Bill Ackman

William Ackman
Born	(1966-05-11) May 11, 1966 Chappaqua, New York, U.S.
Occupation(s)	Hedge fund manager, investor, philanthropist
Years active	1992–present
Known for	Founder and CEO of Pershing Square Capital Management; activist investing

William Albert Ackman (born May 11, 1966) is an American billionaire hedge fund manager who founded and currently leads Pershing Square Capital Management, a firm specializing in investment management. He has gained recognition as an activist investor. As of July 2025, Forbes estimated Ackman's net worth at $9.4 billion.

Ackman is also known for his philanthropic efforts and is a signatory of The Giving Pledge, committing to donate at least half of his fortune to charitable endeavors. Although historically a supporter of Democratic candidates, he endorsed Donald Trump in the 2024 United States presidential election. Additionally, he has been a vocal advocate for Israel, particularly following the October 7 attacks.

Early life and education

Raised in Chappaqua, New York, Ackman is the son of Ronnie I. (née Posner) and Lawrence David Ackman, who served as chairman of the New York-based real estate finance company Ackman-Ziff Real Estate Group. His heritage is Ashkenazi Jewish.

Ackman graduated magna cum laude from Harvard College in 1988 with a Bachelor of Arts in social studies. His undergraduate thesis was entitled "Scaling the Ivy Wall: The Jewish and Asian American Experience in Harvard Admissions." He later earned an MBA from Harvard Business School in 1992.

Gotham Partners

In 1992, Ackman co-founded Gotham Partners alongside fellow Harvard alumnus David P. Berkowitz. The firm focused on making modest investments in publicly traded companies. In 1995, Gotham teamed up with Leucadia National to bid on Rockefeller Center; although the bid was unsuccessful, it elevated Gotham's reputation, resulting in $500 million in assets under management by 1998. By 2002, Gotham faced legal disputes involving outside shareholders of companies within its portfolio.

Ackman publicly contested Standard & Poor's AAA rating on MBIA bonds in 2002. His legal team responded to a subpoena that required submission of over 700,000 pages of MBIA financial records. He pushed for the separation of MBIA’s structured finance operations from its municipal bond insurance business. Ackman highlighted that MBIA was prohibited from trading billions in credit default swaps (CDS) linked to mortgage-backed collateralized debt obligations (CDOs), which were instead handled by LaCrosse Financial Products, an entity he described as an "orphaned transformer." During the 2008 financial crisis, Ackman profited by purchasing CDS protection against MBIA corporate debt and closed out his short position in January 2009.

In 2003, Ackman became involved in a conflict with Carl Icahn regarding an investment transaction involving Hallwood Realty shares. Ackman sold $4.5 million worth of shares to Icahn under a "schmuck insurance" arrangement: if Icahn sold within three years and realized gains exceeding 10%, profits would be shared. When Hallwood was acquired in 2004 at $136.16 per share, Icahn refused to compensate Ackman his portion, arguing the merger did not constitute a sale. After litigation, a court ruled in 2011 that Icahn owed Ackman $4.5 million plus interest and legal fees amounting to $9 million.

Pershing Square Capital Management

In 2004, Ackman established Pershing Square Capital Management using $54 million sourced from his own capital and Leucadia National.

By 2010, Pershing Square had acquired an 18% stake in J. C. Penney through the purchase of 39 million shares at an average cost of $22 per share. After dedicating two years to attempting a turnaround of the retailer, Ackman stepped down from the board in August 2013 due to conflicts with fellow directors.

As of January 2015, LCH Investments placed Ackman among the top 20 hedge fund managers worldwide following Pershing Square’s net profits of $4.5 billion in 2014, bringing total lifetime gains since inception to $11.6 billion.

On April 27, 2016, Ackman appeared before the U.S. Senate Special Committee on Aging alongside outgoing Valeant Pharmaceuticals CEO J. Michael Pearson and interim CEO Howard Schiller to address concerns about Valeant’s pricing policies and corporate strategy. Ackman admitted that his investment represented support for Valeant’s business model. He ultimately divested his remaining 27.2 million shares in March 2017 for roughly $300 million, closing a position initially costing about $4.6 billion and resulting in significant losses.

In early 2024, Ackman aimed to raise $25 billion through an IPO for Pershing Square but retracted the offering on August 1 after securing only $2 billion. He announced intentions to relaunch the fund with a modified "transaction structure."

Ackman held the role of chairman at Howard Hughes Holdings, one of Pershing Square’s longest-standing investments, from 2010 until his departure from its board in 2024.

Herbalife short

In December 2012, Ackman revealed a $1 billion short position by Pershing Square against Herbalife, a company specializing in weight-loss and nutritional supplements, branding it as a "pyramid scheme." Soon after, billionaire investor Carl Icahn publicly disputed Ackman’s allegations during a CNBC interview and proceeded to acquire a substantial stake in Herbalife by January 2013. Over time, Icahn increased his holdings to counterbalance Ackman’s short position.

Pershing Square initiated an extensive public relations campaign aimed at pressuring regulatory bodies to investigate Herbalife. This included hiring lobbying firms, organizing protests, and coordinating letter-writing campaigns. Ackman also collaborated with groups identifying purported victims and personally lobbied senators who subsequently contacted federal regulators. These efforts led to investigations by the Federal Trade Commission and other agencies. In April 2014, the FBI reportedly launched a probe into Herbalife, examining documents from former distributors. By March 2015, federal prosecutors and the FBI investigated whether individuals hired by Ackman provided false statements intended to prompt investigations and depress Herbalife’s stock price; however, neither Ackman nor Pershing Square were subpoenaed. These inquiries ultimately found insufficient evidence and were closed.

Several federal and state agencies determined that Herbalife engaged in improper conduct. In July 2016, Herbalife reached a settlement with the FTC agreeing to pay $200 million and restructure its operations to avoid classification as a pyramid scheme. The FTC concluded that Herbalife misled consumers and that top earners primarily profited through recruiting new distributors. In 2019, Herbalife paid $20 million to resolve SEC charges concerning deceptive statements about its activities in China. The following year, it paid over $122 million after DOJ and SEC investigations uncovered falsified records and corrupt payments to Chinese officials aimed at expanding its business there. In 2022, Herbalife settled for $12.5 million over alleged violations of the RICO statutes.

In November 2017, Ackman announced he had closed his short position but maintained bearish bets on Herbalife through put options. By February 28, 2018, he fully exited this near-billion-dollar wager at a loss.

COVID-19 response

Prior to the 2020 stock market crash, Ackman safeguarded Pershing Square’s holdings by allocating $27 million toward credit protection, effectively insuring against significant market declines. This hedge was publicly revealed by Pershing Square on March 3, 2020. Rather than liquidating strong portfolio assets, Ackman opted for a hedging approach. This tactic yielded substantial returns, generating $2.6 billion in less than a month.

During a March 18, 2020 interview with CNBC, Ackman advocated for a "30-day shutdown" of the U.S. economy to limit the coronavirus spread and reduce economic fallout. He cautioned that hotel industry stocks risked collapsing entirely without decisive action and recommended companies suspend stock repurchase programs due to anticipated market instability.

Ackman encountered criticism for acquiring discounted equity positions in firms he had cautioned might fail; nonetheless, he had already secured roughly half of his profits prior to the CNBC appearance.

In November 2020, Ackman disclosed that his heightened awareness of COVID-19’s potential impact was partly inspired by viewing the film Contagion.

Investment style

Ackman has emphasized that his most lucrative investments tend to be contentious, adhering to his primary activist investing principle: "make a bold call that nobody believes in."

Among his notable investment maneuvers are shorting MBIA bonds during the 2008 financial crisis, engaging in a proxy battle with Canadian Pacific Railway, and acquiring major positions in Target Corporation, Valeant Pharmaceuticals, and Chipotle Mexican Grill. Between 2012 and 2018, Ackman maintained a $1 billion short position against nutrition company Herbalife, which he characterized as a pyramid scheme disguised as a multi-level marketing operation. This campaign was documented in Betting on Zero.

Following underwhelming returns from 2015 through 2018, Ackman revamped Pershing Square’s leadership. In 2019, the fund posted a 58.1% return, ranking it among the top-performing hedge funds globally.

Some detractors have labeled Ackman an Business oligarch, accusing him of manipulating markets and using his financial influence to affect policy decisions, particularly concerning Israel.

Philanthropy

As a member of The Giving Pledge, Ackman has committed to donating no less than half of his fortune to philanthropic endeavors. In 2006, he and then-wife Karen established the Pershing Square Foundation to back initiatives in economic development, education, healthcare, human rights, arts, and urban renewal. Since its founding, the foundation has distributed over $750 million to upwards of 100 organizations such as One Acre Fund, Saïd Business School’s Oxford-Pershing Square Graduate Scholarships, Cold Spring Harbor Laboratory, Center for Jewish History, Innocence Project, African Parks, and Planned Parenthood. By 2024, Ackman and his spouse Neri Oxman serve as co-trustees.

Ackman earned spots on The Chronicle of Philanthropy's "Philanthropy 50" list in both 2011 and 2021 for his substantial charitable donations.

On March 15, 2021, he contributed 26.5 million shares of Coupang—a South Korean e-commerce firm—valued at $1.36 billion, distributing them among three recipients including his foundation.

In December 2022, Ackman auctioned a charitable lunch in collaboration with the David Lynch Foundation to benefit New York’s frontline healthcare personnel, law enforcement officers, and veterans facing mental health issues. The winning bid was $210,000, which Ackman matched with an equal donation.

Ackman publicly expressed support for biologist David M. Sabatini after allegations led to Sabatini’s exit from MIT and affiliated institutions. In February 2023, Ackman announced that the Pershing Square Foundation alongside an anonymous benefactor would jointly provide $25 million over five years to establish a new research lab for Sabatini.

Support of Israel

Bill Ackman has openly expressed his backing for Israel's military actions during the Gaza war.

After the October 7 Hamas-led attack on Israel, multiple student organizations at Harvard condemned Israeli government statements and attributed responsibility for the conflict to Israeli policies. Their letter urged Harvard to take action against what they termed the "annihilation of Palestinians". In reaction, Ackman requested a list of all students who signed this letter to ensure his firm and others would not "accidentally employ" them. He maintained that those endorsing terrorist acts should not conceal their identities within corporate recruitment. His position garnered support from other executives like Jonathan Neman. However, former Harvard president Lawrence Summers denounced Ackman's request as reminiscent of McCarthyism.

Ackman was part of a WhatsApp group consisting of Israeli military officials and American business leaders focused on "shifting the narrative" to favor Israel by emphasizing Hamas's atrocities and endorsing Israel’s military campaign amid U.S. demonstrations opposing the Gaza war. This group collaborated closely with Israeli figures including former prime minister Naftali Bennett and ambassador Michael Herzog. They coordinated screenings of "Bearing Witness to the October 7th Massacre," a documentary featuring footage collected by the Israeli Defense Forces depicting Hamas killings; these events were held in New York City and at Harvard.

In April 2024, members of this group conducted a video conference with New York City Mayor Eric Adams advocating for police intervention during pro-Palestinian protests at Columbia University. Discussions also involved potential political contributions to Adams. A spokesperson for Ackman confirmed he had not engaged with the group since January 10, 2024, denying any conversations with Adams regarding protest policing or campaign donations.

In November 2023, Ackman voiced support for Elon Musk after Musk defended antisemitic remarks made by an X user falsely accusing Jewish communities of fostering "dialectical hatred against whites," describing Musk’s statements as spontaneous commentary. That same month, Ackman launched a campaign demanding the removal of Harvard president Claudine Gay, criticizing her handling of antisemitism allegations and raising plagiarism concerns.

On January 3, 2024, Business Insider disclosed that Ackman's wife, Neri Oxman, had committed plagiarism in portions of her dissertation; she subsequently issued an apology citing "citation errors". Following this revelation, Ackman vowed to investigate plagiarism among MIT faculty members, including MIT president Sally Kornbluth, who had appeared alongside Gay at a congressional hearing addressing antisemitism.

On June 14, 2025, Ackman posted on Twitter urging the United States to join Israel in its conflict against Iran. He highlighted this moment as a strategic chance to dismantle Iran’s nuclear capabilities without deploying ground forces.

US politics

Ackman has consistently contributed to Democratic candidates and groups, including Richard Blumenthal, Chuck Schumer, Robert Menendez, the Democratic National Committee, and the Democratic Senatorial Campaign Committee. Although he backed Michael Bloomberg in the 2016 presidential race, he ultimately cast his vote for Donald Trump that year.

During the 2024 presidential primaries, Ackman threw his support behind Congressman Dean Phillips for the Democratic nomination. Phillips later mentioned potential Cabinet positions for both Ackman and Elon Musk. After Phillips ended his campaign, Ackman shifted his support to Robert F. Kennedy Jr.’s presidential run. In April 2024, Ackman declared he would not back Joe Biden due to what he perceived as Biden’s insufficient support for Israel and indicated he might vote for Trump. Following the July 2024 assassination attempt on Trump, Ackman officially endorsed him.

In a January 2024 interview, Ackman expressed that he no longer wished to be affiliated with the Democratic Party or any political party. In July 2025, after Tucker Carlson highlighted Ackman’s net worth and societal impact on Turning Point USA, Ackman responded on social media by discussing his background and journey to wealth.

Personal life

Ackman wed landscape architect Karen Ann Herskovitz on July 10, 1994. The couple has three children but separated in December 2016. In 2018, Ackman became engaged to Israeli-American designer Neri Oxman; they married in January 2019 at Manhattan’s Central Synagogue. Their first child together was born in spring 2019.

By 2017, Ackman owned a Gulfstream G550 business jet and a $90 million penthouse in Manhattan, along with other residential holdings.

Tennis

Ackman is an amateur tennis enthusiast who played on his high school team and competed in junior tournaments across the U.S. and Europe at a recreational level. In 2015, he won the Finance Cup, an amateur competition for banking and investment professionals. Throughout the 2010s, Ackman sponsored professional player Frances Tiafoe.

In a 2020 Bloomberg interview, he claimed he could hold his own in doubles against John McEnroe. By 2023, Ackman led a group aiming to secure a leadership position in professional tennis via a proposed $150 million equity stake in the WTA Tour. As of July 2025, he remarked that he was playing "the best tennis of my life."

After previous financial contributions to the International Tennis Hall of Fame, Ackman received a wild card entry into the 2025 Hall of Fame Open at age 59 but was defeated in doubles alongside Jack Sock by Omar Jasika and Bernard Tomic. This appearance sparked criticism from tennis fans and professionals alike. Analysts such as USA Today's Dan Wolken and former pro Andy Roddick questioned whether granting a wild card to Ackman was appropriate, raising concerns about meritocracy and competitive fairness. In response, Ackman challenged Roddick to a doubles match.

The Hall of Fame Open characterized Ackman's participation as “a learning experience” to inform future decisions. After the tournament, Ackman offered a $10 million endowment to the International Tennis Hall of Fame, which declined; subsequently, he donated $10 million to the Junior Tennis Champions Center, which accepted the gift.

Additional reading

• Richard, Christine. Confidence Game (Wiley, 2010) in collaboration with Bloomberg News.