Cooley has announced the addition of Sean W. Brownridge as a partner in its M&A group and as chair of its activism defense practice. Brownridge will be based in Cooley’s New York office, bringing experience advising boards, management teams, and investors on activist engagements, including high-profile proxy contests and campaigns. He is recognized by The Legal 500 as a “Next Generation Partner” for Shareholder Activism.
“Sean is a force in his field, and we are honored to have him join our market-leading team,” said Cooley CEO and partner Rachel Proffitt. “Sean’s experience will be invaluable as we redefine what it means to be a destination defense practice servicing the complex needs of public companies across an elite, multidisciplinary platform. With teammates like Sean, we continue our commitment to scale with the fastest-growing and most scrutinized companies in the world.”
Brownridge previously worked at McDermott Will & Schulte where he advised leading engaged investors on shareholder activism matters such as investment opportunities, alternative strategies, settlements, proxy contests, and contested M&A transactions. Before that role, he was part of Kirkland & Ellis’ shareholder activism & hostile takeover defense group and clerked for Judge Karen L. Valihura of the Delaware Supreme Court.
“Sean’s arrival will be a key differentiator to our clients, particularly as our technology and life sciences companies increasingly sit in the crosshairs as potential activist targets,” said Jamie Leigh, Cooley partner and chair of the firm’s global M&A practice group. “Sean’s historical experience advising leading activists as well as management groups and boards adds another elite layer to our activism defense team.”
“I’m grateful to be joining Cooley, which I’ve long admired for its position within the corporate landscape and depth of public company expertise,” said Brownridge. “Addressing shareholder activism effectively is a fundamental and ever-evolving function of boards and management teams, and I look forward to partnering with Cooley’s many talented lawyers to build a standout defense practice that enables our clients to productively navigate their most critical shareholder engagements.”
Cooley has been ranked among top shareholder activism practices by The Legal 500. Since 2020, the firm has advised on over 1,600 M&A transactions valued at more than $735 billion overall. Bloomberg named Cooley #1 globally for tech and life sciences M&A deal count for the first half of 2025.
The firm employs nearly 1,400 lawyers across 19 offices located in the United States, Asia, and Europe with a total workforce exceeding 3,000 people.