The €250 Million Buy-and-Build Machine

The weird part of Sia's acquisition of Seven Consulting is that Sia is a boutique French consulting firm — the sort of company that was supposed to stay small, independent, and founder-run. The sort of company whose business is selling its independence as a feature. And now it has a private equity firm buying the other side of the table, a defined M&A playbook, and a pipeline of acquisitions that reads less like boutique consulting and more like a bolt-on roll-up.

Sia, a Paris-based management and AI consulting group, announced today that it has acquired Seven Consulting, an Australian management consulting firm, an Australian program management firm founded in 2002 with more than 100 consultants. Seven manages over $4 billion in transformation programs and counts National Australia Bank, Macquarie, ASX, the Australian government, Woolworths, Coles, and AGL among its clients. Its team is split between Sydney, Melbourne, and Manila.

On the surface, this is a geographic expansion. Sia already had a foothold in Australia — it bought Churchill Consulting, a Perth firm of about 45 consultants generating roughly AUD 14 million in annual revenue, back in 2022. Adding Seven gives Sia flagship offices on the East Coast and brings the combined Australian team to around 130 consultants. The press release says the goal is to reach "critical mass" in the country.

But the frame that actually explains the deal isn't geography. It's capital structure.

In December 2024, Blackstone injected up to €250 million into Sia for a minority stake. That was Sia's first partnership with a financial investor in its entire 27-year history. The press release at the time was clear: the money was designated to support M&A alongside organic growth. Sia's founder and CEO Matthieu Courtecuisse kept a significant majority stake, but the growth engine changed. The firm that had funded every one of its prior acquisitions entirely from operating reserves now had a balance sheet with private equity backing.

And since that December deal, the acquisition cadence has been steady. Kaiser Associates, a Washington DC-based strategy consultancy founded in 1981, was acquired in January 2026. Now Seven Consulting. Two bolt-ons in eight months after Blackstone's check cleared.

This is basically a buy-and-build strategy in a space where buy-and-build used to be unthinkable. Consulting firms don't typically have private equity behind them. The classic model — McKinsey, BCG, Bain — is partnership-owned, profit-sharing, deliberately slow to grow, and fiercely protective of its culture. The Big Four grew into scale over decades of organic recruitment and merger. The boutiques stayed small because the business model rewards high billable rates and partner loyalty, not headcount.

Sia's model is different, even before Blackstone. Founded in 1999, Sia has always been more acquisitive than the traditional boutiques. It has made more than 20 acquisitions since 2008, building out capabilities in cybersecurity, blockchain, life sciences, and now AI — it claims roughly 450 data and AI specialists internally, has launched generative AI tools called SiaGPT, and touts partnerships with AWS and NVIDIA. Sia generates close to €500 million in annual revenue and employs around 3,000 people across 48 offices in 19 countries.

But the Blackstone money changes the incentives. Blackstone doesn't own Sia. It is a minority shareholder. That means it can't dictate strategy or force an exit timeline. But minority stakes in operating companies typically come with board rights, information access, and a shared interest in scaling the thing that will eventually be valued — whether that means a future majority sale, a public offering, or simply a higher-percentage return on a smaller slice.

The simplest model is this: Blackstone wants Sia to get bigger and more consolidated so that its minority stake becomes more valuable. The fastest way to grow a consulting firm by revenue is to buy other consulting firms. Revenue per employee in consulting is a sticky metric — Sia reportedly pulls in roughly $308,000 per employee — so headcount is a reliable proxy for revenue growth. Buy a firm with 100 consultants, and you get approximately $30 million in annual revenue. That is how you accelerate growth without proving your organic pipeline first.

Seven Consulting fits this pattern cleanly. It has the client relationships (blue-chip Australian banks, government, major retailers), the team (100+ consultants), the revenue base, and the niche (program delivery and change management — the part of consulting that happens after the strategy deck is done and someone actually has to execute). Sia brings the brand, the AI playbooks, the global network, and the capital. Seven brings the entrenched Australian relationships Sia would otherwise have to build from scratch.

There's also a product-angle component. Sia says the combined entity will become a leading "AI transformation partner" in Australia, moving clients from experimentation to enterprise-scale deployment. That's a real gap in the Australian market. Big clients have been running pilot AI projects for years and need program managers who understand both the technology and the organizational change required to scale it. Seven has the program management; Sia has the AI specialists. Together they're trying to own the in-between.

Now, the question any reader should have is whether this model is sustainable. Buy-and-build in consulting carries a hidden cost: cultural dilution. The product of a consulting firm is the trust between its consultants and its clients. You can buy a team and a client list, but the relationships are sticky to the people, not the PowerPoint deck. When a boutique founder sells to a larger firm, some key people stay, some leave to start their own practice, and some clients quietly shop for alternatives.

Sia's track record on this is decent. Churchill in Perth appears to have integrated without fanfare. The firm has made dozens of acquisitions over the past decade without an obvious public casualty. But the Blackstone-funded phase of Sia's growth hasn't been running long enough to judge whether the buy-and-build cadence is creating value or just inflating revenue. Revenue growth from acquisitions is easy. Margin expansion after acquisitions is harder. And the difference between the two is where a private equity return either compounds or evaporates.

What we don't know — and Sia hasn't disclosed — is the purchase price for Seven, whether Seven's founder Declan Boylan and managing director Gareth James stayed with equity, and what Blackstone's minority stake now represents in percentage terms after the capital injection. Those are the details that tell you who is actually capturing the upside.

But we can say something about the machine. A French boutique consulting firm that once funded its own growth is now executing a private-equity-backed acquisition strategy in the consulting sector — a sector that was supposed to be immune to that model. Blackstone has the minority piece of Sia and wants it to get bigger. Sia wants to be a global AI consulting platform. Seven Consulting wanted an exit from its founder and a path to something larger than the Australian boutique market.

Everybody's incentive is aligned. The only question that's not answered is whether "bigger" in consulting is the same thing as "better," or whether the buy-and-build model eventually runs into the problem that the consulting business is measured in people hours and trust, not widgets and distribution.

The structural implication is simple: if Sia's model works, the boutique consulting sector — which has been an island of independence for decades — is about to look a lot more like a PE roll-up market. And if it doesn't, the €250 million Blackstone put in will be the interesting case study in what happens when you try to apply industrial consolidation logic to a business that sells relationships.