Clare O'Brien


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 a “Dealmaker of the Year” award by The American Lawyer.

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.

Selected Experience

  • Ardagh Group in 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 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 
  • HeartWare International, Inc. in its sale to Medtronic, Inc., and its terminated acquisition transaction with Thoratec Corporation
  • Heidelberg Cement AG, in its sale of a cement plant and eight terminals to a subsidiary of the Colombian cement and concrete producer Cementos Argos S.A., and its sale of its building products business in North America (excluding Western Canada) and the United Kingdom to an affiliate of Lone Star Funds
  • Mubadala Development Company, a public joint stock company wholly owned by the Government of the Emirate of Abu Dhabi, in connection with various matters, 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


  • Incorporated Law Society of Ireland (Irish Roll of Solicitors), 1985
  • Trinity College, Dublin, B.A. Legal Science, 1982


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