

03. Analysis: the choices that make the difference

1. A clear and repeatable acquisition thesis

NSI focuses on acquisitions linked to the owner's retirement: healthy companies, a motivated seller, a transfer that can be prepared. Targets remain of a digestible size relative to the group, with one constant criterion: strengthening the national network or complementing a business line. This discipline avoids opportunistic deals that divert energy away from the plan.

This thesis breaks down into several different acquisition criteria depending on the strategy: there is not a single criterion of size, location or activity, but rather several combinations of these criteria, in order to reflect each strategy and the parallel development of organic growth.

These points form the cornerstone of the project's structuring.

2. Credibility as a deal-flow machine

After some twenty successful transactions, the group now regularly receives files from sellers. A reputation as a serious acquirer — one that integrates well, respects the teams and honours its commitments — becomes a competitive advantage in sourcing: the best targets come to you before they ever reach the market.

3. An ambitious and proactive project

NSI was not only approached by selling companies; it decided to map all the companies matching its criteria and to contact them in order to create opportunities. This proactive approach is at the heart of Collaboration Capital's project, which was thus able to create a constant pipeline of target companies and feed the project.

Beyond the volume, targeting off-market transactions made it possible to build privileged discussions with sellers, without competing against numerous buyers.

4. Integration built into a system

This is the most distinctive feature of the model. All employees joining the group — including those from acquisitions — go through the in-house training centre NSI Learn in Valenciennes, the company's birthplace: 1,750 learners in 2025, and a €1.5m investment in a new 700 m² building with technical training facilities. The group even purchased the Château d'Aubry-du-Hainaut to host employees on their induction journey and bring teams together. In a labour-intensive sector where value rests on contracts and teams, acculturation is not a luxury: it is the condition for retaining the acquired revenue.

5. Organic growth remains key

NSI continues to open its own branches and to diversify around its core business with subsidiaries created in-house — green spaces (NSI Green), front-of-house services (NSI Hospitality), cleaning of luxury boutiques (NSI Luxury) — to offer a comprehensive service. Acquisitions accelerate a machine that already works; they do not replace it.

04. The key takeaways — and the pitfalls to avoid

The NSI case is not reserved for mid-sized cleaning companies. The principles behind its success apply to any SME considering a build-up, whatever its sector.

05. Taking action: the method

1. 1

   Strategy and acquisition thesis.

   Clarify the objective (territories, business lines, critical mass), the target criteria and the financial capacity that can be mobilised.

2. 2

   Sourcing and approaching targets.

   Identify and qualify targets — including off-market — then approach their owners with discretion and method.

3. 3

   Analysis and valuation.

   Assess the target on the basis of the documents: financial performance, revenue recurrence, dependencies, realistic synergies, price range.

4. 4

   Structuring the financing.

   An acquisition is rarely financed from equity alone: senior bank debt, vendor loan, private debt, quasi-equity or opening up the capital. The right structure preserves cash and the ability to carry out the next transactions.

5. 5

   Negotiation, letter of intent, due diligence.

   Secure the agreement in an LOI, then audit — accounting, tax, social, legal — before any definitive commitment.

6. 6

   Closing and integration.

   Sign, then execute the integration plan prepared upstream: communication to teams and clients, harmonisation of processes, monitoring of synergies.

Collaboration Capital is an independent advisory firm specialising in mergers and acquisitions and financing transactions, registered with ORIAS as an intermediary in banking operations and payment services (IOBSP) under number 25000696 (www.orias.fr). This is a non-contractual document for educational purposes, prepared in September 2026 on the basis of public information relating to NSI Groupe (the group's own communications and regional business press) and public sector data (Fédération des entreprises de propreté, Bpifrance Création). Collaboration Capital was not involved in the NSI Groupe transactions cited as examples. A company's past performance is no guarantee of the results of an external growth strategy.