Top-ranked
Our high standards of professional excellence are confirmed by reputable rating agencies and various law firm reviews.







Leading transaction firm
Our transaction practice includes both large and complex transactions, and a large number of transactions involving small and medium-sized businesses. The combination provides in-depth expertise and workability. Thommessen’s practice within mergers and acquisitions (M&A) and equity market transactions (ECM) has been the market leader for many years, in terms of both the number of transactions and/or in market value.
M&A
Source: Mergermarket League Tables, Legal 01.01.2005–01.04.2026
ECM/IPO
Source: Dealogic Top 10 IPO Issuer and Manager Attorney League Table (Oslo Axess, Oslo Børs and Euronext Growth) 01.01.2005–01.04.2026
Testimonials

Thommessen provides a service that is compassionate and understanding to our needs. It really cares about its clients and our success.
Client quote – Chambers and Partners, 2025

Thommessen has good lawyers across a wide range of areas, which makes them the leading one-stop shop for transactions.
Client quote – Legal 500, 2025

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.
Client quote – IFLR1000, 2025

The preferred choice when
understanding your business
matters