An Upbringing across Cultures
Antoine de Riedmatten grew up with an international outlook that had been part of his everyday life from the very beginning. “I was born in Algeria, and I spent 14 of my 16 first years in foreign countries (Algeria, Nigeria, Netherlands…) discovering new cultures as an expat,” he explains. Moving between countries during his formative years meant constantly adapting to new cultures and social environments, experiences that influenced him deeply, and that taught him valuable lessons that he still applies today. “Living abroad taught me that everyone is different and that you have to adapt to them to be efficient,” he reflects.
As a young student, he was naturally drawn to international matters and public affairs. “I chose political sciences and economy/finance as my dream was to become ambassador,” he remembers with a smile. The idea of representing his country abroad felt like a logical continuation of the international environment in which he had grown up. Yet, he ended up discovering that the world of professional services offered the same variety, the same need for adaptability, and more exposure to new situations. “I have always been very curious and I like new projects. professional services was made for me!”
His academic path reflects this interest, with a Master’s Degree in Auditing from Université Paris Dauphine – PSL, a Master’s in Public Policy Analysis from Sciences Po Bordeaux, and a Master’s in Accounting and Finance from Université de Bordeaux, along with his professional qualification as Chartered Accountant. Together, these studies provided both a broad strategic outlook and the technical expertise that would define the rest of his professional journey.
Early Career and Years at Deloitte
He began his professional career in 1987 at a 60-person accounting firm in Paris. “I started at a small accounting firm with prestigious clients who was acquired later by Deloitte in 1998,” he explains. Working in a relatively small structure meant being close to clients and involved in a wide range of tasks, an experience that would remain important to him later on. When the firm was integrated into Deloitte, he entered a much larger organisation, where the scope of responsibilities and the scale of operations were very different.
Over time, he took on a series of management and governance roles, including internal HR responsibilities and a position as Vice-Chairman of the Board of Directors of Deloitte in France. Each step brought new opportunities, and he approached them with a certain openness rather than waiting for perfect preparation. As he puts it, “I always accepted challenges, even when I was not fully a senior specialist on all dimensions of the new job.” This willingness to step into unfamiliar territory became a recurring theme throughout his career.
The Rise of In Extenso
During his time at Deloitte, he also became involved with In Extenso, a firm originally created within the group in 1991 to serve the SME market. The project had a clear purpose from the beginning. “In Extenso was created by Deloitte with the idea to reserve the Deloitte brand for large accounts and to set up a brand dedicated to small clients,” he explains.
The initiative grew out of a shared vision among several professionals who believed that small and medium-sized companies required a different approach, one that was closer to their day-to-day realities. Over time, the firm expanded steadily, bringing together offices across the country and gradually becoming the leading accounting services provider in France. By the time Antoine took on a more direct leadership role, In Extenso had already established a strong national presence and a clear identity of its own.
In September 2014, he became Managing Director of In Extenso. The appointment marked a new phase in his career, moving from senior roles within a large network to the leadership of a firm with its own trajectory and ambitions.
Independence and Transformation
Five years later, in April 2019, In Extenso’s partners elected him to head the Executive Board at a decisive moment, as the group moved toward independence from Deloitte. He recalls the transformation clearly: “At the time of In Extenso’s group creation as a spin-off of Deloitte, this business represented €10 million in revenue, which reached €400 million by 2019. Since becoming independent from Deloitte in 2019, the group has continued to grow steadily. We thus had the conditions to become independent, in terms of size, geographical network, maturity… In particular, we were large enough to be among the three largest players in the sector.”
The decision to separate from Deloitte was also closely linked to changes in the profession itself. “The conditions were right. And the trigger was that we’re in a period where investment is essential, whether for small or large clients. The digital revolution is affecting everyone. But in this context, investing in digital technology for our business wasn’t a priority for Deloitte, whereas for us, as In Extenso Partners, we had to act now, without waiting. This desire to have the necessary resources to invest and carry out our transformation was the catalyst,” he explains.
Partnering with ETL GLOBAL
Shortly after gaining independence, In Extenso took another strategic step by partnering with ETL GLOBAL in 2020. The initial contact came through a personal introduction that opened the door to further discussions. As Antoine de Riedmatten recalls, “My banker made the connection between Christian and myself.” The introduction was to Dr. Christian Gorny, CEO of ETL GLOBAL International, and the conversations that followed quickly revealed a strong affinity between the two organisations. Antoine highlights this alignment as based in “important similarities in terms of clients, structure, strategy, vision.”
The cooperation provided In Extenso with an international framework that suited its structure and entrepreneurial culture, while at the same time strengthening ETL GLOBAL’s presence in France through a dense national network and a strong position in the SME segment. Since then, In Extenso has continued its development beyond France, particularly in French-speaking markets such as Luxembourg, Belgium, and Switzerland, as well as in Spain, where its participation in the ETL French Desk supports French companies expanding into the region.
This partnership is also visible in ETL GLOBAL’s standing in France. In 2025, the network entered for the first time the International Accounting Bulletin’s French national rankings of international mid-tier professional services networks, taking the top position in the country in both fee income and staff count. A substantial share of this performance is driven by In Extenso, whose established national presence and strong market profile contribute decisively to ETL GLOBAL’s position in France, alongside the contribution of other member firms in the country, including Duthilleul & Associés.
Alongside its core professional services, In Extenso has also developed a visible presence beyond the accounting profession, particularly through its involvement in sports. The group became the title partner of the In Extenso Supersevens, a professional rugby sevens competition launched to bring a new format and a new audience to the sport, while also contributing to its long-term development.
For Antoine de Riedmatten, the initiative represented an opportunity to take part in a project that could be built from the ground up. “The Supersevens appeared to us as a unique opportunity to do things differently. When you create a new competition, it’s easier to change the rules of the game than in well-established sports where habits are deeply ingrained. From the outset, we wanted to make it a structuring project.”
Looking Ahead: the Profession of the Future
As the profession continues to evolve, Antoine de Riedmatten sees accounting moving well beyond its traditional focus on past figures. The role of the advisor, in his view, is increasingly centred on helping clients understand their present situation and prepare for what lies ahead. “Today, our focus is on the present, which means providing businesses with dashboards and management tools they can use day to day. That requires real-time accounting, and therefore strong digital capabilities. Once the present is clear, you can start working on the next stage: the future, with all its forecasting and planning.”
He describes this shift as a deeper transformation of the profession itself. “I use the word ‘reinvention’ because this used to be a profession mainly concerned with the past. Now we have to turn towards the present and the future. It’s by discussing those dimensions with our clients that the advisory role really comes into its own.”
In many ways, this conviction can be seen in the group’s recent initiatives, including their new brand identity launched in 2024, which reflects a broader positioning that speaks to the expectations of today’s entrepreneurs and to the changing nature of the profession. As Antoine explains: “Our new tagline, ‘Shape the future,’ expresses exactly where we want to go. We’re convinced the future offers real opportunities, and we want to help our clients seize them through entrepreneurship, digitalisation and innovation.”
A look back at ETL GLOBAL CONFERENCES
