Allen & Overy
A former London-headquartered international law firm that merged with Shearman & Sterling to create A&O Shearman.
Last updated September 23, 2026
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Overview
Allen & Overy was a British multinational law firm headquartered in London and one of the firms commonly associated with the United Kingdom’s Magic Circle of leading international practices. Founded on 1 January 1930 by George Allen and Thomas Overy, it began as a commercial law practice and developed into a broad corporate and financial-services firm. Its principal work included banking and finance, capital markets, corporate transactions, mergers and acquisitions, projects and infrastructure, disputes, arbitration, and regulatory matters. The firm’s early reputation was strengthened by George Allen’s role as adviser to King Edward VIII during the 1936 abdication crisis. By the outbreak of the Second World War, Allen & Overy had become an established City of London practice. It later expanded beyond traditional commercial work through significant financial-market mandates, including advice on the first Eurobond, issued in the 1960s for the Italian motorway company Autostrada. That transaction helped move the firm toward the international banking and capital-markets practice for which it became particularly known. From the 1970s onward, Allen & Overy expanded its corporate and finance capabilities in the United Kingdom and overseas. International work became increasingly important: non-UK clients generated more revenue than UK clients by 1996, and accounted for approximately two-thirds of revenue in 1998. The firm built a network spanning major financial and commercial centres. Its international development included the recruitment of a banking and finance team in Paris in 1999, the combination with parts of the Amsterdam, Brussels and Luxembourg offices of Loeff Claeys Verbeke in 2000, and the opening of a Johannesburg office in 2014, described as the first sub-Saharan African office established by a Magic Circle firm. Allen & Overy converted its worldwide partnership into a limited liability partnership in 2004, operating with associated undertakings in some jurisdictions. Before its combination with Shearman & Sterling, it had more than 40 offices in 31 countries, approximately 590 partners, and more than 5,800 employees according to the cited reference material. Its clients included companies, banks, investment firms, governments, public bodies, and other institutions requiring cross-border legal advice. The firm also experienced restructuring and public scrutiny. In the aftermath of the 2008 financial crisis, it completed a global redundancy programme in 2009 affecting partners, fee-earners, and support staff, and it separated its private-client department into Maurice Turnor Gardner LLP. The firm introduced a part-time option for full-equity partners in 2010, launched its A&Out LGBT+ network in 2016, and provided pro bono advice to Stonewall on the United Kingdom’s so-called Alan Turing law. It faced criticism concerning diversity and gender pay differences, while a 2021 assessment identified it as particularly active in transactional work for fossil-fuel companies. On 21 May 2023, Allen & Overy and Shearman & Sterling announced agreed merger terms. Partners approved the combination in October 2023 by more than 99 percent, and the transaction was completed in 2024, creating A&O Shearman. Allen & Overy consequently ceased operating as a standalone firm under its former organizational identity. Historical references to the brand therefore describe the pre-merger firm, while its successor organization is A&O Shearman.
History
Allen & Overy was founded in London on 1 January 1930 by George Allen and Thomas Overy, who had previously been partners at Roney & Co. The founders intended to build a commercial practice. George Allen’s work advising King Edward VIII during the 1936 abdication crisis helped raise the firm’s profile, and by the beginning of the Second World War it was established among the leading City of London firms. The firm’s later development was closely connected with the growth of international finance. It advised on what is described in the reference material as the first hostile takeover in the City of London and acted for S. G. Warburg & Co. In the 1960s it arranged the first Eurobond, issued by the Italian motorway group Autostrada. The Eurobond mandate broadened the practice from a primarily commercial firm into one with a substantial financial and capital-markets capability. During the 1970s, its corporate and finance practices expanded both domestically and internationally. International clients became central to the business. In 1996, they generated more revenue than UK clients, and by 1998 they represented about two-thirds of revenue. In 1999, Allen & Overy recruited a Paris banking and finance team from its then ally Gide Loyrette Nouel. In 2000, it combined with parts of the Amsterdam, Brussels, and Luxembourg offices of Loeff Claeys Verbeke, strengthening its continental European network. In May 2004, the worldwide partnership converted to Allen & Overy LLP. The LLP worked with associated undertakings in certain jurisdictions to deliver a worldwide legal practice. The firm passed £1 billion in turnover in July 2008, and that year more than half of turnover was generated outside London. The global financial crisis then led to a restructuring programme completed in 2009. The programme eliminated 47 partner positions and approximately 200 fee-earner and 200 support-staff roles worldwide, with about half of the support-staff reductions based in London. A further 35 partners were de-equitised. The same year, the private-client practice was separated and became Maurice Turnor Gardner LLP. Allen & Overy continued to expand its international footprint and in 2014 opened an office in Johannesburg. This was described as the first office in sub-Saharan Africa established by a Magic Circle firm. Before its merger, the firm had more than 40 offices in 31 countries across Africa, Asia-Pacific, Europe, Latin America, the Middle East, and North America. Workplace and social-policy issues also formed part of its history. In 2010, Allen & Overy introduced an option for full-equity partners to work part-time, a policy regarded as significant within the large-law-firm sector. Its A&Out LGBT+ network was launched in 2016. The network supported awareness and networking activities, and the firm advised Stonewall on a pro bono basis regarding the 2017 Policing and Crime Act, commonly called the Alan Turing law. In 2018, the firm faced criticism concerning diversity and gender pay differences. A 2021 assessment also identified it as one of the firms conducting substantial transactional work for fossil-fuel companies. On 21 May 2023, Allen & Overy and Shearman & Sterling announced that they had agreed terms for a merger. The proposed combination was intended to create a global firm with more than 4,000 attorneys across 48 offices and combined revenue stated in the reference material at approximately $3.4 billion. More than 99 percent of partners at both firms approved the transaction on 13 October 2023. Completion followed in 2024, when the combined organization adopted the name A&O Shearman. Allen & Overy therefore no longer operates as a separate law firm.
- 2024
A&O Shearman begins operations
[2]The merger with Shearman & Sterling completed and the combined firm adopted the A&O Shearman name.
- 2023
Merger terms agreed with Shearman & Sterling
[2]Allen & Overy and Shearman & Sterling announced agreed terms for a cross-border merger.
- 2023
Partners approve merger
[1]More than 99 percent of partners at both firms approved the proposed transaction on 13 October.
- 2016
A&Out LGBT+ network launched
[1]The firm established an internal LGBT+ network supporting awareness, events, and networking.
- 2014
Johannesburg office opens
[1]The firm opened a Johannesburg office, described as the first sub-Saharan African office of a Magic Circle firm.
- 2009
Post-crisis restructuring
[1]Allen & Overy completed a global redundancy programme and separated its private-client practice into Maurice Turnor Gardner LLP.
- 2008
Turnover exceeds one billion pounds
[1]The firm passed £1 billion in turnover and generated more than half of its turnover outside London.
- 2004
Worldwide partnership converts to LLP
[1]The worldwide partnership became Allen & Overy LLP and continued working with associated undertakings in some jurisdictions.
- 2000
Combination with Loeff Claeys Verbeke offices
[1]The firm merged with parts of the Amsterdam, Brussels, and Luxembourg offices of Loeff Claeys Verbeke.
- 1999
Paris banking team recruited
[1]Allen & Overy hired a banking and finance team in Paris from Gide Loyrette Nouel.
Products and positioning
An international commercial law firm serving major companies, financial institutions, governments, and institutional clients, with particular strength in cross-border finance, capital markets, and complex corporate transactions.
Legal services
Banking and Finance
A core historical practice advising banks, financial institutions, companies, governments, and public-sector bodies on lending, structured finance, project finance, asset finance, and other domestic and cross-border financing arrangements. The practice was central to the firm’s reputation in international financial law and reflected its development from a general commercial practice into a major finance-focused international firm.
Legal services
Capital Markets
Advice on debt and equity offerings, securities transactions, Eurobonds, and related capital-markets matters. The work served issuers, underwriters, investors, banks, and other financial intermediaries, with particular emphasis on complex international offerings and the legal requirements of multiple jurisdictions.
Legal services
Corporate and M&A
Legal advice on mergers, acquisitions, disposals, hostile takeovers, joint ventures, restructurings, governance, and other corporate transactions. The practice served multinational companies, financial sponsors, investors, and financial institutions, often involving several legal systems and regulatory regimes.
Legal services
Projects and Infrastructure
Advice relating to major infrastructure and development projects, including their financing, construction, ownership, operation, and regulatory framework. This offering connected the firm’s corporate, finance, and public-law capabilities for institutional and public-sector clients.
Legal services
Dispute Resolution and Arbitration
Representation and advice in commercial disputes, international arbitration, and related contentious matters. The practice supported companies, financial institutions, and public bodies in cross-border proceedings and complex contractual or regulatory disputes.
Legal services
Regulatory and Compliance
Advice on financial regulation, corporate compliance, investigations, and other regulatory obligations affecting internationally active businesses and financial institutions. The work complemented the firm’s transactional practices by addressing the legal and supervisory requirements surrounding cross-border commerce and finance.
Controversies
Marketing campaigns
- 2017Pro bono advice on the Alan Turing law
United Kingdom
Allen & Overy advised Stonewall on a pro bono basis concerning the United Kingdom legislation commonly known as the Alan Turing law, which provided an amnesty mechanism for certain historical convictions and cautions relating to homosexual acts.
Outcome. The work supported Stonewall’s legal and policy activity surrounding the Policing and Crime Act 2017.
- 2016A&Out LGBT+ network
United Kingdom · International firm network
Allen & Overy launched A&Out to support LGBT+ colleagues, raise awareness of LGBT+ issues, and provide events and networking opportunities. The initiative formed part of the firm’s workplace inclusion activity.
Outcome. The network remained a visible part of the firm’s diversity and inclusion activity; the firm was later placed in the top 100 of the 2018 Stonewall Workplace Equality Index.
Brand decisions
2023
Merger with Shearman & SterlingM&ABackground
Both firms sought to combine their international networks and broaden their capacity to serve clients across major financial and commercial markets.
Action taken
Allen & Overy agreed merger terms with Shearman & Sterling; partners at both firms subsequently approved the transaction by more than 99 percent.
Aftermath
The transaction completed in 2024 and created A&O Shearman, ending Allen & Overy’s operation as an independent firm.
Combined revenue. $3.4 billion (Projected or stated at the time of the 2023 merger announcement; currency and basis are as reported in the reference material)
2010
Part-time option for full-equity partnersStrategyBackground
The firm sought to address work-pattern flexibility and inclusion within a large international partnership.
Action taken
Allen & Overy announced that full-equity partners could elect to work part-time.
Aftermath
The policy was described as a significant development for the legal sector and was presented as an early initiative of its kind among major international firms.
2009
Post-financial-crisis restructuringStrategyBackground
The global financial crisis placed pressure on law-firm demand and operating costs, prompting Allen & Overy to review its worldwide staffing and partnership structure.
Action taken
The firm completed a redundancy programme affecting partners, fee-earners, and support staff, and de-equitised additional partners.
Aftermath
The restructuring reduced the firm’s global workforce, while its private-client department was separated into Maurice Turnor Gardner LLP.
Recent events
- 2024
Allen & Overy and Shearman & Sterling complete merger[2]
M&A · Leadership change
The firms completed their combination and began operating as A&O Shearman, ending Allen & Overy’s existence as a standalone firm.
- 2023
Allen & Overy announces merger agreement with Shearman & Sterling[2]
M&A
The two international law firms announced terms for a combination intended to create a global firm with more than 4,000 lawyers across 48 offices.
- 2023
Partners approve Allen & Overy and Shearman & Sterling combination[1]
M&A
More than 99 percent of partners at both firms approved the proposed merger in October 2023.
- 2021
Assessment identifies Allen & Overy among firms active in fossil-fuel transactions[1]
Other
A published assessment singled out Allen & Overy for undertaking substantial transactional work for fossil-fuel companies.
- 2018
Allen & Overy faces criticism over diversity and gender pay gap[1]
Other
The firm was among legal-sector employers criticized in public discussion concerning workplace diversity and gender pay disparities.
Sources2 sources
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