Since 1978, we have continuously built our authority and reputation as an international business law practice. Growing from a small tax law boutique to a full service commercial law firm has been quite an adventure. We look forward to the years to come!
Client Endorsements and Industry Recognition
Maintaining our clients' continued trust by delivering measurable results is what is most important to us.
Yet, we are of course also pleased when the quality of our service is recognized publicly. Here is some of the recognition we have gratefully received from clients and peers in recent years.
“We were very pleased with the fast and pragmatic definition and implementation of our legal setup including our stock option plan. Thierry Thormann, Luzi Cavelti and their teams were very responsive, client-oriented and results-driven, which distinguished them from other legal partners we worked with.”
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“Our company produces various chemicals that are being sold globally. Having a dispute with our Chinese partners, we were forced to go down the path of arbitration in Switzerland. For legal assistance, we chose Altenburger, in particular Dr. Clarisse v Wunschheim and her colleagues.
From the very beginning throughout the whole process she gave us deep insights into “Chinese thinking”, various options to keep the channels of communication open, a perfect balance between deterrence and reward.
We would have struggled without her competence, hard work and her goal-oriented approach.
Not only all the legal aspects got brilliantly covered, but also business aspects that we would not have considered, helped us back on to the road for a fruitful relationship with our Chinese partners. I can fully recommend Clarisse, her team and Altenburger!”

Our firm and our lawyers regularly rank in independent directories. A selection of these achievements can be found below.
Altenburger is recognized by Bilanz Magazine and PME in the following practice areas:
- General Contract Law
- Employment Law (Employer Side)
- Compliance
- Mergers and Acquisitions (M&A) (more than 50 employees)
- Corporate Law (more than 50 employees)
- Real Estate Law
- Media Law
- Private Equity and Venture Capital
- Restructuring and Insolvency Law
- Tax Law and Duties
We are proud to share that Altenburger has been recognized in the Legal 500 Europe, Middle East & Africa 2026 rankings in:
- Commercial, corporate and M&A
- Employment
Congratulations to the entire team!
We are proud to share that Altenburger has been recognized in the Chambers and Partners Global Guide 2026
Firm Ranking:
Lawyers’ Ranking
Arbitrators: Clarisse von Wunschheim
Mediators: Birgit Sambeth
Corporate and M&A: Thierry Thormann
The following Altenburger team members feature on “Lexology Index 2026”:
- Clarisse von Wunschheim – National Leader – Switzerland – Arbitration
- Birgit Sambeth - National Leader – Switzerland – Commercial Mediation and Restructuring & Insolvency
- Luzius Cavelti - National Leader – Switzerland – Corporate Tax
- Thierry Thormann - National Leader – Switzerland – M&A
- Leonard Toenz - National Leader – Switzerland – Insurance & Reinsurance
Altenburger is recognized by Bilanz Magazine & Le Temps in the following practice areas:
- Tax
- General Contract Law
- Banking/Finance
- Private Equity and Venture Capital
- Employment Law (Employer's Side)
- Restructuring and Insolvency Law
- Compliance
Bilanz-Rating: Die besten Anwälte und Anwaltskanzleien der Schweiz 2025 | BILANZ
Noted as a ‘highly skilled, fast and pragmatic’ team, ALTENBURGER LTD legal + tax maintains a varied practice, extending from private equity deals to corporate reorganisations. Thierry Thormann and Massimo Calderan head up the group; the former is well-versed in M&A, restructuring, and corporate finance mandates, while the latter specialises in cross-border issues between Switzerland and Italy.
Manuel Moor is also recommended.
The following Altenburger team members feature on “Lexology Index 2025”:
- Clarisse von Wunschheim – National Leader – Switzerland – Arbitration 2025
- Birgit Sambeth - Global Elite Thought Leader in Commercial Mediation 2025 - Restructuring & Insolvency 2025
- Leonard Toenz - National and Global Leader – Switzerland – Insurance 2025
- Thierry Thormann - National Leader - Switzerland - M&A 2025
- Luzius Cavelti - National Leader - Switzerland - Corporate Tax 2025
Altenburger is recognized by Bilanz Magazine & Le Temps in the following practice areas:
- Tax
- M&A
- Banking/Finance
- Private Equity
- Corporate
- International Law
- General Contract Law
- Employment Law (Employer's Side)
The following Altenburger team members feature on “Lexology Index" (former) Who's Who Legal:
- Clarisse von Wunschheim – Global Leader Arbitration 2024 / National Leader – Switzerland – Arbitration 2024
- Luzius Cavelti – Switzerland – Corporate Tax 2024
- Birgit Sambeth - Switzerland - Commercial Mediation 2024 and Restructuring & Insolvency
Altenburger has been ranked in the Best Law Firm rankings 2024 of Leaders League Switzerland in the following practices areas:
- Clarisse von Wunschheim - Aline Wey Speirs - Birgit Sambeth (Dispute resolution - International arbitration)
- Birgit Sambeth (Restructuring & Insolvency)
- Massimo Calderan (Corporate and M&A)
- Luzius Cavelti and Leonard Toenz (Corporate Tax)
The following Altenburger team members feature on “Who's Who Legal”:
- Birgit Sambeth– Thought Leader Mediation 2023 / National Leader – Switzerland – Commercial Mediation and Restructuring & Insolvency 2023
- Clarisse von Wunschheim – Global Leader Arbitration 2023 / National Leader – Switzerland – Arbitration 2023
- Luzius Cavelti – Switzerland – Corporate Tax 2023
Law Firm of the year Arbitration
"During the last 12 months the professionals have been involved in relevant international matters distinguishing themselves for the pragmatic approach and negotiation skills."
Altenburger is recognized by Bilanz Magazine & Le Temps in the following practice areas:
Best Practice Finance & Fintech
"A team made up of experienced professionals able to tackle issues of any degree of complexity. They continue to reconfirm themselves as one of the most acclaimed firms, providing assistance to some of the main operators in the financial sector."
Lawyer of the Year – Dispute Resolution: Birgit Sambeth
"Appreciated by the market for the experience and in-depth knowledge of arbitration matters. The professional is to all intents and purposes one of the icons in her field."
Altenburger has been ranked in the Best Law Firm rankings 2023 of Leaders League Switzerland in the following practices areas:
- Birgit Sambeth (Restructuring & Insolvency)
- Massimo Calderan (Corporate and M&A)
- Luzius Cavelti and Leonard Toenz (Corporate Tax)
The following Altenburger team members feature on “Who's Who Legal”:
- Birgit Sambeth– Thought Leader Mediation 2022 / National Leader – Switzerland – Mediation and Restructuring & Insolvency 2022
- Clarisse von Wunschheim – Global Leader Arbitration 2023 / Thought Leader Arbitration 2022 / Global Leader Arbitration 2022 / National Leader – Switzerland – Arbitration 2022
- Luzius Cavelti – Switzerland – Corporate Tax 2022
Altenburger is recognized by Bilanz Magazine & Le Temps in the following practice areas:
Contact
Geneva
Altenburger Ltd legal + tax
Rue Rodolphe-Toepffer 11bis
1206 Geneva
Lugano
Altenburger Ltd legal + tax
Via P. Lucchini 7
6900 Lugano
Zurich
Altenburger Ltd legal + tax
Seestrasse 39
8700 Küsnacht-Zurich