"We've seen a lot of uneasiness overnight in regard to Theresa May - she got the vote of confidence, if you can say that," said Peter McIntyre, an investment adviser at Craigs Investment Partners.
"Trade tensions eased and it's given the market some relief and there's been a sea of green across Asia today."
Fletcher Building led the market higher, up 4.5 per cent to $4.91, a three-week high, on slightly busier volumes than usual of 1.7 million. A notice to the NZX yesterday showed Australian fund manager Perpetual increased its stake in the building company to 11 per cent. The stock is also coming off a 14-year low in November, and an announcement on the sale of the Formica international business is expected in coming weeks.
Air New Zealand rose 1.3 per cent to $3.02 after reaching an agreement with workers who threatened to strike in the run-up to Christmas. The industrial action would have affected 120,000 travellers. Auckland International Airport rose 1.7 percent to $7.10.
Spark New Zealand was the most active stock on a volume of 3.4 million, slightly busier than usual. It fell 0.5 per cent to $4.31.
Trade Me slipped 0.6 per cent to $6.33 on a volume of 2.3 million shares. The online marketplace said a potential suitor dropped out of a bidding war after it put UK private equity firm Apax Partners in the box seat yesterday, agreeing to a planned scheme of arrangement at $6.45 a share.
McIntyre said the lower threshold for Apax to takeover Trade Me means it looks likely it will delist from the local stock market. NZX was unchanged at $1.
Restaurant Brands slipped 0.2 per cent to $8.45 on 1.2 million shares, more than four times its average volume. The fast-food retailer is under a partial takeover offer by Mexico's Finaccess Capital. Third-quarter sales released today were slightly below expectations, McIntrye said.
Meridian Energy rose 1.5 per cent on heavier trading of 1.9 million. Chair Chris Moller announced he will retire from the board at next year's annual meeting and be replaced by recent board recruit Mark Verbiest.
Of other companies with volumes of one million shares or more, Sky Network Television was unchanged at $2.06, A2 Milk rose 2.2 per cent to $11.13 and Infratil gained 2 per cent to $3.62.
Contact Energy fell 2 per cent to $5.80 in light trading, posting the biggest decline on the NZX 50.
Outside the benchmark index, the tightly held TIL Logistics was unchanged at $1.50. Its Pacific Fuel Haul subsidiary reached an agreement with tanker drivers who threatened strike action, which could have disrupted the country's petrol supply. Fuels retailer Z Energy rose 0.5 per cent to $5.73.
Vital Healthcare Property Trust was unchanged at $2.05. The New Zealand Shareholders' Association threw its weight behind dissident investors seeking to change the governance of the property trust, saying the manager has treated unitholders with contempt.