Billionaire investor Bill Ackman is postponing the highly scrutinized listing of Pershing Square's U.S. closed-end fund, according to a notice on the New York Stock Exchange's website. The initial public offering of Pershing Square USA Ltd., with the ticker PSUS, has been delayed until a date to be announced, according to the website. Ackman is now looking to raise $2.5 billion to $4 billion for the fund, well short of the $25 billion target from a few weeks ago, according to a regulatory filing dated Thursday. Pershing Square declined to comment further. The firm issued a statement "to clarify press...