Sebastian Alsheimer

Sebastian Alsheimer is a New York partner at Cleary Gottlieb Steen & Hamilton LLP, who focuses on shareholder engagement and activism defense. He advises public companies facing activist investors, proxy contests, and governance disputes. His work helps boards and management teams understand risks, prepare responses, and protect company value. He has advised on more than 400 activism matters worldwide. His practice also includes M&A, capital markets, business law, corporate advisory work, and corporate governance matters involving complex business decisions and shareholder pressure.

Sebastian earned an A.B. from Harvard College. He earned an M.A. from the University of Oxford. He earned an LL.M. from Columbia Law School. He also earned an M.B.A. from Yale School of Management. This education supports his work across law, business, finance, and board-level strategy. It also gives him a practical view of corporate decisions, investor concerns, and governance duties that arise during high-stakes shareholder situations.

Sebastian has built a legal career focused on both strategy and defense. He joined his current role as a partner in January 2026 after working at another major international law firm. Earlier, he represented activist investors, which gave him insight into how dissident shareholders plan campaigns and pursue change. That background helps him advise companies with a clear understanding of investor goals, tactics, and pressure points during negotiations or public contests.

Sebastian Alsheimer helps clients by guiding them through difficult investor challenges with steady legal and strategic advice. He counsels companies during proxy contests, withhold campaigns, consent solicitations, 13D filings, settlement talks, hostile takeover matters, and contentious M&A issues. His work supports boards as they respond to demands, evaluate options, and communicate with shareholders. Through this practice, he helps companies manage disputes, reduce risk, and make informed decisions under pressure.

Law Office Affiliations

• Partner, Cleary Gottlieb Steen & Hamilton LLP
• Member, New York State Bar Association

Licensed State

• New York

Education

• Columbia Law School
  Master of Laws (LLM)
• Yale School of Management
  Master of Business Administration (MBA)
• University of Oxford
  Master of Arts (MA)
• Harvard College
  Bachelor of Arts (BA)

Awards & Badges