Nassef Sawiris's family office revealed a 5% stake in the company that owns two New York sports teams.
The company is aiming to go public as soon as the first quarter of 2021, sources said.
Ackman has repeatedly called for a complete shutdown of the U.S. for 30-days.
Billionaire Nelson Peltz stands to make about $266 million over the past decade on Legg Mason, which is being acquired.
Employees of his who don’t make the move won’t have a job, a source said.
The fund has returned 54.5% on its investments this year through August.
Ackman's Pershing Square is getting a taste of its own medicine from activist investors.
The downturn will lead to a market correction of up to 40 percent, he said.
The fund plans to invest in six projects in designated opportunity zones, including areas in Brooklyn and the Bronx.
On Wednesday, Brookfield Asset Management agreed to buy a majority stake in Oaktree Capital.