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Guy Deillon

Associated Partner

Position: Partner , Associated Partner
Practice Areas: Banking & Finance , Capital Markets , Corporate & M&A , Venture Capital
Field-Display: Banking & Finance Team , Capital Markets Team , Corporate & M&A Team , Venture Capital Team , Startups

Guy Deillon focuses on domestic and international mergers and acquisitions as well as private equity transactions. Further, he assists companies in financings as well as on general corporate, stock exchange and capital markets law matters.

Guy Deillon's clients benefit from his strong focus on goals and results as well as his high sense of responsibility. His analytical strength and logical approach support his focus on the business perspective and problem solving. He always demonstrates a clear and distinct position in a diplomatic and collaborative spirit.


+41 44 254 55 55



Admission to the Bar

Admitted in Switzerland (2011) 

Practice Areas

  • Corporate & M&A
  • Venture Capital
  • Capital Markets


  • Columbia Law School (LL.M., 2018)
  • University of Fribourg, Humboldt University of Berlin (MLaw, 2008)


  • French
  • German
  • English


  • Zurich and Swiss Bar Association
  • Swiss Private Equity & Corporate Finance Association
  • Swiss LegalTech Association


Melanie Cica
+41 44 254 55 15

Monika Bren
+41 44 254 55 48

Pragmatic, efficient and smart. — The Legal 500 Switzerland 2024

We have great collaboration and I feel like more than just a client. I can call Guy Deillon at any time and he always manages to find time to provide his advice, which is highly appreciated and valuable. I really appreciate the support and how we communicate. I can count on his quality advice and rapid responses. — The Legal 500 Switzerland 2024

Guy Deillon is an amazing corporate and M&A lawyer. — The Legal 500 Switzerland 2023


Subject: Corporate & M&A
Autor: Guy Deillon
Reading time: 3 Min

Current M&A challenges

As interest rates have risen, the number of M&A transactions has fallen. In the first edition of the "Legal Success" supplement to the journal Finanz und Wirtschaft, our associated partner Guy Deillon answers a number of questions relating to the rise in interest rates and its impact on M&A transactions.

Subject: Corporate & M&A
Autor: Guy Deillon
Paper: NZZ
Reading time: 4 Min

How woke do companies need to be?

In Switzerland, too, corporate bodies are increasingly being pressurised to position themselves - and this is often criticised

The hashtag used by thousands of spiteful bloggers to criticise managers who pla...

Label: Highlight
Subject: Banking & Finance, Corporate & M&A, Insolvency & Restructuring
Autor: Daniel Hayek, Laura Oegerli, Guy Deillon, Anik S. Zehnder
Reading time: 1 Min

Prager Dreifuss Advises Investment Fund Attestor on EUR 450m Facility

Prager Dreifuss advised investment fund Attestor in relation to a complex, innov...

Subject: Corporate & M&A
Autor: Guy Deillon
Reading time: 1 Min

Securing your Legacy: Best Practices for a Successful Exit and the Life Afterweard

On the topic of exit strategy, the Zurich Chapter of the Entrepreneur's Organization hosted an exciting and worthwhile panel discussion for its members on May 11 at the offices of Bank Pictet. Our Associated Partner Guy Deillon represented Prager Dreifuss on the panel and provided information on the specific legal situation, including due diligence.

Next to him, experienced exiteers gave information about their cases: Elian Kool, Co-Founder of Netcentric (Exit 2017 to Cognizant) and Andy Schwarzenbach, Co-Founder of HITZBERGER (Exit 2017 to Migros). Jeremias Meier, Founder of Bexio AG (Exit 2018 to Mobiliar) moderated the subsequent discussion. Christian Binz from Pictet Wealth Management contributed the banking and investment perspective.

Subject: Health and Medical Law
Autor: Andrea Schütz, Guy Deillon

Peut-on encore planifier la succession médicale?

Admission AOS En raison des nouvelles restrictions d’admission des médecins, il devient plus difficile de reprendre un cabinet médical. Qui souhaite acheter ou vendre un cabinet ne devrait pas régler le transfert du numéro RCC, mais celui de l’admission AOS. Il appartient aux cantons de décider si et comment les admissions AOS peuvent être transférées. Un aperçu de la situation juridique actuelle.


Subject: Banking & Finance
Autor: Christian Schönfeld, Guy Deillon
Paper: NZZ
Reading time: 4 Min

Need for instruments against a bank run

An American law professor makes a proposal on how a withdrawal in panic of bank deposits could be curbed

With the fall of Credit Suisse, a new term emerged in the public opinion - "bank...

Subject: Banking & Finance
Autor: Daniel Hayek, Guy Deillon

Open questions in connection with the takeover of Credit Suisse by UBS

On the evening of 19 March 2023, the Federal Council, accompanied by representatives of the Swiss National Bank and the Swiss Financial Market Supervisory Authority (FINMA), as well as the respective chairmen of the boards of directors of UBS and Credit Suisse, announced the takeover of Credit Suisse by UBS in the form of a statutory merger of the two entities, with a merger ratio of 22.48 Credit Suisse shares to 1 UBS share.

The Federal Council has taken two important decisions under emergency law (Art. 184 para. 3 and Art. 185 para. 3 of the Swiss Constitution), which deviate from existing federal law. The first, which has been widely publicized, is the suppression of the rights of the shareholders of Credit Suisse and UBS to approve the merger. The second, which initially went unnoticed, is the full write-off of additional equity capital (AT1) of Credit Suisse in the amount of 16 billion Swiss francs.

These decisions, along with other measures to stabilize the markets, were published in the Official Compilation of Swiss Laws on 20 March 2023 in a so-called Ordinance on additional liquidity assistance loans and the provision of default risk guarantees by the Confederation for liquidity assistance loans from the Swiss National Bank to systemically important banks (hereinafter the CS-UBS Ordinance), and an explanatory report was published by the Federal Council.

Write-off of Additional Equity Capital (AT1)

According to the Capital Adequac...

Subject: Banking & Finance
Autor: Guy Deillon
Paper: IFLR

IFLR: Developments in the management of climate risks in Switzerland

FINMA has recently issued new guidance, FINMA Guidance 01/2023, drawing attention to relevant developments in the area of climate-related financial risk management. In the Guidance, FINMA reiterates its expectation for financial institutions to establish an appropriate climate risk management framework based on recognised practices. Guy Deillon of Prager Dreifuss considers the new FINMA Guidance and its impact on financial institutions.

Label: Highlight
Subject: Corporate & M&A
Autor: Guy Deillon
Paper: NZZ
Reading time: 3 Min

Company succession and Generation Z

Sale to a private equity fund should be considered in succession planning.

From the Middle Ages until the middle of the 19th century, succession was govern...

Autor: Guy Deillon

Transfer of private bank client portfolios

Banks are now facing major challenges. Once the uncertainties related to the US program are resolved, a new wave of restructuring is expected. While large banks may be interested in acquiring new portfolios, it is mainly the small and medium-sized private banks that will have to fundamentally rethink their business model in order to maintain their profitability.

To the publication