Bill Ackman Bio
William Albert Ackman, known publicly as Bill Ackman, is an American billionaire hedge fund manager and activist investor. He is the founder and chief executive officer of Pershing Square Capital Management, an investment firm he launched in 2004 that has become known for concentrated public-company positions and high-profile activist campaigns.
Over the course of his career, Ackman has built a reputation for taking bold, often controversial positions in companies such as MBIA, Canadian Pacific Railway, Valeant Pharmaceuticals, Chipotle Mexican Grill, and Herbalife. Forbes estimated his net worth at approximately $9 billion as of July 2025, reflecting both the returns generated by his fund and the prominence he has earned on Wall Street and in the wider public sphere.
Early Life and Background
Bill Ackman was born on May 11, 1966, in Chappaqua, New York. He is the son of Lawrence David Ackman, the former chairman of the New York real estate financing firm Ackman-Ziff Real Estate Group, and Ronnie I. Ackman, née Posner. He is of Ashkenazi Jewish descent and grew up in the suburban New York community where he was raised alongside his siblings.
Ackman attended Horace Greeley High School in Chappaqua, where he played on the school’s tennis team and also competed as a junior tennis player, though not at a highly competitive level. He graduated from the high school in 1985 and went on to enroll at Harvard College, where he earned a Bachelor of Arts degree magna cum laude in social studies in 1988. His undergraduate thesis, titled “Scaling the Ivy Wall: The Jewish and Asian American Experience in Harvard Admissions,” reflected an early interest in policy and public debate.
After completing his undergraduate studies, Ackman continued at Harvard and earned a Master of Business Administration degree from Harvard Business School in 1992. His time at Harvard connected him with future business partners and shaped the analytical framework that would later define his investment approach.
Path to Pershing Square Capital Management
Shortly after business school, Ackman co-founded the investment firm Gotham Partners in 1992 with fellow Harvard graduate David P. Berkowitz. The firm initially made small investments in public companies and gradually grew its profile. By 1995, Ackman and Gotham had attracted notice after partnering with the insurance and real estate firm Leucadia National to bid for Rockefeller Center, an effort that did not succeed but helped Gotham raise additional capital. By 1998, Gotham had grown to roughly $500 million in assets under management, and by 2002 it had become mired in litigation with various external shareholders.
While at Gotham, Ackman began the research efforts that would later make him a household name on Wall Street. In 2002, he initiated a deep investigation of MBIA, the bond insurer, in order to challenge Standard & Poor’s AAA rating of its bonds. He spent more than $100,000 on legal fees to copy hundreds of thousands of pages of documents, and he ultimately built a profitable short position against MBIA that he covered in January 2009. The MBIA campaign established Ackman as a fearsome activist investor willing to take on large, entrenched institutions.
When Gotham Partners wound down, Ackman launched Pershing Square Capital Management in 2004 with $54 million drawn from his personal funds and from his former business partner Leucadia National. From the outset, Pershing Square pursued a concentrated, activist style, and Ackman has since described his first rule of activist investing as making a bold call that nobody believes in.
Bill Ackman Career
Early Career (1992–2003)
Ackman’s early career was defined by the launch and growth of Gotham Partners, where he developed a taste for activist investing in small public companies. The firm gave him a platform to test shareholder engagement strategies, and its 1995 bid for Rockefeller Center with Leucadia National helped establish his reputation in real estate finance circles.
By the early 2000s, Ackman had turned his attention to the bond insurance industry, beginning his long-running critique of MBIA. The legal battle and public campaign against MBIA’s structured finance business laid the groundwork for Pershing Square’s later approach of pairing rigorous research with aggressive public advocacy. During this period he also developed a public rivalry with fellow investor Carl Icahn, a feud that culminated in a 2011 ruling requiring Icahn to pay Ackman millions in profits, interest, and legal fees.
Pershing Square Breakthrough (2004–2014)
Pershing Square Capital Management was launched in 2004 with $54 million in initial capital, and Ackman quickly put the firm to work on activist campaigns targeting large public companies. In 2010, the fund began acquiring shares of J. C. Penney, eventually building an 18 percent position, although Ackman departed the board in 2013 following a disagreement with fellow directors.
In 2011, Pershing Square began acquiring shares of Canadian Pacific Railway, eventually becoming the railway’s largest shareholder. Ackman initiated a proxy contest in November 2011, and at the railway’s annual meeting in May 2012, close to 90 percent of shareholder votes supported his dissident slate, leading to the replacement of the chief executive and multiple board members. The Globe and Mail’s Report on Business Magazine subsequently named Ackman “CEO of the Year.”
By January 2015, LCH Investments had named Ackman one of the world’s top 20 hedge fund managers after Pershing Square delivered $4.5 billion in net gains for investors in 2014, bringing the fund’s lifetime gains to $11.6 billion since its 2004 launch. During the same period, Ackman began his billion-dollar short bet against Herbalife, a campaign that would dominate headlines for years and trigger one of the most closely watched rivalries in modern finance.
Recent Era (2015–Present)
After a stretch of weak performance between 2015 and 2018, Ackman reworked Pershing Square’s management and the firm returned 58.1 percent in 2019, a result Reuters characterized as one of the world’s best-performing hedge funds for that year. Ackman continued to deploy capital in high-conviction positions, taking a stake in Chipotle Mexican Grill starting in 2016 and helping to recruit Brian Niccol as chief executive in 2018.
In April 2016, Ackman testified before the United States Senate Special Committee on Aging alongside executives from Valeant Pharmaceuticals, a company in which Pershing Square had been a major investor. Ackman exited the Valeant position in March 2017 at a substantial loss. In 2021, Pershing Square acquired a 10 percent stake in Universal Music Group, one of the fund’s largest positions, and Ackman joined the company’s board in 2022, a position he held until 2025.
More recently, Ackman chaired Howard Hughes Holdings from 2010 until 2024, when he stepped down, and he rejoined the board as Executive Chairman in May 2025 after Pershing Square increased its investment in the company to 47 percent. In 2024, he attempted to take a new fund, Pershing Square USA, public, but withdrew the initial public offering on August 1, 2024, after securing only $2 billion. The firm continues to manage a concentrated portfolio of public-company positions.
Notable Events and Milestones
One of Ackman’s most dramatic interventions came in March 2020, when he hedged Pershing Square’s portfolio by investing $27 million in credit protection, a move that generated roughly $2.6 billion in less than a month during the early stages of the COVID-19 market crash. Days later, he appeared on CNBC and called for a 30-day shutdown of the American economy, a televised moment that drew both praise and criticism when he subsequently acquired discounted equity stakes in the very sectors he had warned could fail. In 2025, Ackman received a wild card berth at the Hall of Fame Open professional tennis tournament at the age of 59, a decision that drew sharp criticism from professional players and tennis journalists and led him to offer a $10 million endowment to the International Tennis Hall of Fame, which the organization declined.
Bill Ackman Career Wins
Bill Ackman’s career has been defined by a series of high-profile activist campaigns and concentrated investment positions. While his most public disputes have often centered on companies whose stock he has bet against, his career has also produced substantial gains for Pershing Square investors and a string of board-level victories at large public companies.
Career Highlights
Among Ackman’s most celebrated wins was the 2012 proxy contest at Canadian Pacific Railway, where roughly 90 percent of shareholders backed his dissident slate, and the subsequent honor of being named “CEO of the Year” by The Globe and Mail’s Report on Business Magazine. Pershing Square also delivered $4.5 billion in net gains in 2014 alone, helping Ackman earn recognition from LCH Investments as one of the world’s top 20 hedge fund managers. The fund’s 2019 return of 58.1 percent was hailed as one of the best in the global hedge fund industry.
More recently, Ackman’s timely purchase of credit protection in early 2020 generated $2.6 billion in less than a month, and his 2016 investment in Chipotle Mexican Grill, one of Pershing Square’s top holdings from 2017 to 2024, was credited with helping the chain recover from years of losses. After selling the bulk of his Universal Music Group shares in 2024, Ackman retained a board seat until 2025 and oversaw one of the most successful private placements in the fund’s history.
Other Wins and Achievements
Ackman’s Herbalife campaign, while ultimately ending in a financial loss when he exited the short in February 2018, triggered multiple investigations by federal and state authorities, including a 2016 settlement under which Herbalife paid $200 million and restructured its business. He has also been recognized through listings on The Chronicle of Philanthropy’s Philanthropy 50 in 2011 and 2021, reflecting his extensive charitable giving through the Pershing Square Foundation.
Bill Ackman Family
Family Background
Bill Ackman was born into a family with deep roots in New York real estate finance. His father, Lawrence David Ackman, served as chairman of Ackman-Ziff Real Estate Group, and his mother is Ronnie I. Ackman, née Posner. He is of Ashkenazi Jewish descent, a background that has shaped elements of his philanthropic and political engagement in later years.
Personal Life
Ackman married landscape architect Karen Ann Herskovitz on July 10, 1994, and the couple had three children before separating in December 2016. In 2018, he became engaged to Israeli-American designer Neri Oxman, and the two married at the Central Synagogue in Manhattan in January 2019. They had their first child together in spring 2019. Ackman has also been a prominent donor and public commentator, lending his voice to debates on philanthropy, higher education, and political issues, including support for Israel following the October 7 attacks and an endorsement of Donald Trump in the 2024 United States presidential election.