The average investor can find compelling investment ideas by looking at what the big boys are doing. Regulations require larger asset managers to disclose their holdings every quarter, which can provide valuable insights into potential stocks to buy.

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.

Ackman aggressively bought more shares of a successful global investment company in Q3. He also upped his bet significantly on a turnaround play that's a household name. One of these stocks should be a good pick for growth investors, but not income investors.