Electricity providers "have had a very good week with the exception of today when they gave back those weekly gains", Williamson said.
"Obviously the hydro lakes and rain could be playing a part. There was talk they were getting pretty low and the producers probably benefiting, but a bit of rain could turn that around. There was a bit of profit taking in those stocks today."
Contact Energy led the index lower, down 1.9 per cent to $5.19. It had gained 3.5 per cent from $5.11 in the week up to today. Trustpower dropped 1.5 per cent to $5.40, and Genesis Energy was unchanged at $2.48.
Vector gained 0.3 per cent to $3.27. The company beat rivals to supply Australia's Territory Generation with battery storage technology in a multimillion-dollar deal for the New Zealand firm. Although Vector has smart meters in Australia, the Territory Generation contract is its first battery storage foray across the Tasman.
CBL Corp was the best performer, gaining 2.4 per cent to $3.39, and Infratil advanced 1.7 per cent to $2.98, with Kathmandu Holdings rising 1.5 per cent to $2.
Restaurant Brands rose 0.3 per cent to $5.98. The fast-food retailer is forecasting sales above $700m in the 2018 financial year as it reaps gains from its expansion into Australia and Hawaii.
Chief executive Russel Creedy said the company is now "a truly international one", leading to its management reorganisation into three geographic reporting divisions.