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Key contacts
Managing Partner: Sverre Tyrhaug
Partner: Hans Haugstad
Partner: Lars Eirik Gåseide Røsås
Partner: Hans Cappelen Arnesen
Quick facts
Number of lawyers

275

Number of partners

63

Network memberships

Lex Mundi

Languages

Norwegian, Danish, Swedish, English, Dutch, German, French

Key practice areas
Banking and finance
Capital markets
Capital markets : Debt
Capital markets : Equity
Financial and corporate
M&A
Energy and infrastructure
Project development
Firm overview

Established in 1856, Thommessen is considered to be one of Norway’s leading commercial law firms. The firm has offices in Oslo, Bergen, Stavanger and London. The firm provides advice to Norwegian and international companies as well as organisations in the public and private sectors, ranging from SMEs to large multi-national corporations. Thommessen covers all business related fields of law.

Thommessen assists businesses with transactions, complex projects and contentious matters in all areas of commercial law. Their robust professional legal expertise is combined with in-depth industry knowledge, and their lawyers stay abreast of trends and developments on an ongoing basis in order to provide advice which facilitates long-term value creation.

Key transactional practices
  • Banking and finance
  • Capital markets
  • Competition/antitrust
  • Construction
  • Corporate and M&A
  • Dispute resolution
  • Regulatory
  • Intellectual property
  • Labour and employment
  • Investment funds
  • Private equity
  • Restructuring and insolvency
  • Tax
Address:
Ruseløkkveien 38
0251 Oslo
PO Box: Postboks 1484 Vika
Tel:+47 2311 1111 Fax:+47 2311 1010 Email:Contact Us Web Address:http://www.thommessen.no/en/
Rankings published in 2026
Banking and finance
Tier 1
14 firms ranked
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Tier 1

BAHR
8 practice areas
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Thommessen
8 practice areas
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Wiersholm
8 practice areas
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Wikborg Rein
7 practice areas
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Tier 2

Arntzen Grette
8 practice areas
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Schjødt
8 practice areas
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Simonsen Vogt Wiig
8 practice areas
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Tier 3

Haavind
8 practice areas
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Selmer
8 practice areas
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Tier 4

CLP
8 practice areas
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CMS Kluge
6 practice areas
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DLA Piper
3 practice areas
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SANDS
7 practice areas
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Notable

Kvale
4 practice areas
View profile
Capital markets : Debt
Tier 1
10 firms ranked
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Tier 1

BAHR
8 practice areas
View full profile
Thommessen
8 practice areas
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Wiersholm
8 practice areas
View full profile
Wikborg Rein
7 practice areas
View full profile

Tier 2

Arntzen Grette
8 practice areas
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Schjødt
8 practice areas
View profile

Tier 3

Selmer
8 practice areas
View profile
Simonsen Vogt Wiig
8 practice areas
View full profile

Notable

Haavind
8 practice areas
View full profile
SANDS
7 practice areas
View full profile
Capital markets : Equity
Tier 1
12 firms ranked
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Tier 1

BAHR
8 practice areas
View full profile
Schjødt
8 practice areas
View profile
Thommessen
8 practice areas
View full profile
Wiersholm
8 practice areas
View full profile
Wikborg Rein
7 practice areas
View full profile

Tier 2

CLP
8 practice areas
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Haavind
8 practice areas
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Selmer
8 practice areas
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Simonsen Vogt Wiig
8 practice areas
View full profile

Tier 3

Arntzen Grette
8 practice areas
View profile

Notable

AGP Advokater
3 practice areas
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SANDS
7 practice areas
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M&A
Tier 1
16 firms ranked
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Tier 1

BAHR
8 practice areas
View full profile
Schjødt
8 practice areas
View profile
Thommessen
8 practice areas
View full profile
Wiersholm
8 practice areas
View full profile
Wikborg Rein
7 practice areas
View full profile

Tier 2

CLP
8 practice areas
View profile
Haavind
8 practice areas
View full profile
Selmer
8 practice areas
View profile

Tier 3

Arntzen Grette
8 practice areas
View profile
DLA Piper
3 practice areas
View profile
Simonsen Vogt Wiig
8 practice areas
View full profile

Tier 4

AGP Advokater
3 practice areas
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Aabø-Evensen & Co
7 practice areas
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CMS Kluge
6 practice areas
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SANDS
7 practice areas
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Notable

Kvale
4 practice areas
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Project development
Tier 1
13 firms ranked
View full list

Tier 1

BAHR
8 practice areas
View full profile
Haavind
8 practice areas
View full profile
Schjødt
8 practice areas
View profile
Thommessen
8 practice areas
View full profile
Wiersholm
8 practice areas
View full profile
Wikborg Rein
7 practice areas
View full profile

Tier 2

Arntzen Grette
8 practice areas
View profile
CMS Kluge
6 practice areas
View profile
Selmer
8 practice areas
View profile
Simonsen Vogt Wiig
8 practice areas
View full profile

Tier 3

CLP
8 practice areas
View profile
Kvale
4 practice areas
View profile
Lund & Co
2 practice areas
View profile
Linked Reviews
Financial and corporate

Thommessen is a leading Norwegian law firm with offices in Oslo, Bergen, Stavanger and London. The firm’s history stretches back to 1856. The firm is highly ranked across all areas of financial and corporate law. The firm has a strong focus in banking, technology and renewable energy.

 

Highlights

A significant highlight of the firms activity during the research period includes advising Public Property ASA (PPI) on a major transaction to acquire a portfolio of industrial infrastructure assets from TRG Real Estate for NOK 2.325 billion. The firm provided advice to PPI in connection with the acquisition and the subsequent joint venture involving Resource Group TRG.  

Another notable highlight includes the firm providing legal and strategic advice to Holmaneset H2 AS in connection with the development of hydrogen facility. Partner, June Snemyr is involved in advising on the projects decarbonization effort and its construction.  

 

Testimonials 2025

Thommessen's lawyers are extremely competent and highly specialized. They bring in-depth knowledge of regulatory nuances and market practices that help anticipate and mitigate risks early.” - Bank lending  

 

Thommessen delivers high quality services and can put together knowledgeable and skilled teams.” - Bank lending  

 

“They deliver a broad range of services which covers most of our needs for legal assistance. The teams consist of leading lawyers in the Norwegian market” - Banking and finance 

 

“Good commercial insights, always available and pragmatic. Not spending long time on smaller "irrelevant" matters as other lawyers just to bill more hours” - Capital markets equity  

 

“Highly knowledgeable, meets deadlines, offers great expertise within small scale hydro power” - M&A 

 

“Very professional - also the brilliant understanding of the business (additional to the pure legal view of things)” - Project development 

 

 

Key clients

 

Fortescue Future Industries International, Klimapark Nees Hede/Cloudberry, Heidelberg Materials, Northern Lights, Akershus Energi, Altor Equity Partners, Triton Partners, Ferd, HitecVision, Norvestor, DOF Group, XXL, Goldman Sachs, ABG Sundal Collier, Arctic Securities, DNB Bank ASA, Nordea Bank, Danske Bank, Svenska Handelsbanken, Skandinaviska Enskilda Banken AB 

21 results21 results
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Deal Highlights
54 results54 results
Deal Name Deal Date Firm Name Jurisdiction Deal Type Lawyer Names Client Names Client Role
Green Investment Group - Project development
2022-02-24
Thommessen
Norway
Project development
Bendik Christoffersen
Green Investment Group
Project developer
Glastad Farsund AS - Project development
2022-02-24
Thommessen
Norway
Project development
Jacob F Bull
Glastad Farsund AS
Project developer
FREYR AS - Project development
2022-02-24
Thommessen
Norway
Project development
Jacob F Bull
FREYR AS
Project developer
Fearnley Securities and Pareto Securities - IPO
2022-01-15
Thommessen
Norway
IPO
Lars Eirik Gåseide Røsås
Fearnley Securities and Pareto Securities
Underwriter
Arctic Securities, DNB Markets, SpareBank 1 Markets - IPO
2022-02-24
Thommessen
Norway
IPO
Solveig Fagerheim Bugge
Arctic Securities, DNB Markets, SpareBank 1 Markets
Underwriter
Altia plc - M&A
2022-02-24
Thommessen
Norway
M&A
Solveig Bugge
Altia plc
Merger party
Clarksons Platou Securities - Bond issue
2022-01-07
Thommessen
Norway
Bond issue
Halvor Mansåker
Clarksons Platou Securities
Underwriter
DNB Markets; Danske Bank - Bond issue
2022-02-14
Thommessen
Norway
Bond issue
Einar Grette
DNB Markets, Danske Bank
Underwriter
Småkraft AS - Bond issue
2022-02-24
Thommessen
Norway
Bond issue
Bendik Christoffersen and Einar Grette
Småkraft AS
Issuer
NTS AS - M&A
2023-06-05
Thommessen
Norway
M&A
NTS AS
Seller
Cadeler A/S - M&A
2023-06-16
Thommessen
Monaco
M&A
Cadeler A/S
Buyer
Kahoot! ASA - M&A
2023-07-14
Thommessen
Norway
M&A
Kahoot! ASA
Target
Carel Industries SpA - M&A
2023-07-24
Thommessen
Norway
M&A
Carel Industries SpA
Buyer
eBay Inc. - M&A
2023-11-21
Thommessen
Norway
M&A
eBay Inc.
Seller
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