At the end of the first quarter of 2009, 23.4 percent of all homeowners in the Chicago area were “under water,” with mortgages that exceeded their home’s present value, according to a May study by Zillow.com, the real-estate website. Among the ten largest U.S. metro areas, Chicago-Naperville-Joliet had the fourth-highest rate of negative equity, behind Miami (29.3 percent), San Francisco (27.1 percent), and Washington, D.C. (23.9 percent). The nationwide figure is 21.9 percent. Stan Humphries, Zillow’s vice president of data and analytics, says that because Chicago’s prices never spurted as high as those in other cities, there was less “padding” in home values here when the big drop hit.