American hedge-fund manager. Ackman runs Pershing Square, whose London-listed Pershing Square Holdings has generated annualised investor returns of 16.2% after fees from its predecessor's debut in 2004 through the end of 2025—compared with 10.7% for the S&P 500. On April 29th 2026 he raised $5bn for Pershing Square USA, the largest "closed-end" fund ever launched, listed on the New York Stock Exchange. He calls it an attempt to build a modern-day Berkshire Hathaway.
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