The number of Greater Des Moines residential properties that are valued at less than their mortgages dropped to 8,619 or 7.2 percent through the third quarter of 2014, according to real estate research firm CoreLogic Inc. The number of properties with negative equity was down from 8,913 properties in the second quarter of 2014. An additional 3.3 percent, or 3,911 residential properties, were in near negative equity for third quarter of 2014 compared with 3.6 percent, or 4,202, in second quarter.