(Reuters) -Billionaire investor Bill Ackman's Pershing Square Capital Management will buy 9 million newly issued shares of real estate developer Howard Hughes Holdings for $900 million, the companies said on Monday.

The deal involves Pershing Square buying 9 million newly issued shares of Howard Hughes for a total cost of $900 million. The purchase price is 48% above where the stock closed Friday, and puts Pershing's stake in the company at 46.

Ackman, Pershing Square’s chairman and CEO, would become executive chairman of the Howard Hughes board. Hughes CEO David O’Reilly would retain his role.