Clare O’Brien regularly advises major US and international clients on their public and private mergers and acquisition transactions, including public company restructurings, joint ventures and large public transactions.  She also provides counsel on corporate law questions, including corporate governance matters.

Ms. O’Brien has been consistently acknowledged as a leading M&A lawyer and has received numerous accolades including “Dealmaker of the Year”  by The American Lawyer, Top U.S.A. Women Dealmaker by the Global M&A Network 2021 as well as being named one of The Deal’s Top Women in Dealmaking 2021, 2022 and 2023 Lists for her work in Mergers & Acquisitions.

Prior to joining Shearman & Sterling, Ms. O’Brien worked with the law firm of Brady & Tarpey, P.C., where her practice included cross-border corporate transactions, litigation and domestic relations.  She began her legal career at the Irish law firm of Eugene F. Collins & Son.

• Mubadala Capital, established as the financial investment arm of Mubadala Development Company, in connection with the establishment of several private lending programs with global financial institution origination partners, which provide financing solutions to U.S. and European middle-market businesses and its pending acquisition, together with members of Fortress management, of all of the indirect interests in Fortress Investment Group LLC
• Mubadala Investment Company, a public joint stock company wholly owned by the Government of the Emirate of Abu Dhabi, in various transactions, including its global business partnership with General Electric Company, its investment in the EBX Group (and related restructuring transactions) and its investment with Trafigura Pte. Ltd. in MMX Porte Sudeste
• Raytheon Company in various transactions, including its 2020 “merger of equals” combination with United Technologies Corporation
• Ardagh Group in various transactions, including its recently completed exchange offer to exchange its Class A common shares for shares of Ardagh Metal Packaging S.A., its subsidiary, its US$8.3 billion “de-SPAC” transaction involving the combination of its metal packaging business with Gores Holdings V, Inc., a special purpose acquisition company, the combination of its Food & Specialty Metal Packaging business with the packaging business of Element Holdings II L.P., an entity controlled by The Ontario Teachers' Pension Plan, to form Trivium Packaging, its acquisition of certain metal beverage can manufacturing assets from Ball Corporation and Rexam PLC with an enterprise value of $3.42 billion, and its sale of Anchor Glass Container Corporation to an affiliate of KPS Capital Partners LP.
• Boston Scientific Corporation in various transactions, including its recently announced pending acquisition of Axonics Inc., a publicly traded MedTech company, for approximately $3.7 billion, its 2022 acquisition of Apollo Endosurgery, Inc., a Delaware public company, its acquisition of Baylis Medical Company, a privately held Canadian company, its acquisition of BTG plc, a public company organized under the laws of England and Wales, its acquisition of the advanced biologic tissue capabilities of Neovasc Inc. and 15% of Neovasc's common shares, its acquisition of the men's health and prostate health businesses of Endo International plc, the sale of its neurovascular business to Stryker Corporation, its acquisition of and the restructuring of its interests in Advanced Bionics Corporation, its acquisition of Guidant Corporation, the sale of Guidant's vascular businesses to Abbott Laboratories and in various corporate and other transactional matters
• Corning Incorporated in various corporate and transactional matters, including its acquisitions of the fiber and copper connectivity solutions business of 3M Company, Axygen BioScience, Inc. and the Discovery Labware business of Becton, Dickinson and Company
• Bunge Limited in various transactions, including its acquisition of a majority ownership interest in Loders Croklaan Group B.V., the sale of its Brazilian fertilizer business to Yara International ASA, its sale of Brazilian Fertilizer Nutrients Assets to Vale S.A., its acquisition of Usina Moema Participações S.A. and its terminated merger agreement with Corn Products International, Inc.
• Danone in various transactions, including its acquisitions of The YoCrunch Company, YoCream International, Inc., and Medical Nutrition USA, Inc. and transactions with an affiliate of Kelso & Company, Suntory Water Group, The Coca-Cola Company, and Stonyfield Farm, Inc.
• SunGard Data Systems, Inc. in its acquisition by seven private equity funds led by Silver Lake Partners, the sale of its Higher Education businesses in 2012 to affiliates of Hellman & Friedman LLC, and its split-off of SunGard Availability Services Inc.
• P.H. Glatfelter Company in various matters, including its pending acquisition of Jacob Holm, its acquisitions (in two separate transactions) of facilities in Germany and the U.S. from Georgia Pacific, the sale of its Specialty Papers division to an affiliate of Lindsay Goldberg, its acquisition of certain manufacturing assets in Germany, Italy and France from subsidiaries of Georgia-Pacific LLC, and its acquisition of Concert Industries Corp. from Brookfield Special Situations Management Limited
• Quest Diagnostics Incorporated in various corporate and transactional matters, including its acquisition of Spectrum Laboratories Holdings, Inc., a portfolio company of Welsh, Carson, Anderson & Stowe, its 2011 acquisitions of Athena Diagnostics, Inc. and Celera Corporation and its acquisitions of AmeriPath Corporation, Unilab Corporation and the clinical laboratory business of SmithKline Beecham Corporation
• The Special Committee of HCA Inc. in connection with the acquisition of HCA by three private equity funds