Qatar’s sovereign wealth fund, which plans to invest $35 billion in the U.S. in the next five years, is backing a commercial real estate investment trust run by a subsidiary of Leon Black’s Apollo Global Management LLC. The sovereign wealth fund led a group of investors that agreed in January to buy London’s Canary Wharf financial district in a transaction that valued the owner, Songbird Estates Plc, at about 2.6 billion pounds.