Grant Thornton Advisors to acquire Stax

• Together will serve almost 70% of US-based Private Equity International 300

Grant Thornton Advisors LLC (GTA) on Tuesday said it will acquire Boston-based Stax, a strategy consulting firm specialising in commercial due diligence, value creation, and exit-planning services for private equity (PE) firms, as well as their portfolio companies and advisers. 

Stax provides buy- and sell-side diligence and planning for merger and acquisition (M&A) activities, while delivering clients with growth strategies and value-creation initiatives. 

The firm’s data-driven approach taps into leading Artificial Intelligence (AI) and advanced intelligence to deliver actionable insights and proven successes for its clients, GTA said in a statement. 

“The three-decade-old firm has grown rapidly in recent years, while maintaining high client-retention rates and lengthy stakeholder relationships. It serves many of the leading players in large-cap and middle-market PE, alternative investments, and investment banking,” it said. 

The acquisition will elevate US-headquartered GTA’s market-leading transaction advisory team by enhancing the breadth and depth of its M&A capabilities. 

The practice said it currently has more than 600 PE relationships, including 60% of the top 10 global PE firms by total equity, and more than 1,600 sponsor-backed clients. The deal with Stax further expands GTA’s commercial-diligence offerings and adds Stax’s seasoned transaction-consulting leadership team and entrepreneurial energy. Together, the two firms will service almost 70% of the US-based Private Equity International 300. 

The transaction grows the multinational, multi-disciplinary platform that GTA established in January 2025. To date, it has announced transactions with several accounting and consulting firms to join the platform, including those in Ireland, the United Arab Emirates (UAE), Switzerland/Liechtenstein, the Netherlands, Luxembourg, the Cayman Islands, and the Channel Islands. 

Additionally, GTA announced a deal last month to acquire Auxis, a US-based leader and pioneer in outsourcing and business-modernisation services. The platform is backed by an investor group led by New Mountain Capital, a growth-oriented investment firm with approximately $ 55 billion in assets under management.

“With this bold move, we’re taking our platform to new heights, combining Stax’s top-tier talent with our own industry-leading professionals, while broadening our offerings and further elevating our tech capabilities,” said Grant Thornton Advisors CEO Jim Peko. “Stax has a decades-long legacy delivering transformative value to clients, similar to our own 100-year history. Together, we will generate bold results for a PE client base stretching from the Americas across Europe to the Middle East.” 

“PE firms today don’t just want an adviser; they want a partner with agility, intelligence, and scale,” said Grant Thornton Advisors Managing Partner for Advisory Services Tom Puthiyamadam. “By adding Stax, we’re combining trust with data-driven precision to unlock strategic value at every stage of the investment lifecycle. This is more than an expansion—it’s a leap forward in delivering outcomes for PE and corporate clients.” 

Stax CEO Jayson Traxler said: “We are proud to have built a 30-year reputation for excellent client service, unique tech-enabled solutions, and impressive growth. As part of Grant Thornton Advisors, those characteristics will endure—but with far greater scale, speed, and amplification of our impact. We will be empowered to build on our unique strengths and insights, for the benefit of the leading PE firms, portfolio companies, and investment banks.” 

Stax’s approximately 300 team members will join Grant Thornton Advisors when the transaction closes, which is expected to take place in 2025, subject to standard closing conditions. 

New Mountain Capital Managing Directors Andre Moura and Nikhil Devulapalli said: “Stax’s world-class commercial diligence and value-creation capabilities are highly complementary to Grant Thornton Advisors’ scaled transaction advisory offering. The addition of Stax enables Grant Thornton to better serve its clients as they contemplate and execute on major investment decisions and operating initiatives. We are proud to continue supporting Grant Thornton as the firm grows and broadens its capabilities.”

In addition to transaction-related services, Grant Thornton Advisors provides a range of services centred on strategy, transformation, and operations. These include offerings across technology, finance, operations, sales and marketing, data, AI, cybersecurity, and risk. It also provides a complete slate of tax services.

Clearsight Advisors, Inc. and Harris Williams served as financial advisers to Grant Thornton Advisors — and its legal adviser was Simpson Thacher & Bartlett LLP. William Blair served as financial adviser to Stax. Jones Day served as legal adviser to Stax. Stout served as sell-side financial diligence and tax adviser to Stax.