Bonus, Severance: Carl Icahn, Bill Ackman Why activist investor Carl Icahn is up, and rival hedge fund manager Bill Ackman is down. Related Articles For Members Only Icahn’s Hedge Fund Stumbles Again as Shorts Backfire Stephen Taub Bill Ackman’s Pershing Square Is Losing Money, but He’s Still Asking Investors for More Michelle Celarier Press Release: Institutional Investor enters next chapter of growth with Apax Partners Sponsored by Apax