Bill Ackman’s Pershing Square is facing a shareholder lawsuit challenging a deal it struck last year with real estate company Howard Hughes Holdings Inc. aimed at eventually creating a business ...

Is it really insider trading if you’re trading on yourself? A thorny question for prediction markets, spurred in part by a proposal from Bill Ackman.

Bill Ackman has endured a humbling three years: big public losses, an exodus by investors, and what a CEO calls an “ass-whooping” in an activist campaign. Now, the hedge fund titan could be making a ...