Who Is Bill Ackman?

Meet the hedge fund manager who's worth $9.3 billion.

By Kristi Waterworth – Updated Sep 17, 2025 at 9:25 PM | Fact-checked by Frank Bass

Key Points

Bill Ackman invests in undervalued companies to boost their management and stock value.
His successful bet against MBIA in 2009 earned him $1.4 billion.
Ackman's strategy includes large stakes in major companies for substantial influence.

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.

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Executives in a conference room for a board of directors meeting. — Image source: Getty Images.

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Investing is a business where you can look very silly for a long period of time before you are proven right.
Bill Ackman

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About the Author

Kristi Waterworth has been a contributing real estate and financial expert at The Motley Fool, covering real estate, investing, and personal finance topics, since 2020. Kristi has been interviewed by various TV media outlets and podcasts for her real estate investing expertise – from residential real estate to digital real estate and everything in between. Kristi’s journalist career spans over 25 years, and she has written about real estate investing, homeownership, and home construction specifically for the last decade. She was also previously a licensed Realtor and general building contractor before the Great Recession and housing market collapse. She holds a bachelor’s degree in American history from Columbia College in Missouri.

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Kristi Waterworth has no position in any of the stocks mentioned. The Motley Fool has positions in and recommends Canadian Pacific Kansas City. The Motley Fool has a disclosure policy.