Kai co-chairs Sidley’s Shareholder Activism & Corporate Defense Practice.  He has 25 years of experience in corporate law and spends 100% of his time on activism campaigns, proxy fights, short attacks and hostile takeovers.  Kai has been called “a pioneer in the field of shareholder activism defense” (Chambers USA) and one “of the best lawyers in America” (The Legal 500).

In the past five years, Kai has defended over 500 activist campaigns and 150 proxy contests globally as well as approximately 25% of all U.S. late-stage proxy fights, more than any other defense attorney in the world.  Under Kai’s leadership, Sidley rose to the No. 1 in all activism and corporate defense league tables since 2020, including No. 1 rankings by Bloomberg, FactSet, Diligent, and LSEG.

The American Lawyer named Kai “Dealmaker of the Year” for his proxy contest work in 2019. Forbes recognized him in its 2025 “America’s Top Lawyers” list.  Crain's New York Business named Kai one of "2025 Notable M&A Dealmakers."  Since 2017, Chambers USA has recognized Kai as top-ranked lawyer, listing him in Band 1 for “Corporate/M&A: Takeover Defense” in New York. Since 2023, Kai has also been named one of the leading lawyers for “Shareholder Activism – Advice to Boards” by The Legal 500. He was elected for the NACD Directorship 100 as a “Governance Professional” each year since 2022. Kai was also named in the Lawdragon 500 “Leading Dealmakers in America” every year since 2021. Kai was elected to the American College of Governance Counsel, the honorary association of governance lawyers, in 2020.

Kai serves on the board of the New York Chapter of the NACD and served on the Law360 Mergers & Acquisitions Editorial Board for several years. He speaks regularly on panels and at universities around the world (including Harvard and Frankfurt). He is frequently interviewed and quoted as a thought leader by the media, including The New York Times, The Wall Street Journal, CNBC, The Economist, TIME, Bloomberg, Reuters, Financial Times, CNN, USA Today, Forbes, Law360, and The Deal.

Kai holds a Ph.D., magna cum laude, from Freiburg University; an Executive MBA, summa cum laude (best of class), from Muenster Business School; and an LL.M., James Kent Scholar, from Columbia Law School. He was in the top 0.1% nationwide in his First Legal State Exam (J.D. equivalent) and in the top 1.5% nationwide in his Second Legal State Exam in Germany.