Almost two of every five owners of single-family, detached homes in the Chicago area were underwater on their mortgage in December, an all-time high and far outpacing national trends, according to data to be released by Zillow.com Wednesday.

The realty Web site found that 38.6 percent of all single-family detached homes with a mortgage had negative equity, meaning homeowners owed more on the homes than the properties were worth in the fourth quarter, compared with 32.9 percent in the third and 28.3 percent a year earlier. Nationally, the negative equity rate was 27 percent in the fourth quarter, up from 23.2 percent in the third quarter. Get the full story »