Index edges up 0.5% as 27 stocks rise

New Zealand shares rose, led by Metro Performance Glass, Tower and Trade Me Group, with little corporate news to drive prices ahead of earnings season.

The S&P/NZX 50 Index rose 33.07 points, or 0.5 per cent, to 7105.96. Within the index, 27 stocks rose, 15 fell and nine were unchanged.

Turnover was $139.5 million.

The day was positive despite school holidays and a lack of local news, said Craig Stent, a director at Harbour Asset Management.

The consumer price index, which rose less than expected in the June quarter and saw the dollar fall in response, was the key news of the day, Stent said.

Movements in the kiwi "do affect the way some of the dual-listed securities are priced - because they're listed in Australia, it tends to be the driver of some of the share prices, particularly the larger caps, because it's cheaper for Australian investors as they get priced higher in New Zealand".

Metro Performance Glass led the index, up 2.7 per cent to $1.89, a two-month high.

Tower rose 2.6 per cent to $1.385. It hit a three-week low of $1.315 on Thursday but has rebounded.

"There are a couple of large holders trying to sell that stock - Devon Funds Management filed down ... below 5 per cent, so that's probably why they've been under a bit of pressure," Stent said. "Maybe they've stopped selling ... and that's why they've bounced back up."

Trade Me gained 2.4 per cent to $5.07, a price not seen since May 2013, while Spark New Zealand advanced 2.2 per cent to $3.73.

Steel & Tube Holdings gained 1 per cent to $1.97.

Vector was the worst performer, falling 1.5 per cent to $3.36.

Argosy Property shed 1.3 per cent to $1.145, and Warehouse Group dipped 1.1 per cent to $2.78.

Outside the main index, Smartpay jumped 41 per cent to 22.5c, marking the biggest gain on the NZX's main board. Some 15,500 shares changed hands, less than a tenth of the 119,300 average daily volume over the past year.

SeaDragon gained 9.1 per cent to 1.2c. The fish oil refiner has hired Nevin Amos as its new chief executive. Amos will take over in October from interim chief executive Richard Alderton, who will remain on the board as a non-executive director.

Amos worked at Comvita, a cornerstone shareholder in SeaDragon, for nearly a decade.