"The market is continuing to punish Air New Zealand. It's pretty cautious about what increased competition will do to that company," Williamson said.
A2 Milk Co shed 4.2 per cent to $2.28, while Meridian Energy declined 2.9 per cent to $2.66.
Xero fell 1.7 per cent to $15.42. The cloud-based accounting software firm said it has sufficient cash reserves to reach breakeven without having to raise more capital, after posting a 67 per cent jump in full-year operating revenue and a wider net loss. Its net loss was $82.5 million in the 12 months ended March 31, from a loss of $69.5 million a year earlier.
Nuplex Industries rose 0.8 per cent to $5.33. The company, whose independent directors are backing a $1.05 billion takeover offer from Allnex Belgium, which values Nuplex at $5.55 a share, raised its 2016 earnings guidance, reflecting a stronger performance in the EMEA (Europe, the Middle East and Africa) and the Americas in March and April.
It said operating earnings before interest, tax, depreciation and amortisation for the year to June 30 would be in a range of $157 million and $161 million, up from its previous guidance of $145 million to $157 million.
"Although it has that scheme of arrangement, today's earnings announcement has seen the share price close the gap, but it might be all a little bit too late," Williamson said.
Restaurant Brands New Zealand was the biggest gainer, up 2.3 per cent to $5.45. NZX rose 2 per cent to $1.01 while Summerset Group Holdings rose 1.6 per cent to $4.46.
Sky Network Television halted its slide, rising 1.5 per cent to $4.12. The stock dropped 26 per cent over four sessions of losses since last Friday after saying subscriber numbers were expected to fall further this financial year, causing earnings next year to miss analyst estimates.
"It has been savaged this week, but hasn't fallen any further," Williamson said. "Investors will be pretty cautious, a number of analysts are saying they need to change their models for that stock."
Outside the main index, Delegat Group was unchanged at $5.99. The winemaker that retails under brands including Oyster Bay says it has completed the 2016 harvest, with yields in New Zealand up 33 per cent on a difficult 2015. It says it will have appropriate inventory to achieve planned future sales growth of 3.17 million cases by 2020.
Energy Mad was unchanged at 6.5c. The energy-efficient light-bulb marketer will outsource its NZ direct-to-consumer sales in a bid to focus on its growing Australian market.
The company says this is expected to increase the operating profit from direct-to-consumer sales in NZ.
That area of business recorded an unaudited operating loss of $127,000 on $542,000 of sales between February and April, before depreciation and amortisation of $5000.
The shares have gained 62 per cent since the start of the year but remain well below the $1 float price when the company joined the NZX in September 2011.