Just over 13 percent of all properties sold in the second quarter of this year changed hands for less than the seller paid for them, and the number tops 20 percent in Auckland.

Cotality has released its latest "pain and gain" report, which tracks how many sellers are taking a loss. It will understate the true number because it does not include the costs of sale, such as real estate agent commissions.

Across the country 13.1 percent of properties sold in the second quarter were at a loss, the highest number since 2012. In Auckland, the proportion was 20.9 percent and in Wellington it was 18.4 percent.

Why have Ooshies taken over my house?

The median amount lost was $60,000, for a total loss of $159 million. The median gross profit was $280,000, down from $440,000 at the peak.

People who made money on their properties had held them for a record length of time - 10.4 years. People who sold had only held for a median 4.3 years.

Cotality chief economist Kelvin Davidson said that could indicate that people were choosing to hold for longer than previously to wait for a market recovery or because selling was more difficult than usual.

Apartments were much more likely to be sold for a loss, at 45.4 percent.

It was the weakest resale performance for apartments since 2010.

Davidson said apartments had fallen in value by 6 percent on average in the past 12 months compared to 2 percent for townhouses and little movement for standalone swellings.

He said apartments tend to be more likely to resell at a loss because they did not have as much capital growth over time, even in an upswing. "They're a bit more vulnerable to being sold at a loss simply because they haven't made as much capital gain through the cycle so that's part of it."

Some parts of the country had very small percentages selling for a loss such as Timaru and Gore, where 1.8 percent of sales lost money.

Davidson said the pattern was consistent with lower house prices.

"It's been a pretty sluggish housing market for a number of years so no surprise that resellers are not faring as well as they have done in the past. The 13 percent of resales in the second quarter sold for a loss is the highest figure we've seen for 11 or 12 years but it's been more of a slow grind downwards, it hasn't been the sharp adjustment we saw in the global financial crisis.

"Back then, the share of properties being sold for a loss rose from nothing to about 20 percent in a year or two. This time it's risen from nothing to around 13 percent in four or five years so it's been an adjustment but it's been a bit slower than what we've seen in the past. It's consistent with the servicing testing that we've got within the banks now.

"People who might have run into problems and had to sell sooner than what they thought, perhaps haven't even got the mortgage in the first place. And also employment has stayed up, people have stayed in work. So that's helped sellers in terms of they can hold on a little bit longer if they need to. They don't necessarily have to sell at a loss."

He said the four-year median hold period for losses went back to the start of the housing market slowdown.

"We've seen regionally Auckland's still a little bit weaker, Wellington's a little bit weaker. There's perhaps no great surprises there."

He said he did not expect things to turn around any time soon.

"We've still got economic uncertainty. If anything, mortgage rates are sneaking higher. There are still a lot of listings out there. It's a buyer's market. So I just think house prices might not necessarily fall too much further because affordability has been restored quite a lot, but they may not necessarily rise any time soon either. And with that pricing power probably resting with buyers, it's going to be just a little bit challenging for sellers or property resellers for the next little while."