Bill Ackman

Bill Ackman
Born	William Albert Ackman 11 5, 1966
Birthplace	Chappaqua, New York, U.S.
Nationality	American
Occupation	Hedge fund manager
Title	Founder and CEO, Pershing Square Capital Management
Known for	Activist investing, Pershing Square Capital Management
Education	Harvard University (BA, MBA)
Spouse(s)	Karen Ann Herskovitz (m. 1994; div.) Neri Oxman (m. 2019)
Website	[https://www.pershingsquareholdings.com/ Official site]

William Albert Ackman (born May 11, 1966), known as Bill Ackman, is an American billionaire hedge fund manager, activist investor, and philanthropist. He is the founder and chief executive officer of Pershing Square Capital Management, a New York City-based investment management company. Ackman has built a career around large, concentrated bets on publicly traded companies, frequently taking activist positions to push for changes in corporate governance, strategy, and management. His high-profile campaigns—both successful and unsuccessful—have made him one of the most closely watched figures on Wall Street. Ackman's investment record includes prominent wins in companies such as Canadian Pacific Railway and notable losses in positions including Valeant Pharmaceuticals and J.C. Penney. A long-time donor to Democratic candidates and organizations, Ackman shifted his political alignment in 2024 when he endorsed Donald Trump in the 2024 United States presidential election. In recent years, Ackman has become an increasingly vocal public commentator on politics, higher education, and geopolitics, particularly following the October 7, 2023, attacks on Israel. As of early 2026, Pershing Square's portfolio has included significant positions in technology companies, with Ackman making headlines for a large new stake in Meta Platforms.

Early Life

William Albert Ackman was born on May 11, 1966, in Chappaqua, New York, an affluent hamlet in Westchester County. He grew up in a Jewish family with roots in the New York business community. His father, Lawrence D. Ackman, was a real estate financier who served as chairman of a New York mortgage company. The elder Ackman married Ronnie I. Posner in 1963.

Growing up in an environment steeped in real estate and finance, Ackman developed an early interest in investing and business. The Ackman family's connection to the real estate industry in New York would later influence Bill Ackman's early career choices and his initial focus on real estate-related investments. Chappaqua, a suburb of New York City known for its highly ranked public schools, provided a stable and privileged upbringing.

Ackman has described his father as a significant influence on his career, crediting him with instilling an understanding of business and deal-making from a young age. The competitive drive and analytical temperament that would later define Ackman's approach to activist investing were evident during his formative years.

Education

Ackman attended Harvard College, where he earned a Bachelor of Arts degree. He subsequently enrolled at Harvard Business School, graduating with a Master of Business Administration (MBA). His time at Harvard shaped his intellectual framework for investing and provided him with connections to other future figures in the financial world.

Ackman's Harvard education has remained a significant part of his public identity. He has maintained ties with the university throughout his career, though in more recent years his relationship with the institution became strained amid his public criticisms of Harvard's leadership during the 2023–2024 campus controversies surrounding the Israel–Hamas war.

Career

Early Career and Gotham Partners

After completing his MBA at Harvard Business School, Ackman entered the investment world. In 1992, he co-founded Gotham Partners Management, a small investment firm, along with fellow Harvard graduate David P. Berkowitz. Gotham Partners focused on investments in public and private companies, with an emphasis on real estate-related enterprises. The firm attracted attention in the financial press for its ambitious approach, with a young Ackman quickly establishing a reputation as an aggressive and analytically rigorous investor.

Gotham Partners grew during the 1990s but eventually encountered difficulties. The firm's investments in certain illiquid assets and concentrated positions led to challenges as market conditions shifted. By the early 2000s, Gotham Partners faced investor redemption requests and regulatory scrutiny, and the firm was ultimately wound down. The experience, while painful, provided Ackman with hard-earned lessons about liquidity risk, portfolio concentration, and investor relations that would inform the structure of his next venture.

Pershing Square Capital Management

In 2004, Ackman founded Pershing Square Capital Management, which would become one of the most prominent activist hedge funds in the world. The firm's name was drawn from Pershing Square, a public plaza adjacent to Grand Central Terminal in Manhattan. Pershing Square Capital Management was structured to pursue a concentrated portfolio strategy, typically holding significant positions in a small number of publicly traded companies where Ackman identified opportunities for value creation through operational improvements, strategic changes, or governance reforms.

Pershing Square's investment approach distinguished itself through its willingness to take large, public positions and aggressively advocate for change. Ackman became known for detailed research presentations—often running dozens or even hundreds of pages—that laid out his investment theses in painstaking detail. This approach earned him a reputation as one of the most prominent activist investors of his generation.

The firm also launched Pershing Square Holdings, a closed-end fund listed on the Euronext Amsterdam exchange, giving a broader base of investors access to Ackman's strategy.

Notable Investment Campaigns

Ackman's career at Pershing Square has been defined by a series of high-profile investment campaigns, some resulting in substantial profits and others in significant losses.

One of Ackman's most successful campaigns involved Canadian Pacific Railway, where Pershing Square took a large stake and pushed for management changes. The activist campaign led to a change in leadership and a subsequent operational turnaround that produced substantial returns for Pershing Square investors.

Ackman also pursued a prominent position in J.C. Penney, the American department store chain. He took a significant stake and pushed for a radical transformation of the retailer's business model, including the hiring of a new CEO. The strategy proved unsuccessful, and Ackman ultimately resigned from the J.C. Penney board in August 2013 amid disagreements with the company's direction. The J.C. Penney investment resulted in significant losses for Pershing Square.

Perhaps Ackman's most publicly dramatic investment battle was his short position in Herbalife, the nutritional supplement company. Beginning in December 2012, Ackman made a $1 billion short bet against Herbalife, publicly labeling the company a pyramid scheme and presenting detailed research to support his thesis. The Herbalife short became one of the most watched investment battles in Wall Street history, in part because of Ackman's public feud with fellow investor Carl Icahn, who took the opposing side of the trade. The position was ultimately unsuccessful, and Ackman closed his Herbalife short at a loss after several years.

Another consequential investment was Pershing Square's involvement with Valeant Pharmaceuticals (later renamed Bausch Health). Ackman took a large position in the pharmaceutical company and joined its board of directors. Valeant's business model—centered on acquiring other pharmaceutical companies and raising drug prices—drew intense scrutiny from regulators and the media. As Valeant's stock declined sharply amid accounting questions and congressional investigations, Pershing Square suffered major losses. Ackman eventually exited the position entirely.

Despite these setbacks, Ackman's overall record at Pershing Square has included periods of exceptional performance. In 2015, his returns were sufficient to place him among the top 20 hedge fund managers by performance. Ackman also made a widely publicized and highly profitable trade at the onset of the COVID-19 pandemic in early 2020, when he purchased credit default swaps that generated approximately $2.6 billion in profits over a matter of weeks as markets plunged.

Recent Investments and AI Focus

In 2026, Ackman continued to adapt Pershing Square's portfolio to reflect evolving market themes, with a notable shift toward technology and artificial intelligence. In February 2026, Pershing Square Capital Management disclosed a new significant stake in Meta Platforms, the parent company of Facebook, Instagram, and WhatsApp. During the fund's annual investor presentation, Ackman described Meta as having a "deeply discounted valuation" and expressed confidence in the company's positioning in the AI landscape.

The Meta investment was part of a broader trend in Ackman's portfolio toward AI-related companies. His firm's 13F filings revealed additional moves into companies positioned to benefit from the growth of artificial intelligence. Ackman's Meta position drew attention from other investors and analysts, with some noting the conviction behind the large allocation.

Beyond his public market investments, Ackman also participated in private technology ventures. In January 2026, he was among a group of prominent investors—alongside Satya Nadella and the venture firm Iconiq Capital—who contributed to a $40 million funding round for Outtake, an AI security startup developing agentic AI tools.

Pershing Square IPO Efforts

In 2024, Ackman announced plans to take a portion of Pershing Square public through a U.S.-listed closed-end fund, which was expected to be one of the largest initial public offerings of its kind. The effort attracted significant attention, though the planned structure and terms evolved as market conditions and investor reception were assessed. The IPO plans reflected Ackman's ambition to expand Pershing Square's investor base and establish a more permanent capital vehicle.

Political Activities and Public Commentary

Democratic Party Ties and Shift to Republican Support

For much of his career, Ackman was a donor to Democratic candidates and organizations. However, in 2024, he endorsed Donald Trump in the 2024 United States presidential election, marking a significant public shift in his political alignment. The endorsement attracted considerable media attention given Ackman's prior associations with the Democratic Party.

Following Trump's election, Ackman continued to engage publicly with political issues, though he did not hesitate to criticize the administration when he disagreed. In January 2026, when President Trump called for a one-year 10 percent cap on credit card interest rates, Ackman publicly pushed back, calling the proposal a "mistake" and arguing it could have unintended consequences for affordability and credit access.

Ackman's political engagement also extended to immigration enforcement. In January 2026, he donated $10,000 to a GoFundMe campaign supporting Jonathan Ross, an ICE agent involved in a controversial shooting incident in Minneapolis in which a woman named Renee Nicole Good was killed. The donation drew criticism from various quarters, and Ackman publicly defended his decision.

Israel Advocacy and Higher Education Criticism

Following the October 7, 2023, attacks on Israel, Ackman became one of the most vocal public figures in the American business community advocating for Israel and criticizing what he described as antisemitism on university campuses. He was particularly critical of the 2024 pro-Palestinian protests on university campuses, arguing that the protests crossed the line from political speech into harassment and antisemitism.

Ackman's engagement with higher education issues intensified when he publicly called for the resignation of Claudine Gay, then-president of Harvard University, following her congressional testimony on campus antisemitism. His sustained public campaign, conducted largely on the social media platform X, was credited by many observers as a contributing factor in Gay's subsequent resignation.

Tax Policy Debates

Ackman's wealth and political prominence have also made him a subject in broader debates about taxation of the ultra-wealthy. In February 2026, Senator Bernie Sanders named Ackman alongside Elon Musk and Peter Thiel in remarks demanding that billionaires pay their "fair share" of taxes, specifically in the context of a proposed California wealth tax.

Personal Life

Ackman married Karen Ann Herskovitz in July 1994. Herskovitz held a degree in landscape architecture. The couple had children together before divorcing.

In 2018, it was reported that Ackman was engaged to Neri Oxman, an Israeli-American architect, designer, and professor at the MIT Media Lab known for her pioneering work at the intersection of computational design, biology, and materials science. The couple married in January 2019. Reporting on their wedding described the connection between Ackman and Oxman as one that brought together the worlds of finance and scientific research.

Ackman is Jewish and has been active in Jewish communal life and causes related to Israel.

Philanthropy

Ackman and his wife are co-founders of the Pershing Square Foundation, which supports a range of philanthropic initiatives. Ackman has been a signatory to The Giving Pledge, the commitment initiated by Warren Buffett and Bill Gates encouraging billionaires to give away the majority of their wealth to philanthropic causes during their lifetimes or in their wills. According to The Chronicle of Philanthropy, Ackman has ranked among the top American philanthropists by donation volume.

The Pershing Square Foundation has directed funds toward education, health, economic development, and human rights initiatives. Ackman's philanthropic interests have included significant support for organizations in New York City and for causes related to combating poverty.

Recognition

Ackman has been the subject of extensive media coverage throughout his career. His investment campaigns, public feuds with other investors, and outspoken commentary have made him a regular feature in financial media outlets including CNBC, Bloomberg News, and The New York Times.

The book Confidence Game: How a Hedge Fund Manager Called Wall Street's Bluff by Christine S. Richard documented one of Ackman's earlier investment campaigns and provided a detailed account of his analytical methods and tenacity in pursuing an investment thesis.

His returns at Pershing Square have placed him among the top-performing hedge fund managers over certain periods, earning recognition in industry rankings. Ackman's ability to generate public attention for his investment theses—through detailed presentations, media appearances, and social media commentary—has been a distinguishing characteristic of his career.

Legacy

Ackman's career has been characterized by the combination of concentrated, high-conviction investing with a willingness to engage in public campaigns to effect change at the companies in which he invests. His approach to activist investing—taking large stakes, publicly articulating detailed investment theses, and pushing for management or strategic changes—helped define the modern activist hedge fund model.

His successes and failures have been unusually public, lending his career a narrative arc that has attracted attention well beyond the financial industry. The Herbalife short, the Valeant investment, the J.C. Penney campaign, and the Canadian Pacific Railway turnaround represent a body of work that has been studied by investors, business school students, and financial journalists.

In recent years, Ackman's public profile has expanded beyond finance into politics and social commentary. His vocal stance on issues related to antisemitism, higher education governance, and immigration enforcement has made him a polarizing figure in American public discourse. His political evolution from a Democratic donor to a Trump supporter reflects broader shifts among some figures in the business and financial communities.

Through the Pershing Square Foundation and his commitment to The Giving Pledge, Ackman has also sought to channel his wealth toward philanthropic ends, though his public controversies have at times overshadowed these efforts.