Bill Ackman founded Pershing Square Capital Management in 2004 and built it into one of the best-known activist hedge funds, taking large, concentrated stakes in a handful of companies and publicly pressing for changes. His holdings have included Amazon, Alphabet, Chipotle, and Uber, and his fund oversees roughly $15 to $20 billion.
Beyond markets, Ackman has used a very large following on the social platform X to wade into public life, most prominently in a 2023-2024 campaign accusing elite universities of tolerating antisemitism that contributed to the resignation of Harvard President Claudine Gay. A longtime Democratic donor, he endorsed Donald Trump in the 2024 election.
Pershing Square owns roughly 10 percent of the common stock of mortgage giants Fannie Mae and Freddie Mac, positioning Ackman to benefit from any move to take them out of government conservatorship, an example of how his financial and political activity can intersect.
What they control
- Pershing Square Capital Management: an activist hedge fund with concentrated stakes, roughly $15 to $20 billion in assets
- Pershing Square Holdings: a publicly listed closed-end investment vehicle
- Howard Hughes Holdings: chairman of the real-estate development company
- Roughly 10 percent of the common stock of Fannie Mae and Freddie Mac
- A very large personal platform on X used to move markets and shape public debate
Key institutions & holdings
Activist hedge fund known for concentrated, high-conviction positions.
Master-planned-community and real-estate developer in which Ackman is the largest holder.
Pershing Square stands to gain from any privatization of the mortgage giants.
Key facts
- Founded Pershing Square Capital Management in 2004.
- Net worth estimated around $8 to $9 billion in 2026.
- Led a 2023-2024 campaign over campus antisemitism that contributed to Harvard President Claudine Gay's January 2024 resignation.
- Endorsed Donald Trump in the 2024 election after years of donating to Democrats.
- Pershing Square owns roughly 10 percent of the common stock of Fannie Mae and Freddie Mac.
- Withdrew the planned Pershing Square USA closed-end fund IPO in 2024 after weak investor demand.
Timeline
- 2004Founds Pershing Square Capital Management.
- 2023-12Launches a public campaign against Harvard over campus antisemitism.
- 2024-01Harvard President Claudine Gay resigns; Ackman announces an anti-antisemitism organization.
- 2024Endorses Donald Trump and withdraws the Pershing Square USA IPO.
- 2025-2026Promotes the privatization of Fannie Mae and Freddie Mac, in which he holds stakes.
Controversies
Pressure campaign against Harvard · 2023-2024
Ackman's high-profile push to oust Harvard's president and reshape university governance, amplified through his large X following, drew both praise and criticism that a billionaire was using leverage as a donor and public figure to bend an institution.
Herbalife short bet · 2012-2018
Ackman waged a years-long public campaign betting against Herbalife as an alleged pyramid scheme, ultimately exiting at a large loss after a bitter feud with rival investor Carl Icahn.
Fannie and Freddie advocacy · 2025-2026
Ackman publicly champions ending the conservatorship of Fannie Mae and Freddie Mac while holding roughly 10 percent of their common stock, a position critics flag as a conflict of interest.
Network
- Neri OxmanSpouseDesigner and former MIT professor; became the subject of a counter-controversy over plagiarism allegations in 2024.
- Carl IcahnRivalClashed publicly with Ackman during the Herbalife battle.
- Donald TrumpEndorsed candidateAckman backed Trump in the 2024 election.
Why this matters
Ackman shows how a single investor can convert financial success into political and institutional power: moving share prices with a post, pressing universities to remove leaders, backing a presidential candidate, and lobbying for policies, such as privatizing the mortgage giants, in which he holds a direct financial stake. That blurs the line between private wealth and public decision-making.