What Thommessen does

Thommessen (legal entity Advokatfirmaet Thommessen AS) is a Norway-based full-service business law firm headquartered in Oslo, with additional offices in Bergen, Stavanger, and London. The firm advises large Norwegian and international corporations, financial institutions (banks, insurers, pension funds, securities firms), family offices and high-net-worth individuals, and public-sector clients across essentially the full breadth of commercial law — including M&A, banking and finance, competition and EU/EEA, capital markets, construction, tax, shipping and offshore, energy, technology, dispute resolution, sanctions, and procurement. Services are delivered through partner-led engagement on hourly, fixed-fee, or success-fee arrangements typical of large law firms, with client delivery supported by the "Thommessen Flow" secure client portal. Thommessen is a partner-owned private limited company under Norwegian law; Sverre Tyrhaug has been Managing Partner since 2013, and the firm is a member of the Lex Mundi global network for cross-border work. The firm operates an information security program certified to ISO 27001:2022. From a technology standpoint, Thommessen is a professional-services organization rather than a technology company: its only named digital product is the client portal, and there is no disclosed proprietary AI, data, or platform layer underpinning the business.

Name

Thommessen

Legal name

Advokatfirmaet Thommessen AS

Website

https://thommessen.no

Company type

Private

Founded year

1856

Operating status

Operating

Headcount range

501–1,000 employees

Short description

Thommessen is a Norway-based, partner-owned full-service business law firm advising large corporations, financial institutions, family offices, and public-sector clients across all commercial law areas from offices in Oslo, Bergen, Stavanger, and London.

Ownership category

akta.pro rank

Product category

Business Law Advisory Services

NAICS

Legal Services (5411), Offices of Lawyers (54111), Offices of Lawyers (541110)

SIC

Services-Legal Services (8111)

akta.pro primary industry

Family & Private Client (Trusts & Estates) Law (BPAHAAAK)

Keywords

• Corporate legal advisory
• Mergers and acquisitions
• Banking and finance law
• Competition and EU law
• Dispute resolution

Headquarters

HQ city

Oslo

HQ country

Norway

HQ region

Europe

Offices4 records

Markets served

GTM type

B2B

Offering type

Services

Cost components

Personnel, Operations, Technology or R&D, Marketing or Sales, Infrastructure

Revenue model

1. Legal Advisory Services: Thommessen generates revenue through providing legal advisory services to corporate clients across all commercial law areas. Services are billed based on hourly rates, fixed fees for specific matters, and potentially success fees for transaction-based work such as M&A.

Go-to-market motion1 record

Distribution channels1 record

Marketing channels5 records

Core offering

Thommessen is a full-service Norwegian business law firm providing strategic legal advisory to corporate clients across all commercial law areas, including M&A, banking and finance, capital markets, competition/EU-EEA law, construction, tax, shipping, energy, dispute resolution, and private wealth/family office work. Services are delivered by partners and specialist lawyers from offices in Oslo, Bergen, Stavanger, and London, with cross-border support via the Lex Mundi network. Clients access services and documents through the firm's secure Thommessen Flow client portal.

Product overview

Thommessen is a full-service Norwegian law firm offering a broad portfolio of legal advisory services across business law disciplines. The firm operates as a single integrated practice rather than a platform-plus-modules architecture, providing expertise in areas including M&A, banking and finance, competition law, construction (entreprise), dispute resolution, tax, shipping, energy, and technology law. Services are delivered through the Thommessen Flow client portal for secure client access.

Differentiator

Problem solved

Functional benefit

Products and services

• Legal Advisory Services Comprehensive legal advisory services across all business law practice areas for corporate clients, including M&A, banking and finance, capital markets, competition/EU-EEA law, construction, tax, shipping, energy, dispute resolution, and family office/private wealth.
• Thommessen Flow A secure online client portal that lets clients log in and access firm services, documents, and engagement information.

Segments4 records

Ideal customer profiles4 records

Technology focussed No

API detail

Has API

No

API docs

API detail

Core technology

AI maturity

App detail

Partnerships

One partnership is on record.

• Lex MundicoreStrategic or Co-development PartnerThommessen is a member of Lex Mundi, a global network of independent law firms. This membership enables Thommessen to provide legal services to clients with cross-border needs by connecting with member firms in over 100 countries worldwide.

Scale indicators2 records

Recent moves6 records

Expansion highlights5 records

Direct peers

• Advokatfirmaet Wiersholm: One of Norway's leading full-service business law firms based in Oslo, offering similar M&A, banking & finance, capital markets, and dispute resolution practices. Direct competitor for top-tier corporate mandates and also a Band 1/Tier 1 Chambers and Legal 500 ranked firm.
• Advokatfirmaet Schjødt: Premier Norwegian full-service law firm headquartered in Oslo with international offices, competing head-to-head with Thommessen for the largest M&A, finance, and energy mandates in Norway. Comparable headcount and similar Chambers/Legal 500 rankings.
• BAHR (formerly BA-HR): Leading Norwegian business law firm with a similar full-service model spanning M&A, banking, tax, and dispute resolution. Competes directly for major corporate and financial-sector mandates, with comparable peer rankings.
• Arntzen Grette: Major Norwegian full-service law firm specializing in corporate, energy, and public sector law. Notable as the firm Svein Terje Tveit left in 2025 to rejoin Thommessen — a direct head-to-head competitor for energy, competition, and public procurement mandates.
• Wikborg Rein: Norwegian-headquartered international law firm with offices in Oslo, Bergen, London, Singapore, and Shanghai. Competes with Thommessen in shipping, offshore, energy, and cross-border corporate work, and offers a broader international footprint.
• Advokatfirmaet Selmer: Oslo-based Norwegian law firm providing full-service corporate, tax, and dispute resolution advice. A mid-tier direct competitor for Norwegian corporate mandates, similar in geographic concentration though smaller than Thommessen.

Broad incumbents

• DLA Piper Norway: Global law firm with a Norwegian presence providing full-service corporate and finance advice. Competes for the largest cross-border mandates where a global platform is preferred over a domestic Norwegian firm.
• Clifford Chance Norway: Magic Circle firm with a Norwegian office serving large financial institutions and corporates on cross-border banking, capital markets, and M&A. Overlaps with Thommessen in Banking & Finance and Capital Markets for clients needing global coverage.
• Freshfields Norway: Magic Circle firm with growing Norwegian capability, competing for premium M&A and competition law mandates. Represents the international-firm competitive threat to top-tier Norwegian firms on cross-border matters.
• CMS Kluge: International law firm with a substantial Norwegian practice through Kluge (now CMS Kluge), offering corporate, energy, shipping, and dispute resolution services. Provides similar expertise as Thommessen with the backing of a global platform.

Market position

Strengths5 records

Weaknesses5 records

Competitive moat3 records

Key risks5 records

Key highlights7 records

Customer concentration

• Facebookfacebook.com/advokatfirmaetthommessen
• LinkedInlinkedin.com/company/31522
• Instagraminstagram.com/advokatfirmaet_thommessen

Compliance1 record

Revenue estimate

Valuation estimate

Number of profiles

Profiles10 records

Funding overview

Funding rounds

Investors

Funding detail is available on the Subscription and Enterprise plan.Contact sales →

M&A

Investments

M&A and investment is available on the Subscription and Enterprise plan.Contact sales →

Frequently asked questions about Thommessen