Shares in the three Government-controlled power companies have taken a hit, after a Roy Morgan poll indicated a Labour-Green government would win if an election was held today.
The NZX 50 fell 27 points, closing at 5,161, on Thursday.
Shares in Meridian Energy fell more than 3 percent, Mighty River Power was down 1.7 percent, and Genesis Energy was down more than 1 percent.
A director at the sharebroker Hamilton Hindin Greene, Grant Williamson, said the poll unsettled some investors.
"The last few weeks, ever since Genesis came on the market, they've been firming up very nicely but all of them have come under a little bit of selling pressure today and I think that would be in reaction to the Government maybe struggling a little bit in election polls."
Mr Williamson, said shares in Ryman Healthcare hit an all-time high in Thursday trading of $9.05, ahead of the company's results.
But it closed down a little weaker at $8.80, after investors took the opportunity to make a profit.
In other trading, shares in The Warehouse Group are flat at $3.38 after the retailer reported an 8 percent rise in third quarter sales to $604 million.
And shares in Z Energy are down 1.2 percent to $3.83 after its full-year profit fell by nearly a third.
In other business news, the Bank of New Zealand's first half net profit has jumped by almost a third largely due to improved revenue and charges against profit for bad loans.
On the currency markets, better than expected Australian unemployment data caused the New Zealand dollar to fall against the Australian currency.
The currency strategist at Westpac, Imre Speizer, said the Kiwi fell about half a cent against the Aussie dollar following the news that unemployment across the Tasman remained unchanged at 5.8 percent.
He said that was followed by some China balance data, that was also "quite decent", and that helped the Aussie as well. The Kiwi-Aussie cross rates fell from 92.80 to 92.30, he said.
Shortly after 5pm, the Kiwi was buying 86.60 US cents, 92.40 Australian cents, 51.07 British pence, 0.6223 euro, 88.18 yen and 5.39 renminbi.