Getty Images Real estate is an important component of the U.S. and global economies. For many Americans, homeownership doubles as a first investment. Beyond a primary residence, investors also can buy into the commercial real-estate market: Office buildings, multifamily housing, hospitals, parking lots, storage facilities, retail properties, call centers, distribution hubs, hotels and restaurants form a sector with its own economic ups and downs. In 2016, the S&P 500 recognized real estate as...