Allen & Overy Belfast in mega merger with US firm

Move creates first fully integrated global elite law firm with revenues of nearly £3 billion

The Allen & Overy Belfast office
Allen & Overy, which employs more than 700 people at its Belfast office on Donegall Quay, has merged with US firm Shearman & Sterling

Law firm Allen & Overy, which employs more than 700 people in Northern Ireland, has merged with US outfit Shearman & Sterling to create a new Magic Circle mega-firm.

The newly established firm - to be known as A&O Shearman - comprises nearly 4,000 lawyers including 800 partners across 47 offices in 29 countries, with a combined annual revenue of close to £3 billion.

The firms first went public with their intentions to merge in May 2023, with more than 99% of partners going on to vote in favour of the move.

A&O Shearman ( believes is has a depth of experience and diversity of talent to operate at the forefront of business across every industry sector, market, and geography, and claims to be the only firm equally fluent in US law, English law, and the laws of the world’s most dynamic markets.

Adam Hakki, co-chair of the global A&O Shearman board and executive committee and chair of the firm’s US business, said: “The combination of two of the world’s most prestigious law firms, with complementary strengths and shared values, has been carefully designed to deliver – at the highest level – what the firms’ respective clients and colleagues have told us they are seeking and will find nowhere else.”

The combined entity already advises more than a third of New York Stock Exchange-listed businesses and a fifth of the NASDAQ, as well as many more of the world’s leading organisations listed on the London Stock Exchange, Euronext, Euronext Paris, Frankfurt Stock Exchange, Abu Dhabi Securities Exchange, Dubai Financial Market and the Tokyo and Hong Kong Stock Exchanges.

Allen & Overy’s Belfast office opened in 2011and is the second largest office in the A&O network by headcount, employing 700-plus people.

It includes a support services centre which delivers business services such as document & design, finance, human resources, IT, library & information and marketing & business development – to the firm’s global network.

Allen & Overy now employ around 600 people from its Belfast base, which opened in 2011.
Allen & Overy's Belfast base at 68 Donegall Quay opened in 2011

Through the Advanced Delivery Legal function, A&O Belfast has been at the forefront of delivering legal services to clients in new and flexible ways, with proportionate lower-cost, tech enabled resourcing and end-to-end managed legal services.

A&O Shearman’s headquarters is currently located at One Bishops’ Square in London (formerly A&O’s office), with plans to relocate to Broadgate near Liverpool Street station by 2027.

Legal Cheek, the most-read legal website in the UK, reported in April that newly qualified associates at the firm will start on a salary of £125,000, with trainees receiving £50,000 in year one, increasing to £55,000 in year two.