History of Bill Ackman in Timeline

By Popular Timelines Editorial Team · Updated: July 19, 2026

Bill Ackman is a prominent American billionaire investor and the founder and CEO of Pershing Square Capital Management. He is widely recognized for his activist investing style, where he takes significant stakes in companies to advocate for operational or management changes to unlock shareholder value. Throughout his career, Ackman has been involved in several high-profile financial campaigns, including his notable short position against Herbalife and his successful long-term investment in Canadian Pacific Railway. Beyond his investment firm, Ackman is known for his public commentary on economic policy, corporate governance, and various social issues, frequently utilizing social media to influence discourse. His investment strategy often involves concentrated portfolios and deep research, making him one of the most influential figures on Wall Street. Despite periods of volatility in his fund's performance, he remains a key figure in modern finance and a vocal advocate for his investment theses.

Sections (5)

Full Timeline Early Life & Education Career & Achievements Challenges & Struggles Controversies & Scandals

1926: Herman Ackman writes a hit song

In 1926, Bill Ackman's grandfather, Herman Ackman, composed a hit song while working on Tin Pan Alley.

May 11, 1966: Birth of William Albert Ackman

On May 11, 1966, William Albert Ackman, the future billionaire hedge fund manager and founder of Pershing Square Capital Management, was born.

Others born on this day/year

1985: Graduation from Horace Greeley High School

In 1985, Bill Ackman completed his secondary education by graduating from Horace Greeley High School.

1988: Bachelor of Arts from Harvard College

In 1988, Bill Ackman earned a Bachelor of Arts degree magna cum laude in social studies from Harvard College, having written a thesis on Harvard's admission experiences.

1992: Founding of Gotham Partners

In 1992, Bill Ackman co-founded the investment firm Gotham Partners alongside David P. Berkowitz, focusing on making small investments in public companies.

1992: Master of Business Administration from Harvard Business School

In 1992, Bill Ackman furthered his academic credentials by obtaining a Master of Business Administration degree from Harvard Business School.

1995: Bid for Rockefeller Center

In 1995, Bill Ackman partnered with Leucadia National to place a bid on Rockefeller Center; while unsuccessful, the effort raised the profile of Gotham Partners and helped grow their assets under management significantly.

2002: Gotham Partners Litigation

By 2002, the investment firm Gotham Partners became heavily involved in legal conflicts and litigation with other shareholders who shared interests in the firm's portfolio companies.

2002: Challenge to MBIA Credit Rating

In 2002, Bill Ackman conducted extensive research into MBIA to contest the AAA bond rating provided by Standard & Poor's. During this process, his legal team incurred over $100,000 in costs to process 725,000 pages of financial documents under subpoena, and Ackman publicly advocated for the structural separation of MBIA's municipal bond and structured finance divisions.

2003: Feud with Carl Icahn

In 2003, a significant financial disagreement emerged between Bill Ackman and investor Carl Icahn regarding an investment deal, leading Ackman to initiate a lawsuit against Icahn to recover his portion of profits from a specific stock sale.

2004: Founding of Pershing Square Capital Management

In 2004, Bill Ackman established the investment firm Pershing Square Capital Management by leveraging $54 million derived from his own personal capital and funding provided by his former business partner, Leucadia National.

2004: Launch of Pershing Square

In 2004, the hedge fund Pershing Square was launched, marking the start of a decade-long period that resulted in $11.6 billion in lifetime gains by the end of 2014.

2008: Profiting from MBIA Credit Default Swaps

During the 2008 financial crisis, Bill Ackman achieved significant profits by purchasing credit default swaps against the corporate debt of MBIA, a move he capitalized on by selling them at a favorable time.

2008: Shorting MBIA Bonds

During the 2008 financial crisis, Bill Ackman engaged in a notable market maneuver by shorting the bonds of MBIA, a financial services company.

January 16, 2009: Closure of MBIA Short Position

On January 16, 2009, Bill Ackman formally reported that he had covered his short position on MBIA, as disclosed in a 13D filing submitted to the United States Securities and Exchange Commission.

2010: Appointment as Chairman of Howard Hughes Holdings

In 2010, Bill Ackman took on the role of chairman for Howard Hughes Holdings, marking the beginning of a long-term investment period for Pershing Square.

2010: Pershing Square Invests in J. C. Penney

In 2010, Bill Ackman's firm, Pershing Square, began acquiring a significant stake in the department store chain J. C. Penney, eventually purchasing 39 million shares at an average price of $22 per share, which represented 18% of the company.

2011: Initiation of Canadian Pacific Railway Proxy Contest

In 2011, Bill Ackman's firm, Pershing Square, started accumulating shares in the Canadian Pacific Railway. By November 2011, citing lackluster financial performance, Ackman launched a proxy contest to overhaul the company's leadership team, specifically targeting the CEO and board members.

2011: Legal Victory Against Icahn

In 2011, the legal dispute concluded with Carl Icahn being ordered to pay Bill Ackman $4.5 million, which, along with 10% annual interest and legal fees, resulted in a total payout of $9 million to Ackman.

May 2012: Victory in Canadian Pacific Railway Shareholder Vote

During the annual meeting in May 2012, Ackman secured a decisive victory as approximately 90 percent of shareholders voted in favor of his proposed slate of candidates, leading to a significant replacement of the railway's leadership.

December 2012: Short Bet Against Herbalife

In December 2012, Bill Ackman announced that his firm, Pershing Square, had executed a $1 billion short position against Herbalife, publicly characterizing the supplement company as a pyramid scheme.

2012: Initiation of Herbalife Short Position

In 2012, Bill Ackman began a high-profile one billion dollar short position against Herbalife, publicly denouncing the organization as a pyramid scheme.

January 2013: Carl Icahn Announces Herbalife Stake

Following a heated public confrontation on CNBC, investor Carl Icahn announced in January 2013 that he had purchased a stake in Herbalife, effectively opposing Ackman's short position.

August 2013: Ackman Resigns from J. C. Penney Board

In August 2013, Bill Ackman ended his two-year campaign to restructure J. C. Penney by resigning from the company's board of directors following internal conflicts with other board members.

April 2014: FBI Investigation into Herbalife

In April 2014, it was reported by Reuters that the FBI had initiated an investigation into Herbalife, which involved the review of documents gathered from the company's former distributors.

2014: Pershing Square Financial Gains

Throughout 2014, Pershing Square generated $4.5 billion in net gains for its investors, contributing significantly to the firm's historical performance.

January 2015: LCH Investments Top 20 Hedge Fund Manager Recognition

In January 2015, LCH Investments officially recognized Bill Ackman as one of the top 20 hedge fund managers in the world following the impressive performance of his firm.

March 12, 2015: Probe into Pershing Square Tactics

On March 12, 2015, reports surfaced that federal authorities and the FBI were investigating whether individuals hired by Bill Ackman provided false information to regulators in an attempt to manipulate Herbalife's stock price.

2015: Start of Period of Weak Performance

Starting in 2015, Bill Ackman's firm, Pershing Square, entered a challenging period characterized by weak financial returns.

April 27, 2016: Testimony before the U.S. Senate Special Committee on Aging

On April 27, 2016, Bill Ackman appeared before the United States Senate Special Committee on Aging alongside J. Michael Pearson and Howard Schiller to address concerns regarding the business practices and drug pricing strategies of Valeant Pharmaceuticals.

2016: Initial investment in Chipotle

In 2016, Bill Ackman began his investment journey with Chipotle Mexican Grill, initiating a stake in the company through Pershing Square.

March 2017: Divestment of Valeant Pharmaceuticals Shares

In March 2017, Bill Ackman sold his final 27.2 million shares of Valeant Pharmaceuticals for approximately $300 million, resulting in a significant financial loss for his firm.

August 2017: Acquisition and Proxy Fight for ADP

In August 2017, Bill Ackman purchased an 8% stake in Automatic Data Processing (ADP) and initiated a proxy battle to secure three seats on the company's board of directors.

November 2017: Adjustment of Herbalife Short-Sell Position

In November 2017, Bill Ackman announced that he had covered his primary short-sell position regarding Herbalife, though he clarified his intention to maintain bearish exposure through the use of put options.

2017: Chipotle becomes a core holding

Starting in 2017, Chipotle Mexican Grill solidified its position as one of the top holdings within Bill Ackman's Pershing Square portfolio.

February 28, 2018: Full Exit from Herbalife Short Position

On February 28, 2018, Bill Ackman officially closed out his long-standing, near-billion-dollar short position against the company Herbalife, resulting in a financial loss.

2018: Conclusion of Herbalife Short Position

By 2018, Bill Ackman concluded his significant multi-year short position against the nutrition firm Herbalife, a battle which was later documented in the film Betting on Zero.

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2018: Conclusion of Financial Underperformance

By 2018, the firm's period of weak market performance came to an end, prompting Ackman to restructure the management of Pershing Square.

2018: Appointment of Brian Niccol

In 2018, Bill Ackman played a pivotal role in the corporate turnaround of Chipotle Mexican Grill by facilitating the hiring of Brian Niccol as the company's new CEO.

2019: Exit from ADP Investment

After losing the proxy fight that lasted three months, Bill Ackman concluded his investment in Automatic Data Processing by selling his remaining shares in 2019.

2019: Pershing Square's Strong Market Rebound

In 2019, following management changes, Pershing Square achieved a 58.1% return, leading Reuters to categorize it as one of the world's best-performing hedge funds for that year.

March 3, 2020: Pershing Square Discloses Market Hedge

On March 3, 2020, Bill Ackman's firm, Pershing Square, publicly disclosed a hedging strategy initiated to protect its portfolio against potential market downturns. By investing $27 million in credit protection, Ackman successfully hedged the portfolio, ultimately generating $2.6 billion in returns in less than a month during the 2020 stock market crash.

March 18, 2020: Call for Economic Shutdown during COVID-19

On March 18, 2020, Bill Ackman gave an emotional interview on CNBC urging President Donald Trump to initiate a 30-day shutdown of the U.S. economy to mitigate the impacts of the coronavirus pandemic, warning of severe economic consequences including failing hotel stocks and urging companies to halt stock buybacks.

November 2020: Concerns Regarding COVID-19 Inspired by Contagion

In a November 2020 interview, Bill Ackman revealed that his apprehension regarding the COVID-19 pandemic was significantly influenced by his viewing of the 2011 film Contagion.

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2021: Pershing Square acquires stake in Universal Music Group

In 2021, Pershing Square finalized the acquisition of a 10 percent ownership stake in Universal Music Group.

2022: Ackman joins Universal Music Group board

In 2022, Bill Ackman was appointed as a member of the board of directors at Universal Music Group.

August 1, 2024: Withdrawal of Pershing Square USA IPO

On August 1, 2024, Bill Ackman officially withdrew the initial public offering for his new fund, Pershing Square USA, after failing to secure more than $2 billion in capital, and subsequently signaled his intent to pursue a revised transaction structure for a future launch.

2024: End of investment period

By 2024, Chipotle Mexican Grill concluded its tenure as one of the primary assets held by Pershing Square under the guidance of Bill Ackman.

2024: Resignation from Howard Hughes Holdings Board

In 2024, Bill Ackman concluded his tenure as chairman by stepping down from the board of Howard Hughes Holdings.

2024: Bill Ackman Endorses Donald Trump and Addresses Geopolitical and Campus Issues

In 2024, Bill Ackman, historically a donor to Democratic causes, shifted his political stance by endorsing Donald Trump for the United States presidency. Additionally, in 2024, Ackman maintained a strong public stance in support of Israel following the October 7 attacks and vocalized criticism regarding pro-Palestinian protest movements occurring on various university campuses.

May 2025: Rejoining Howard Hughes Holdings as Executive Chairman

During May 2025, Bill Ackman returned to the board of Howard Hughes Holdings to serve as Executive Chairman following an increase in Pershing Square's stake in the company to 47%.

2025: Universal Music Group holding update

As of 2025, Universal Music Group continues to be one of the largest investment positions for Pershing Square, following the conclusion of Ackman's board tenure.

April 2026: Net worth estimation

As of April 2026, Bloomberg estimated Bill Ackman's net worth to be approximately $8 billion, reflecting his status as a major figure in the investment management industry.