Real estate agents Barfoot & Thompson sold 889 properties in May - a 25% increase over April and 12% up on a year earlier.
The agency has a 40% share of the Auckland market.
Managing director Peter Thompson says there appears to be much more confidence in the market and low interest rates are having an effect.
But he says the major issue is a lack of choice for buyers, with the agency's listings at a 20-month low.
Prices in May reversed a three-month trend of rising values. The May average of $529, 284 was down 2.8% on April, the agency said.