ADM is Exhibit A in the rise of a new type of corporate headquarters, one that arrives from afar but packs light. These headquarters represent the pinnacle of the corporate pyramid, snapped off and relocated, free of jobs tied to operations and often midlevel HQ functions such as payroll, human resources or purchasing. To be sure, migrating headquarters offer benefits to the city: They boost demand for business services, their executives join the philanthropic scene and, of course, they confer bragging rights. But in terms of jobs, the farther a company travels to set up shop in Chicago, the fewer people come with it.

"The notion of the corporate headquarters in the 'Mad Men' world when there were hundreds or thousands of people in a building with the company logo . . . those days are gone," says David Collis, a professor at Harvard Business School who studies corporate headquarters.

Chicago may have won ConAgra's headquarters recently, for example, but there's balm to soothe troubled city boosters in Omaha, Neb., its current hometown: The Gateway to the West will keep 1,200 office jobs—500 more than here—plus 900 in factories. In 2011, GE Transportation moved its headquarters here from Erie, Pa., along with 50 of 5,500 jobs. (The number in Chicago since has climbed to 150, while Erie has shrunk to 4,750, with more cuts planned this spring.) In 2013, design and construction firm Clayco agreed to make its 288-employee Chicago office its headquarters. The company now employs 620 here, while in its old home of St. Louis, it's grown to 1,025 from 700. The latest to announce plans to alight in Chicago, GE Healthcare, will pluck just the executive leadership team of 200 or fewer from suburban London, where it employs about 1,000.