who is bill ackman

Bill Ackman is an American billionaire hedge fund manager, founder, and CEO of Pershing Square Capital Management. He is known as an activist investor, which means he acquires significant stakes in companies to advocate for management or strategic changes. As of 2025, his net worth is estimated at around $9.4 billion. Ackman is also a philanthropist who has pledged to give away at least half of his wealth to charitable causes. He has been involved in high-profile investments and public activism, including political donations and various philanthropic initiatives. Ackman studied at Harvard College and Harvard Business School and has a notable presence in both finance and philanthropy.