About one in seven houses changing hands in Auckland are being bought by people who already own five or more properties.

New data shows people with multiple properties have been buying aggressively over the past four years.

Data from Core Logic shows the share of Auckland houses being bought by people with five or more properties has grown by 40 percent since 2012.

People in the category bought nearly 6000 out of 45,000 houses sold in the city last year.

The Auckland Property Investors' Association says it's surprised people with so many houses are still playing such a large role in the city's market.

President Andrew Bruce thinks prices have been pushed up by people who've heard others are making money in property.

"And then thinking 'wow, I should become a part of that as well', and we basically call these people the sort of 'FOMOs' or the 'Fear of Missing Out'."

Bruce said many of the big investors moved their interests outside the city after the Reserve Bank began clamping down on lending.

He said if he was a first home buyer, he'd be looking at buying an apartment.

"And I wouldn't necessarily be looking at brand new apartments or apartments off the plans, because generally when you're buying brand new apartments, you tend to be paying a premium for that apartment. It only makes sense because it's obviously expensive to build."