DEREK ZABA co-chairs Sidley’s Shareholder Activism & Corporate Defense practice. He spends 100% of his time on shareholder activism, contested and complex M&A, and corporate governance matters. With more than two decades of experience, Derek has been involved in hundreds of activist campaigns and contested M&A situations. Prior to Sidley, Derek was the head of the activism and corporate defense practice at a leading shareholder engagement and corporate governance advisory firm. He also served as a partner and investment professional at activist and event-driven hedge funds. Derek is a highly sought after speaker on the topics of investor activism, contested M&A, and ESG/corporate governance at panels and universities and teaches a class on shareholder activism, contested M&A, and corporate governance at Stanford University Law School.
During Derek’s tenure, Sidley has risen to the top of all shareholder activism defense league tables, including its No. 1 rankings by Bloomberg, FactSet, LSEG (formerly Refinitiv/Thomson Reuters), and Diligent for North America. Sidley has been ranked in Band 1 for “Takeover Defense” by Chambers USA in 2022, The Legal 500 in the U.S. for “Shareholder Activism – Advice to Boards” in 2023, and was recognized by The Deal as “Activist Defense Law Firm of the Year (Large Cap)” in 2021 and 2022.
Since 2023, Derek has been named one of the leading lawyers for “Shareholder Activism – Advice to Boards” by The Legal 500, calling him and his partner Kai Liekefett “two of the best lawyers in America.” In 2022, The American Lawyer named Derek as a Trailblazer in the Western Region of the United States for his work in shareholder activism and contested M&A. Derek was also recognized in the 2021–2025 editions of Chambers USA as one of the leading lawyers in New York Corporate/M&A: Takeover Defense with clients noting that “he is deeply knowledgeable, very easy to work with and is able to bring defense expertise with multiple perspectives,” and, “his client advice is consistently excellent and nuanced, and he delivers it with a calmness that is often important in tense activist situations.” Derek was selected as one of the Lawdragon 500 “Leading Dealmakers in America” in 2025.
He holds a J.D. from Stanford Law School, where he graduated Order of the Coif; an MBA from the Olin School of Business at Washington University in St. Louis, concentrating in Finance; and a bachelor’s degree in Systems Science and Mathematics, cum laude, from the School of Engineering and Applied Science at Washington University in St. Louis. While at Washington University, he led university teams that won the highest award at the Consortium for Mathematics and Its Applications (COMAP) international Mathematical Contest in Modelling in consecutive years.
Derek is a member of the State Bars of California and New York.