Billionaire activist investor Bill Ackman’s Pershing Square Capital Management has confidentially filed in the U.S. for an initial public offering of a blank check company, according to a person familiar with the matter.

Pershing Square could aim to raise more than US$1 billion for the investment vehicle, the person said, asking not to be identified as the details aren’t public. Reuters earlier reported the IPO plans.

Blank check companies -- also known as special purpose acquisition companies -- raise money on the public markets to make an acquisition within a set period of time. A target isn’t identified until after the shares are trading.