Mostly in the lowest third of valuation.
From the Bloomberg story, here:
"A decade after U.S. home sales peaked, 15.4 percent of owners in the first quarter owed more on their mortgages than their properties were worth, according to a report Friday by Zillow Inc. While that’s down from a high of 31.4 percent in 2012, it’s still alarmingly above the 1 or 2 percent that marks a healthy market, said [Stan] Humphries, the chief economist at the Seattle-based real-estate data provider. Worse yet: The pace of healing is losing steam. ... While 25.5 percent of homes valued in the lowest third are underwater, just 14.1 percent of those in the middle have negative equity. For the top group, the figure is even lower -- 8.3 percent."
