The Pershing Square Capital Management founder also revealed his fund bought a 6% stake in Domino's Pizza. : Billionaire investor Bill Ackman warned inflation may not be temporary and said the Federal Reserve may have to raise interest rates in a Wednesday interview at the Wall Street Journal Future of Everything Festival. The Pershing Square Capital Management founder also revealed that his fund recently purchased a 6% stake in Domino's Pizza, sending the shares up as high as 5.9% Wednesday. 1. "We've admired it for years, and it was just never cheap enough.