With a net worth of $9.3 billion, Bill Ackman is more than a one-percenter -- he's No. 311 on Forbes' List of Billionaires. The billionaire hedge fund manager is an activist investor through Pershing Square Capital Management, the company he founded and runs.
Activist investors buy large interests in underperforming companies and use their influence as major shareholders to pressure company leaders into managing the business differently. This article will explore Ackman's success and investing philosophy. Keep reading to learn all about him.

Primary role
Primary role
- Founder, Pershing Square Capital Management
- Former founder, Gotham Partners
Investment style
Investment strategy
Bill Ackman is a famous investor primarily known as an activist investor, meaning he scoops up large shares in companies that are often undervalued or mismanaged and uses his influence to increase shareholder value and the company's stock price.
Ackman's first big win was a position he opened with Gotham Partners. In 2002, Gotham bet on the failure of municipal bond insurer MBIA with a leveraged short position and credit default swaps (CDS). Gotham also published a report arguing that MBIA did not deserve its AAA credit rating, prompting a probe by the U.S. Securities and Exchange Commission (SEC).
Ackman's doomsday prediction for MBIA focused on the company's exposure to subprime mortgage-backed securities. Although his warnings were largely ignored, he continued his crusade against MBIA for six years while growing his investment in the company's failure.
As it turned out, Ackman got the last laugh. MBIA collapsed during the 2007-2009 financial crisis. By 2009, Ackman had closed out his position and earned $1.4 billion in the process. The deal made him one of the most famous investors on Wall Street once again.
Over the next several years, Pershing would also make billion-dollar profits on investments in Canadian Pacific Kansas City (CP -0.11%) and mall operator General Growth Properties. His style can be generally described as holding large positions in small groups of large-cap value stocks.
Career highlights
Career highlights
- Opened Gotham Partners in 1992 with partner David Berkowitz.
- Opened Pershing Square Capital Management in 2004.
- Famously shorted MBIA and warned against the company's credit rating. The company's eventual fall earned him $1.4 billion in 2009.
- Turned Canadian Pacific Railway around after acquiring a 14.2% stake, installing a new CEO, and reimagining the company's business strategy in 2011.
- Invested $27 million in CDS in early 2020, banking on debt markets faltering in the pandemic. He walked away with $2.6 billion that same year.
Philosophy & legacy
Philosophy & legacy
As an activist investor, Ackman's primary driving philosophy centers on the idea that some companies are simply poorly managed or undervalued, and by making large investments in these companies, he can influence them and help turn them around. Although he primarily takes long positions, he has also made a lot of money on shorts, including the short of MBIA, which he was convinced was not being properly rated.
Investing is a business where you can look very silly for a long period of time before you are proven right.Bill Ackman
He hasn't published any books, but he has been very active on social media, especially X, where he has influenced millions of followers. Although no prominent investors have outright claimed that his influence has affected their investment decisions, his approach to activist investing has influenced many companies and how they conduct business.
He has also recently been using his social media clout to push for the dissolution of diversity, equity, and inclusion (DEI) programs and to support other conservative talking points and candidates.
Awards & honors
Awards, honors, & recognition
2025 -- University of Haifa Honorary Doctorate
2025 -- Patriot Award from the Navy SEAL Foundation
2025 -- Rang the bell at the Tel Aviv Stock Exchange
Related investing topics
Personal notes
Personal notes
In conjunction with the Columbia Business School, Ackman and Pershing Square launched the Pershing Square Value Investing and Philanthropy Challenge in 2008.
This challenge provides students with hands-on experience in selecting, researching, and pitching investment ideas. Students are then judged on the quality of both ideas and research, as well as the pitch delivery, by the same standards an investment committee would hold them to if it were a real-life pitch.
Pershing Square Philanthropies also awards two annual prizes in life sciences:
- The Pershing Square Sohn Cancer Prize: designed to support and establish a pipeline for early-stage biomedical investments that contribute to the fight against cancer
- The MIND (Maximizing Innovation in Neuroscience Discovery) Prize: seeks groundbreaking research ideas for neurodegenerative diseases
Each prize awards $250,000 per year for three years, for a total of $750,000.
FAQ
Bill Ackman: FAQ
How did Bill Ackman make his money?
Ackman made his money as a professional investor and hedge fund manager, first with Gotham Partners and later with Pershing Square Capital Management.
What does Pershing Square invest in?
Pershing Square invests in large-cap value stocks and opportunistic hedges, such as short positions.
How much is Ackman worth?
Ackman is worth more than $9 billion.
What stocks does Bill Ackman own?
Ackman owns Alphabet, Brookfield Corporation, railway operator Canadian Pacific Kansas City, Chipotle Mexican Grill, auto rental company Hertz, Hilton Worldwide, Howard Hughes Holdings, Restaurant Brands, Seaport Entertainment, and Uber.