Slowing growth in house prices in Auckland is bringing down the national average.
The Real Estate Institute's national median price rose a seasonally adjusted 0.1 percent in May, compared to April, to $540,000.
Though prices nationally were a seasonally adjusted 6.2 percent higher than a year earlier, Auckland's growth was just 4.4 percent.
The institute's new measure, the House Price Index, showed the national activity fell in May by 0.4 percent from the month before. A 0.7 percent decline in Auckland's house market activity offset a 0.2 percent gain elsewhere.
REINZ chief executive Bindi Norwell said house price growth was still strong in the regions.
"May housing activity clearly shows continued buoyant activity across a number of regions which contrasts with the continuing stability of the Auckland region," she said.
"We saw record median prices achieved in four of the 14 regions we measure," she said, noting that prices rose in Northland, Manawatu/Wanganui, Nelson/Marlborough and Southland.
The national sales volume was down on the year earlier by a seasonally adjusted 22.2 percent, led by Auckland at 31.2 percent.
The decline was 17.4 percent if Auckland is excluded.
The median days to sell nationally increased by five to 37 days, compared to 32 days in May 2016.
Hawke's Bay had the shortest median days to sell at 30 days followed by Wellington and Nelson/Marlborough at 31 days. Westland had the longest median days to sell at 196 days, followed by Taranaki at 42 days, while in Auckland the median days to sell was 40 days - eight days longer than in the previous May.
Million-dollar home sales dropped over the past year.
The number of homes selling for more than $1M went down from 1240 to 1066 sales, or 14.5 percent of all properties sold, in the year to May.
But the number of properties going for less than $500,000 also declined - by 1,103 - in the same period.