Bill Ackman's Pershing Square USA has withdrawn plans for an initial public offering (IPO). What Happened: Investor demand appeared to wane from initial expectations. Ackman acknowledged that a key concern was whether investors would be better off waiting to invest in the aftermarket rather than during the IPO. This led to a decision to reevaluate the IPO’s structure, with plans to return with a revised proposal according to CNBC. "While we have received enormous investor interest in PSUS, one principal question has remained: Would investors be better served waiting ...