Construction firm's stock rises on speculation about housing boom but Auckland Airport falls amid heavy trading.

New Zealand shares gained as Fletcher Building reached its highest level this year on speculation it will benefit from housing demand, while Auckland International Airport, which fell, was the most heavily traded stock. Orion Health Group, Sky Network Television and Air New Zealand all rose.

The S&P/NZX50 Index rose 19.78 points, or 0.3 per cent, to 7039.42. Within the index, 27 stocks advanced, 16 declined and seven were unchanged. Turnover was $473.1 million.

Fletcher Building rose 1.5 per cent to $8.95, and is up 20 per cent for the year.

"All the talk about a housing shortage is pretty good news for a stock like Fletcher Building and investors, particularly Australian investors, are pretty keen on the stock at the moment," said Grant Williamson, director at Hamilton Hindin Green.


"They view Fletcher Building as undervalued compared to the peers in Australia."

Orion Health Group was the biggest gainer, up 6 per cent to $5.15. It has gained 52 per cent this year and last week announced it was targeting a return to profit in 2018 after reporting a 26 per cent increase in annual revenue and a narrowed loss.

Auckland International Airport dropped 2.6 per cent to $6.24. The listed airport was the most traded stock on the index, with 25.8 million shares equating to 2.3 per cent of all its shares available, or $161.1 million dollars, through yesterday.

Kathmandu Holdings rose 3.9 per cent to $1.59, A2 Milk Co gained 3.3 per cent to $1.58, and Summerset Group advanced 3.2 per cent to $4.80.

Sky Network Television gained 2 per cent to $4.50. It's risen 13 per cent in the past fortnight after the stock plummeted when the pay-TV operator said subscriber numbers were expected to fall further this financial year, causing earnings next year to miss analyst estimates.

"It's been sold down over the past few weeks - news on the loss of subscribers really dented investor confidence so it got hit very hard, but it is certainly showing some good signs of recovery at the moment," Williamson said.

Air New Zealand advanced 1.6 per cent to $2.25. Yesterday, Chinese airline operator HNA Aviation Group announced it had bought a 13 per cent stake in Virgin Australia. Air New Zealand is considering selling its 25.99 per cent stake in Virgin.

Kiwi Property Group shed 4.2 per cent to $1.485 after giving up rights to a 3.3c dividend.

Freightways dropped 3.2 per cent to $6.60, Mighty River Power fell 1.7 per cent to $2.97 and Comvita declined 1.6 per cent to $12.55.

Outside the main index, TruScreen gained 10 per cent to 27.5c. The NZAX-listed cervical cancer test developer will have its technology used in a major cervical cancer screening programme in north-eastern China. The company will stay on the NZAX platform for the next 12 months having been told it won't need to migrate to the NXT platform.

Wynyard Group gained 2.8 per cent to 73c. The Auckland-based intelligence software developer has continued its boardroom refresh with two new appointments including New Zealand Venture Investment Fund chief Richard Dellabarca as deputy chair and former NZME executive Phil Eustace as interim chief financial officer.

VMob Group gained 5.7 per cent to 37c. Australian and New Zealand high net worth investors and institutions have stumped up $3.3 million to help the mobile marketing platform company pursue offshore expansion, particularly in the US.