Bill Ackman


William Albert Ackman is an American billionaire hedge fund manager who is the founder and chief executive of Pershing Square Capital Management, an investment management company. He has been described as an activist investor. As of July 2025, Ackman's net worth was estimated at $9.4 billion by Forbes.
A long-time donor to Democratic candidates and organizations, Ackman endorsed Donald Trump in the 2024 United States presidential election. Ackman has been an active supporter of Israel, particularly following the October 7 attacks, criticizing the 2024 pro-Palestinian protests on university campuses.

Early life and education

Ackman was raised in Chappaqua, New York, the son of Ronnie I. and Lawrence David Ackman, the former chairman of a New York real estate financing firm, Ackman-Ziff Real Estate Group. He is of Ashkenazi Jewish descent.
He graduated from Horace Greeley High School in 1985. In 1988, he received a Bachelor of Arts degree magna cum laude in social studies from Harvard College. His thesis was titled "Scaling the Ivy Wall: The Jewish and Asian American Experience in Harvard Admissions". In 1992, he received a Master of Business Administration degree from Harvard Business School.

Career

Gotham Partners

In 1992, Ackman founded the investment firm Gotham Partners with fellow Harvard graduate David P. Berkowitz. The firm made small investments in public companies. In 1995, Ackman partnered with the insurance and real estate firm Leucadia National to bid for Rockefeller Center. Although they did not win the deal, the bid generated interest in Gotham from investors: three years later, Gotham had $500 million in assets under management. By 2002, Gotham had become entrenched in litigation with various external shareholders who also owned an interest in the companies in which Gotham invested.
In 2002, Ackman researched MBIA in order to challenge Standard & Poor's AAA rating of its bonds. At a billed cost of more than $100,000, his law firm copied 725,000 pages of statements regarding the financial services company to comply with a subpoena. Ackman called for a division between MBIA's structured finance business and its municipal bond insurance business.
He argued that MBIA was legally restricted from trading billions of dollars of credit default swap protection that it had sold against various mortgage-backed collateralized debt obligations, and was using a second corporation, LaCrosse Financial Products, which MBIA described as an "orphaned transformer." Ackman bought credit default swaps against MBIA corporate debt and sold them for a large profit during the 2008 financial crisis. He reported covering his short position on MBIA on January 16, 2009, according to the 13D filed with the SEC.
In 2003, a feud developed between Ackman and Carl Icahn over an investment deal. Ackman sued Icahn for his share of profits in a stock sale, and in 2011, Icahn was forced to pay the $4.5 million plus 10% interest per year and legal fees, totaling $9 million.

Pershing Square Capital Management

In 2004, with $54 million from his personal funds and from his former business partner Leucadia National, Ackman started Pershing Square Capital Management.
In 2010, Pershing started buying J. C. Penney shares, paying an average of $22 for 39 million shares or 18% of J.C. Penney's stock. In August 2013, the two-year campaign to transform the department store came to an abrupt end when Ackman stepped down from the board following a disagreement with fellow board members.
In 2011, Pershing Square began acquiring shares of Canadian Pacific Railway, eventually becoming the railway's largest shareholder. In November of that year, citing the company's poor financial performance, Ackman initiated a proxy contest with the goal of replacing CP's CEO and multiple board members. At the railway's annual meeting in May 2012, close to 90 percent of shareholder votes supported Ackman's dissident slate and much of the company's leadership was subsequently replaced. Following the successful proxy contest, The Globe and Mail's Report on Business Magazine named Ackman "CEO of the Year," stating that "no other CEO has had a bigger impact on how our publicly traded companies are steered than Ackman."
In January 2015, LCH Investments 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 launch in 2004 through 2014.
On April 27, 2016, Ackman, along with Valeant Pharmaceuticals' outgoing CEO, J. Michael Pearson, and the company's former interim CEO, Howard Schiller, testified before the United States Senate Special Committee on Aging. The testifying panel answered questions related to the committee's concerns about repercussions to patients and the health care system posed by Valeant's business model and controversial pricing practices. Ackman sold his remaining 27.2 million share position in Valeant for about $300 million in March 2017 in what constituted a substantial loss. In 2017, Pershing Square paid $193.75 million to a group of Allergan shareholders as part of a $290 million settlement.
In 2016, Ackman began investing in Chipotle Mexican Grill, and the company was among Pershing Square's top holdings from 2017 to 2024. Ackman was credited with helping Chipotle rebound from years of losses by playing a part in hiring Brian Niccol as CEO in 2018.
In 2021, Pershing Square acquired a 10 percent stake in Universal Music Group and, as of 2025, it is one of Pershing Square's largest positions. Prior to the initial investment, Ackman told Universal management that his grandfather, Herman Ackman, wrote a hit song in 1926 on Tin Pan Alley. It was later discovered that the song's recordings were owned by Universal, which then mounted and framed phonograph records and sheet music as a gift to Ackman. Ackman became a member of the company's board of directors in 2022, a position he retained until 2025.
In early 2024, Ackman aimed to raise capital to take a new fund known as Pershing Square USA public. However, after securing only $2 billion, he decided to withdraw the IPO on August 1, 2024. He announced plans to relaunch a version of the fund with a new "transaction structure."
Ackman was chairman of Howard Hughes Holdings, one of Pershing's longest-held investments, from 2010 until 2024, when he stepped down from its board. In May 2025, Ackman rejoined the board as Executive Chairman after Pershing Square increased its investment in the company to 47%.

Herbalife short

In December 2012, Ackman announced that Pershing Square had made a $1 billion short bet against Herbalife, a maker of weight-loss and vitamin supplements, calling the company a "pyramid scheme".
A few months after Ackman's initial comments, billionaire investor Carl Icahn challenged Ackman's comment during a dual appearance by Ackman and Icahn on CNBC, during which both men insulted each other. Following this, Icahn announced a stake in Herbalife in January 2013. Over the following years, Icahn continued to buy Herbalife shares to combat Ackman's short.
Ackman's Pershing Square funded a persistent public relations campaign against Herbalife in an attempt to pressure state and federal regulators to investigate the company. He hired numerous lobbying firms, and had his team organize protests and letter writing campaigns. Ackman also paid organizations to help find victims of Herbalife, and personally lobbied Senator Linda Sánchez and the office of Senator Ed Markey, both of whom later sent letters to federal regulators. Following this campaign, the Federal Trade Commission initiated an investigation into Herbalife. Other regulators and law enforcement also got involved. In April 2014, Reuters reported that the FBI conducted a probe into Herbalife and reviewed documents obtained from the company's former distributors. On March 12, 2015, it was reported that federal prosecutors and the FBI were probing whether some people hired by Ackman made false statements in an attempt to encourage investigations and lower Herbalife's stock; Ackman was quoted that he would not back down from his claims against Herbalife. Neither Ackman nor Pershing Square were subpoenaed. The FBI probes affecting Herbalife and Ackman both failed to find sufficient evidence and were not pursued further.
Multiple Federal and State agencies found that Herbalife committed wrongdoing. In July 2016, Herbalife settled with the Federal Trade Commission, agreeing to pay $200 million and restructure its business practices in exchange for avoiding being labelled as a pyramid scheme. The FTC found that Herbalife "deceived consumers" and that "the small minority of distributors who do make a lot of money are compensated for recruiting new distributors." In 2019, Herbalife paid the SEC $20 million to settle charges that it made false and misleading statements about its China business model. In 2020, Herbalife paid more than $122 million after the Department of Justice and SEC found Herbalife "falsif books and records and provide corrupt payments and benefits to Chinese government officials for the purpose of obtaining, retaining, and increasing Herbalife's business in China." In 2022, Herbalife paid $12.5 million settled a case of alleged RICO violations.
In November 2017, Ackman said that he had covered his short-sell position, but would continue to bet against Herbalife using put options. On February 28, 2018, Ackman exited his near billion-dollar bet against Herbalife at a loss.

COVID-19 response

Ahead of the 2020 stock market crash, Ackman hedged Pershing Square's portfolio, investing $27 million to purchase credit protection, insuring the portfolio against steep market losses. Pershing Square first disclosed the hedge on March 3, 2020. According to Reuters, "Ackman said hedging was preferable to selling off his portfolio of companies whose businesses are otherwise strong." The hedge was effective, generating $2.6 billion in less than one month.
On March 18, 2020, in a phone interview with CNBC, Ackman called upon President Donald Trump for a "30-day shutdown" of the American economy to slow the spread of coronavirus and minimize loss of life and ensuing economic destruction resulting from the shutdown. Ackman warned that without intervention, hotel stocks were "going to zero" and said that America could "end as we know it". He also cautioned U.S. companies to stop stock buyback programs because "hell is coming".
Ackman later received criticism for actively buying discounted equity stakes in the very companies he was warning could fail; however, Ackman already had realized roughly half of the gains before appearing during the CNBC interview.
In a November 2020 interview, Ackman said that he had grown concerned about COVID-19 because he had seen the film Contagion.