Hey, you looking for a place on Manhattan's Upper West Side?Well, if you've got $20 million, Bill Ackman might be able to help you.Related: Billionaire Bill Ackman buys 3 million shares of battered consumer stockThe billionaire hedge fund manager has listed two neighboring apartments for a total of $19.

Over the last two quarters, Ackman has built two new significant positions for Pershing Square -- Nike (NYSE: NKE) and Brookfield (NYSE: BN) -- piling an estimated $2.2 billion into those stocks during the third quarter alone. Here's why.

Pershing Square bought roughly 25.9 million shares of Brookfield in Q3, increasing its stake by almost 378%. Brookfield is a dividend stock, but I doubt there's an income investor on the planet who would get excited about the company's dividend.

Unsurprisingly, billionaire investor Bill Ackman added to his position in footwear giant Nike (NYSE:NKE) during the last quarter. As to whether Ackman is finished building his position remains the multi-billion-dollar question.